Ropivacaine-Clonidine-Ketorolc (ropivacaine HCl/clonidine HCl/ketorolac tromethamine)

Dosage of ropivacaine hydrochloride is expressed in terms of ropivacaine hydrochloride. Dosage of ropivacaine hydrochloride varies with the anesthetic procedure, degree of anesthesia required, surgical site, and individual patient response. The smallest dose and lowest concentration required to produce the desired effect should be used. Rapid administration of a large single dose should be avoided. The manufacturer's dosage recommendations are based on the expected average dosage range necessary to produce a successful block in adults and should be used as a general guideline.

Regardless of the route of administration, to avoid the possibility of precipitating the withdrawal syndrome, clonidine therapy should not be discontinued abruptly.

Dosage of clonidine is expressed in terms of clonidine and clonidine hydrochloride.

The lowest possible effective dosage and shortest duration of therapy consistent with treatment goals of the patient should be employed.

Current principles of pain management indicate that analgesics, including ketorolac tromethamine, preferably should be administered at regularly scheduled intervals, although the drug also has been administered on an as-needed basis (i.e., withholding subsequent doses until pain returns). The manufacturer states that clinicians should manage breakthrough pain in adults receiving ketorolac tromethamine therapy with supplemental low doses of opiate analgesics (unless contraindicated) as needed rather than considering higher or more frequent dosages of ketorolac tromethamine.

Because there is some evidence of dose-related adverse effects (e.g., GI bleeding), particularly in geriatric patients, the lowest possible effective ketorolac tromethamine dosage should be employed, and total duration of therapy with the drug (including parenteral, oral, and intranasal formulations) should not exceed 5 days. Particular caution and reduced dosage should be employed in geriatric patients, adults weighing less than 50 kg, and those with renal impairment (see Dosage in Renal and Hepatic Impairment under Dosage and Administration). Elimination of the drug generally is slower and sensitivity to adverse renal effects of NSAIAs generally is increased in geriatric patients.

Ropivacaine hydrochloride may be administered by epidural block, peripheral nerve block (e.g., brachial plexus block), or local infiltration. The manufacturer states that ropivacaine should not be used for obstetrical paracervical block, retrobulbar block, or spinal anesthesia (subarachnoid block), and should not be administered using the Bier block technique (IV regional anesthesia).

Local anesthetics, including ropivacaine, have been administered by continuous intra-articular infusion+ (e.g., for control of postoperative pain); however, such use has been associated with chondrolysis. (See Cautions: Musculoskeletal Effects in the Local Anesthetics, Parenteral, General Statement 72:00.)

To prevent intravascular or subarachnoid injection of a large epidural dose of ropivacaine hydrochloride, a test dose (e.g., 3-5 mL of a short-acting local anesthetic solution containing epinephrine) should be injected prior to administering the total dose. When clinical conditions permit, use of a test dose solution that contains epinephrine should be considered to detect inadvertent intravascular injection. The test dose should be repeated if the epidural catheter is displaced. An adequate time for onset of anesthesia should be allowed following administration of each test dose.

Clonidine hydrochloride is administered orally or by epidural infusion; clonidine is administered orally or percutaneously by topical application of a transdermal system.

The potential benefits and risks of ketorolac therapy as well as alternative therapies should be considered prior to initiating ketorolac therapy.

Ketorolac tromethamine is administered by IM or IV injection, orally, or intranasally.

No dosing information is available for this tab.

No dosing information is available for this tab.

No formal drug interaction studies have been performed to date with ropivacaine hydrochloride.

Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

Agents Affecting Growth Hormone/Macimorelin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Agents affecting growth hormone may impact the accuracy of the macimorelin diagnostic test.(1)

CLINICAL EFFECTS: Concurrent use of agents affecting growth hormone may impact the accuracy of the macimorelin diagnostic test.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of macimorelin states concurrent use with agents affecting growth hormone may impact the accuracy of the macimorelin diagnostic test. Discontinue growth hormone products at least 1 week before administering the macimorelin diagnostic test. Sufficient washout time of drugs affecting growth hormone release prior to administration of macimorelin is recommended.(1) Agents affecting growth hormone include: - Drugs that directly affect the pituitary secretion of growth hormone (e.g. somatostatin, insulin, glucocorticoids, cyclooxygenase inhibitors) - Drugs that may transiently elevate growth hormone concentrations (e.g. clonidine, levodopa, insulin) - Drugs that may blunt the growth hormone response (e.g. muscarinic antagonists, anti-thyroid medications, growth hormone products)

DISCUSSION: Concurrent use of agents affecting growth hormone may impact the accuracy of the macimorelin diagnostic test.(1)

Ketorolac (Injectable)/Nsaid;Aspirin (Injectable)

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Possible additive or synergistic side effects.(1)

CLINICAL EFFECTS: Concurrent use of multiple dose of ketorolac with other non-steroidal anti-inflammatory agents (NSAIDs) or aspirin may result in an increase in NSAID-related side effects.(1)

PREDISPOSING FACTORS: Patients with pre-existing renal impairment may be at an increased risk of adverse effects from this interaction. The risk for bleeding episodes may be greater in patients with multiple disease-associated factors (e.g. thrombocytopenia, advanced liver disease). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g., anticoagulants, antiplatelets, corticosteroids, selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs). Risk of GI bleed may be increased in patients who are of older age, in poor health status, or who use alcohol or smoke. Risk may also be increased with longer duration of NSAID use and prior history of peptic ulcer disease and/or GI bleeding.

PATIENT MANAGEMENT: The manufacturer of ketorolac states that concurrent use of ketorolac with either other NSAIDs or aspirin is contraindicated.(1)

DISCUSSION: There is no clinical documentation to support this interaction. The manufacturer of ketorolac states that as a result of the cumulative risks of inducing serious NSAID-related adverse events, the concurrent administration of ketorolac with other NSAIDs or aspirin is contraindicated.(1)

Ketorolac (Injectable)/Nsaids; Aspirin (>300 Mg); Salicylate

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Possible additive or synergistic side effects.(1)

CLINICAL EFFECTS: Concurrent use of multiple doses of ketorolac with other non-steroidal anti-inflammatory agents (NSAIDs), salicylates or aspirin may result in an increase in NSAID-related side effects such as bleeding or renal impairment.(1-3)

PREDISPOSING FACTORS: Patients with pre-existing renal impairment may be at an increased risk of adverse effects from this interaction. The risk for bleeding episodes may be greater in patients with multiple disease-associated factors (e.g. thrombocytopenia, advanced liver disease). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g., anticoagulants, antiplatelets, corticosteroids, selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs). Risk of GI bleed may be increased in patients who are of older age, in poor health status, or who use alcohol or smoke. Risk may also be increased with longer duration of NSAID use and prior history of peptic ulcer disease and/or GI bleeding.

PATIENT MANAGEMENT: The manufacturer of ketorolac states that concurrent use of ketorolac with either other NSAIDs, salicylates or aspirin is contraindicated.(1) If concurrent therapy is deemed medically necessary, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: Manufacturers of ketorolac state that concurrent use of ketorolac with either other NSAIDs, salicylates or aspirin is contraindicated.(1,2) If concurrent therapy is deemed medically necessary, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Conduct periodic monitoring of renal function, especially in patients with renal impairment.

Ketorolac/Oat3 Inhibitors

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Inhibitors of organic anion transporter 3 (OAT3) may inhibit the renal clearance of ketorolac.

CLINICAL EFFECTS: Enhanced ketorolac toxicity including gastrointestinal and renal toxicity as well as increased risk of bleeding.

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Concomitant administration of ketorolac and organic anion transporter 3 (OAT3) inhibitors are contraindicated by the manufacturer. If concurrent therapy is deemed medically necessary, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: Probenecid has been reported to increase serum concentrations and toxicity of nonsteroidal anti-inflammatory drugs (e.g., indomethacin, ketoprofen, naproxen).(1-3) Based upon material from the manufacturer of ketorolac, concurrent administration of probenecid and ketorolac also increases serum concentrations of the NSAID ketorolac and produces a 2-fold increase in the half-life of ketorolac and a 3-fold increase in the area under the plasma concentration-time curve.(4) Ketorolac is a potent NSAID analgesic and increasing the serum concentrations may increase the risk of occurrence of serious renal, GI and hematologic side effects. OAT3 inhibitors linked to this monograph include: cabotegravir, leflunomide, nitisinone, probenecid, teriflunomide, and vadadustat.(5)

Ketorolac/Pentoxifylline

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Ketorolac affects platelet function.(1) Pentoxifylline affects blood viscosity.(2)

CLINICAL EFFECTS: Concurrent use of ketorolac and pentoxifylline may result in an increased risk of bleeding.(1-3)

PREDISPOSING FACTORS: Concomitant use of other medications known to increase risk of bleeds (anticoagulants, aspirin, other NSAIDs, probenecid, lithium).(1-3) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding.

PATIENT MANAGEMENT: The US manufacturers of ketorolac(1) and pentoxifylline(2) states that concurrent use of these agents is contraindicated. The Australian manufacturer of ketorolac recommends careful monitoring if ketorolac is administered concomitantly with other medications that affect hemostasis such as pentoxifylline.(3) If concurrent therapy is deemed medically necessary, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: When ketorolac is administered with pentoxifylline, there is an increased tendency to bleeding.(1)

Selected Nephrotoxic Agents/Bacitracin

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Bacitracin may cause renal failure due to glomerular and tubular necrosis. Concurrent administration of other nephrotoxic agents may result in additive renal toxicity.(1-3)

CLINICAL EFFECTS: Concurrent use of bacitracin with other potentially nephrotoxic agents may result in renal toxicity.(1-3)

PREDISPOSING FACTORS: Dehydration and high-dose bacitracin may predispose to adverse renal effects.(1)

PATIENT MANAGEMENT: Health Canada states that bacitracin is contraindicated in patients with renal impairment, including those taking other nephrotoxic drugs.(1) The Canadian and US manufacturers of bacitracin state that concomitant use of bacitracin with other potentially nephrotoxic agents should be avoided.(2,3)

DISCUSSION: Renal impairment is a major toxicity of bacitracin. Cases of nephrotoxicity have been reported when bacitracin was used off-label.(1-3)

Selected Nephrotoxic Agents/Cidofovir

SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient.

MECHANISM OF ACTION: Cidofovir is nephrotoxic. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1-3)

CLINICAL EFFECTS: Concurrent use of cidofovir with nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, foscarnet, intravenous pentamidine, tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1-3) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The Australian,(1) UK,(2) and US(3) manufacturers of cidofovir state that concurrent administration of potentially nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, foscarnet, intravenous pentamidine, tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1-3) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin. These agents should be discontinued at least 7 days before the administration of cidofovir.

DISCUSSION: The safety of cidofovir has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is the major toxicity of cidofovir.(1-3)

Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

Acetaminophen; Nsaids/Alprostadil

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Alprostadil is a prostaglandin E1 product used to maintain patency of a patent ductus arteriosus (PDA).(1) Acetaminophen and nonsteroidal anti-inflammatory (NSAID) agents inhibit prostaglandins and may be used for PDA closure in addition to pain/fever management.(2-4)

CLINICAL EFFECTS: Simultaneous administration of acetaminophen or NSAIDs may result in decreased clinical effects from alprostadil, including reduction in PDA.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Avoid concurrent administration of acetaminophen or NSAIDs in patients on alprostadil for maintaining patency of a patent ductus arteriosus (PDA).(1)

DISCUSSION: NSAIDs and acetaminophen are used as management for patent ductus arteriosus (PDA) closure.(2-4) Alprostadil is used to maintain patency of a PDA.(1) In a case report, a 37-week gestational age neonate with cardiac defects required alprostadil therapy for PDA patency. After multiple doses of acetaminophen for pain, an echocardiogram showed reduction of the PDA requiring increased doses of alprostadil. Additional acetaminophen was discontinued. Follow up echocardiogram showed successful reversal of PDA reduction and alprostadil dose was reduced.(5)

Agents That Cause Bradycardia/Crizotinib

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Crizotinib may cause symptomatic bradycardia. Additional agents that cause bradycardia further increase the risk for symptomatic bradycardia.(1)

CLINICAL EFFECTS: Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsade de pointes.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of crizotinib recommends avoiding concurrent use of crizotinib and other agents known to cause bradycardia to the extent possible. If combination therapy is required, monitor heart rate and blood pressure regularly. If bradycardia occurs, withhold crizotinib until heart rate recovers to 60 bpm or above, or patient is asymptomatic. Re-evaluate the use of the concomitant medication. If the concomitant medication is discontinued or its dose is reduced, resume crizotinib at the previous dose upon patient's recovery. If the concomitant medication is not discontinued or dose adjusted, resume crizotinib at a reduced dose upon patient's recovery. If life-threatening bradycardia occurs, discontinue or reduce the dose of the concomitant medication. Upon the patient's recovery, lower the dose of crizotinib to 250 mg daily. Monitor blood pressure and heart rate frequently.(1)

DISCUSSION: Across clinical trials, bradycardia occurred in 13 % of patients on crizotinib, and grade 3 syncope occurred in 2.4 % of patients on crizotinib compared with 0.6 % on chemotherapy.(1) Agents that may cause bradycardia and linked to this monograph include: beta-blockers, non-dihydropyridine calcium channel blockers, clonidine, digoxin, and moxonidine.(1)

Agents That Cause Bradycardia/Etrasimod

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Initiation of etrasimod has caused transient decreases in heart rate and atrioventricular conduction delays after the first dose. The first dose has also been associated with heart block. Additional agents that cause bradycardia further increase the risk for symptomatic bradycardia.(1)

CLINICAL EFFECTS: The heart rate lowering effect of etrasimod is transient and is usually seen with the first dose. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsade de pointes.(1)

PREDISPOSING FACTORS: Pre-existing cardiovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, history of torsades de pointes, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to etrasimod initiation, or factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia, bradycardia, female gender, or advanced age) may increase risk for cardiovascular toxicity due to etrasimod.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The prescribing information for etrasimod treatment states that advice from a cardiologist should be sought before initiating etrasimod treatment in patients currently taking additional agents that cause bradycardia or in patients with preexisting heart and cerebrovascular conditions, with resting heart rate of less than 50 bpm, history of symptomatic bradycardia, recurrent cardiogenic syncope, severe untreated sleep apnea, or history of Mobitz type 1 second-degree AV block (unless has functioning pacemaker).(1) Monitor blood pressure during treatment.(1)

DISCUSSION: Initiation of etrasimod treatment has been associated with transient atrioventricular (AV) conduction delays. The AV conduction delays manifested as first or second degree AV block (prolonged PR interval on ECG), which occurred in 0.7% of etrasimod treated patients in UC-1 and in 0.8% of patients in UC-2 and UC-3 compared to 0% for placebo in all studies.(1)

Agents That Cause Bradycardia/Ponesimod

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Initiation of ponesimod has caused transient decreases in heart rate and atrioventricular conduction delays after the first dose. Decreases in heart rate start within the first hour and maximal decrease in heart rate was seen at approximately 2-4 hours. The first dose has also been associated with heart block. Additional agents that cause bradycardia further increase the risk for symptomatic bradycardia.(1)

CLINICAL EFFECTS: The heart rate lowering effect of ponesimod is transient and is usually seen with the first dose. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsade de pointes.(1)

PREDISPOSING FACTORS: Pre-existing cardiovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, history of torsades de pointes, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to siponimod initiation, or factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia, bradycardia, female gender, or advanced age) may increase risk for cardiovascular toxicity due to siponimod.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The prescribing information states ponesimod treatment should generally not be initiated in patients who are on concurrent therapy with additional agents that cause bradycardia. If treatment with ponesimod is considered, advice from a cardiologist should be sought regarding switching to non-heart rate lowering drugs or monitoring during treatment initiation. Treatment initiation recommendations include: - Obtain an ECG in all patients to determine whether preexisting conduction abnormalities are present. - In all patients, a dose titration is recommended for initiation of ponesimod treatment to help reduce cardiac effects. - In patients with sinus bradycardia (HR less than 55 bpm), first- or second-degree [Mobitz type I] AV block, or a history of myocardial infarction or heart failure with onset > 6 months prior to initiation, ECG testing and first dose monitoring is recommended. - Since significant bradycardia may be poorly tolerated in patients with history of cardiac arrest, cerebrovascular disease, uncontrolled hypertension, or severe untreated sleep apnea, ponesimod is not recommended in these patients. If treatment is considered, advice from a cardiologist should be sought prior to initiation of treatment in order to determine the most appropriate monitoring strategy. - Use of ponesimod in patients with a history of recurrent syncope or symptomatic bradycardia should be based on an overall benefit-risk assessment. If treatment is considered, advice from a cardiologist should be sought prior to initiation of treatment in order to determine the most appropriate monitoring. - If a titration dose is missed or if 4 or more consecutive daily doses are missed during maintenance treatment, reinitiate Day 1 of the dose titration and follow titration monitoring recommendations.(1)

DISCUSSION: Initiation of ponesimod treatment has been associated with transient atrioventricular (AV) conduction delays that follow a similar temporal pattern as the observed decrease in heart rate during dose titration. The AV conduction delays manifested in most of the cases as first-degree AV block (prolonged PR interval on ECG), which occurred in 3.4% of ponesimod treated patients and in 1.2% of patients receiving teriflunomide in Study 1. Second-degree or third-degree AV blocks have not been reported in patients in clinical trials. The conduction abnormalities typically were transient, asymptomatic, resolved within 24 hours, and did not require discontinuation of ponesimod treatment.(1)

Agents That Cause Bradycardia/Siponimod

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Initiation of siponimod has caused transient decreases in heart rate and atrioventricular conduction delays after the first dose. Decreases in heart rate start within the first hour and maximal decrease in heart rate was seen at approximately 3-4 hours. The first dose has also been associated with heart block. Additional agents that cause bradycardia further increase the risk for symptomatic bradycardia.(1)

CLINICAL EFFECTS: The heart rate lowering effect of siponimod is transient and is usually seen with the first dose. Bradycardia may be associated with an increase in the QTc interval, increasing the risk for torsade de pointes.(1)

PREDISPOSING FACTORS: Pre-existing cardiovascular disease (e.g. heart failure, ischemic heart disease, history of myocardial infarction, stroke, history of torsades de pointes, or heart block), severe untreated sleep apnea, a prolonged QTc interval prior to siponimod initiation, or factors associated with QTc prolongation (e.g. hypokalemia, hypomagnesemia, bradycardia, female gender, or advanced age) may increase risk for cardiovascular toxicity due to siponimod.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2)

PATIENT MANAGEMENT: The prescribing information states siponimod treatment should generally not be initiated in patients who are concurrent therapy with additional agents that cause bradycardia. If treatment with siponimod is considered, advice from a cardiologist should be sought regarding switching to non-heart rate lowering drugs or recommendations for monitoring for treatment initiation. Treatment initiation recommendations include: - Obtain an ECG in all patients to determine whether preexisting conduction abnormalities are present. - In all patients, a dose titration is recommended for initiation of siponimod treatment to help reduce cardiac effects. - In patients with sinus bradycardia (HR less than 55 bpm), first- or second-degree [Mobitz type I] AV block, or a history of myocardial infarction or heart failure with onset > 6 months prior to initiation, ECG testing and first dose monitoring is recommended. - Since significant bradycardia may be poorly tolerated in patients with history of cardiac arrest, cerebrovascular disease, uncontrolled hypertension, or severe untreated sleep apnea, siponimod is not recommended in these patients. If treatment is considered, advice from a cardiologist should be sought prior to initiation of treatment in order to determine the most appropriate monitoring strategy. - Use of siponimod in patients with a history of recurrent syncope or symptomatic bradycardia should be based on an overall benefit-risk assessment. If treatment is considered, advice from a cardiologist should be sought prior to initiation of treatment in order to determine the most appropriate monitoring. - If a titration dose is missed or if 4 or more consecutive daily doses are missed during maintenance treatment, reinitiate Day 1 of the dose titration and follow titration monitoring recommendations.(1)

DISCUSSION: Initiation of siponimod treatment has been associated with transient atrioventricular (AV) conduction delays that follow a similar temporal pattern as the observed decrease in heart rate during dose titration. The AV conduction delays manifested in most of the cases as first-degree AV block (prolonged PR interval on ECG), which occurred in 5.1% of siponimod treated patients and in 1.9 % of patients receiving placebo in Study 1. Second-degree AV blocks, usually Mobitz type I (Wenckebach), have been observed at the time of treatment initiation with siponimod in less than 1.7% of patients in clinical trials. The conduction abnormalities typically were transient, asymptomatic, resolved within 24 hours, rarely required treatment with atropine, and did not require discontinuation of siponimod treatment.(1)

Alpha-2 Agonists/Tizanidine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Tizanidine is an alpha-2 agonist. Concurrent use with other alpha-2 agonists may result in additive effects on blood pressure.(1)

CLINICAL EFFECTS: Concurrent use of alpha-2 agonists and tizanidine may result in hypotension.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of tizanidine states concurrent use with other alpha-2 agonists is not recommended.(1) Patients receiving concurrent therapy should be monitored for hypotension. The risk of hypotension may be decreased by careful titration of tizanidine dosages and monitoring for hypotension prior to dose advancement. Counsel patients about the risk of orthostatic hypotension.(1)

DISCUSSION: Severe hypotension has been reported following the addition of tizanidine to existing lisinopril therapy.(2-4) Alpha-2 agonists linked include: clonidine, dexmedetomidine, guanabenz, guanadrel, guanethidine, guanfacine, methyldopa, and moxonidine.

Anticoagulants; Antiplatelets; Thrombolytics/Caplacizumab

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Bleeding has been reported with the use of caplacizumab.(1)

CLINICAL EFFECTS: Concurrent use of caplacizumab with anticoagulants, antiplatelets, or thrombolytics may increase the risk of hemorrhage.(1)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. hemophilia, coagulation factor deficiencies). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Avoid the use of caplacizumab with anticoagulants, antiplatelets, and thrombolytics. Interrupt caplacizumab therapy if clinically significant bleeding occurs. Patients may require von Willebrand factor concentrate to rapidly correct hemostasis. If caplacizumab is restarted, closely monitor for signs of bleeding.(1) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Bleeding has been reported with caplacizumab. In clinical studies, severe bleeding adverse reactions of epistaxis, gingival bleeding, upper gastrointestinal hemorrhage, and metrorrhagia were each reported in 1% of patients. Overall, bleeding events occurred in approximately 58% of patients on caplacizumab versus 43% of patients on placebo.(1) In post-marketing reports, cases of life-threatening and fatal bleeding were reported with caplacizumab.(1)

Ketorolac (Injectable)/Aspirin (< Or = 300 Mg)

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: There are two potential mechanisms: 1) Possible additive or synergistic pharmacodynamic side effects from concurrent NSAID use.(1,2) 2) Ketorolac is a reversible platelet inhibitor, while aspirin is an irreversible platelet inhibitor.

CLINICAL EFFECTS: Concurrent use of multiple doses of ketorolac with aspirin may result in increased risk for NSAID-related side effects such as bleeding.(1,2) Nonselective NSAIDs such as ketorolac may interfere with the antiplatelet effects of aspirin.(3)

PREDISPOSING FACTORS: Bleeding risk may increase due to disease (e.g. recent GI ulcer or bleed) or other concurrent drugs (e.g.anticoagulants, heparinoids). Elderly patients are at increased risk for severe GI events from ketorolac.(1,2) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (NSAIDs).

PATIENT MANAGEMENT: The manufacturer of prescription extended-release aspirin used for cardiovascular protection notes that concurrent treatment with NSAIDs may interfere with the antiplatelet effect of aspirin and increase the risk for NSAID associated bleeding or renal impairment, but does not contraindicate concurrent use.(3) However, manufacturers of ketorolac state that concurrent use of ketorolac with aspirin is contraindicated.(1,2) If concurrent therapy or ketorolac with low dose aspirin is needed, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Conduct periodic monitoring of renal function, especially in patients with preexisting renal impairment. Instruct patients to report any signs and symptoms of bleeding, such as unusual bruising; red or black, tarry stools; acute abdominal or joint pain and/or swelling.

DISCUSSION: Based upon similar pharmacodynamic effects and potentially cumulative risks for serious NSAID-related adverse events, manufacturers of ketorolac state the concurrent administration of ketorolac with other NSAIDs or aspirin is contraindicated.(1,2) Prescribing information for an FDA approved lower strength prescription aspirin product used for cardiovascular risk reduction describes potential interactions, but does not contraindicate concomitant NSAID use.(3)

Local Anesthetics/Long-Acting Bupivacaine

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Concurrent use of other local anesthetics or use of other local anesthetics within 96 hours following long-acting bupivacaine may result in additive neurologic and cardiovascular effects. Use of articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, and tetracaine may also increase the risk of methemoglobinemia.(1,2) Non-liposomal bupivacaine may impact the pharmacokinetic and/or physicochemical properties of the liposomal formulation when administered in the same syringe or used simultaneously unless the ratio of mg of non-liposomal bupivacaine to mg of bupivacaine liposomal does not exceed 1:2.(1) Local anesthetics other than bupivacaine may trigger the immediate release of bupivacaine from the liposomal formulation when administered together locally.(1)

CLINICAL EFFECTS: Concurrent or use of local anesthetics with 96 hours of use of long-acting bupivacaine may result in neurologic and cardiovascular toxicity. Use of articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, and tetracaine may also result in methemoglobinemia.(1,2) Non-liposomal bupivacaine may impact the pharmacokinetic and/or physicochemical properties of the liposomal formulation when administered in the same syringe or used simultaneously unless the ratio of mg of non-liposomal bupivacaine to mg of bupivacaine liposomal does not exceed 1:2.(1) Local anesthetics other than bupivacaine may trigger the immediate release of bupivacaine from the liposomal formulation when administered together locally.(1)

PREDISPOSING FACTORS: Use of additional agents that are associated with methemoglobinemia may further increase the risk of methemoglobinemia.(1) Patients who are at increased risk of developing methemoglobinemia include those with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants under 6 months of age, and concurrent exposure to oxidizing agents or their metabolites are more susceptible to developing clinical manifestations of the condition. If local anesthetics must be used in these patients, close monitoring for symptoms and signs of methemoglobinemia is recommended.(1)

PATIENT MANAGEMENT: Avoid the use of other local anesthetics within 96 hours following the administration of long-acting bupivacaine. In patients for whom use is required, monitor for neurologic and cardiovascular effects. Also monitor for methemoglobinemia with use of articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, and tetracaine.(1,2) Non-liposomal bupivacaine may be administered in the same syringe as bupivacaine liposomal or injected immediately before bupivacaine liposomal as long as the ratio of mg of non-liposomal bupivacaine to mg of bupivacaine liposomal does not exceed 1:2.(1) Lidocaine may be administered 20 minutes or more prior to bupivacaine. It is unknown if other local anesthetics may be used without compromising the release characteristic of bupivacaine liposomal.(1)

DISCUSSION: Concurrent use of other local anesthetics or use of other local anesthetics within 96 hours following long-acting bupivacaine may result in additive neurologic and cardiovascular effects. Use of articaine, benzocaine, bupivacaine, lidocaine, mepivacaine, prilocaine, procaine, ropivacaine, and tetracaine may also increase the risk of methemoglobinemia.(1,2) Non-liposome bupivacaine may impact the pharmacokinetic and/or physicochemical properties of the liposomal formulation when administered in the same syringe or used simultaneously unless the ratio of mg of non-liposomal bupivacaine to mg of bupivacaine liposomal does not exceed 1:2.(1) Local anesthetics other than bupivacaine may trigger the immediate release of bupivacaine from the liposomal formulation when administered together locally. Lidocaine may be administered 20 minutes or more prior to bupivacaine. It is unknown if other local anesthetics may be used without compromising the release characteristic of bupivacaine liposomal.(1)

Non-Steroidal Anti-Inflammatory Drugs/Inotersen

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Inotersen causes reductions in platelet count that may result in sudden and unpredictable thrombocytopenia. Inotersen can also cause glomerulonephritis and renal toxicity. NSAIDs can impair thromboxane-dependent platelet aggregation by blocking the formation of thromboxane A2. Concurrent administration with NSAIDs may also result in additive or synergistic effects on renal function.(1)

CLINICAL EFFECTS: Concurrent use of inotersen with NSAIDs may result in additive or synergistic effects, including fatal and non-fatal intracranial hemorrhage, or renal toxicity.(1)

PREDISPOSING FACTORS: The risk for bleeding episodes may also be greater in patients greater than 60 years or have a prior history of major bleeding events. Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding. Patients with pre-existing renal impairment.

PATIENT MANAGEMENT: Inotersen should be administered with caution in patients receiving NSAIDs. If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Monitor platelet count frequently. If platelet count is less than 50, stop inotersen treatment and consider discontinuation of NSAID. Monitor for signs and symptoms of thrombocytopenia; such as, unusual or prolonged bleeding (petechiae, easy bruising, hematoma, subconjunctival bleeding, gingival bleeding, epistaxis, hemoptysis, irregular or heavier than normal menstrual bleeding, hematemesis, hematuria, hematochezia, melena), neck stiffness, or atypical severe headache. Monitor renal function closely.

DISCUSSION: In a clinical study, platelet counts below 100 occurred in 25% of inotersen-treated patients, compared with 2% of patients on placebo. Platelet counts below 75 occurred in 14% of inotersen-treated patients, compared to no patients on placebo. In study 1 and its extension study, 39% of inotersen-treated patients with a baseline platelet count below 200 had a nadir platelet count below 75, compared to 6% of patients with baseline platelet counts 200 or higher. Three inotersen-treated patients (3%) had sudden severe thrombocytopenia (platelet count below 25). One patient experienced a fatal intracranial hemorrhage.(1) The safety of inotersen has not been studied in patients receiving other known potentially nephrotoxic agents.(1) Inotersen is only available through a Tegsedi REMS program because of the risk of severe thrombocytopenia and the risk of glomerulonephritis.(1)

Nsaids/Methotrexate; Pralatrexate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: The exact mechanism is unknown. NSAID-induced inhibition of prostaglandin synthesis may decrease renal perfusion rate and therefore inhibit methotrexate and pralatrexate clearance. NSAIDs may also compete for renal secretion with methotrexate and pralatrexate. Since methotrexate is not extensively protein bound, displacement of methotrexate by NSAIDs is unlikely to have altered methotrexate kinetics.

CLINICAL EFFECTS: Increased levels of methotrexate and pralatrexate, with increased effects, leading to increased risk of severe neurotoxicity, stomatitis, and myelosuppression, including neutropenia.

PREDISPOSING FACTORS: Risk factors for methotrexate toxicity include: - High-dose oncology regimens - Impaired renal function, ascites, or pleural effusions

PATIENT MANAGEMENT: Avoid the use of NSAIDs with high dose methotrexate therapy.(1) If both drugs must be given, monitor methotrexate levels and patient response carefully. Consider extending leucovorin rescue duration. Use caution when administering NSAIDs with low dose methotrexate therapy. (1) Administration of NSAIDs with pralatrexate requires close monitoring for toxicity.(2)

DISCUSSION: A retrospective review documented four cases of methotrexate toxicity during concurrent administration of ketoprofen and methotrexate in 36 patients. Three cases were fatalities.(3) In contrast, a four-way cross-over study in ten subjects found no effect on methotrexate oral or renal clearance by ketoprofen, piroxicam, or flurbiprofen.(4) In a study in 19 subjects, the concurrent administration of methotrexate and piroxicam resulted in a decrease in methotrexate maximum concentration (Cmax) but no other changes in methotrexate kinetics.(5) Another three-way cross-over study in six patients showed no effect by flurbiprofen or ibuprofen on methotrexate kinetics.(6) In contrast, administration of ibuprofen to nine patients resulted in a 39% decrease in methotrexate total clearance and a 40% decrease in methotrexate renal clearance.(7) Information on naproxen is also conflicting. In another arm of the earlier study (7), the administration of naproxen in nine patients decreased methotrexate total clearance by 22%, but had no significant effects on methotrexate renal clearance. In another study in nine subjects, methotrexate altered naproxen kinetics by greater than 30% in six subjects, although these changes were not statistically significant. Naproxen altered methotrexate kinetics by greater than 30% in four subjects, although these changes were also not statistically significant.(8) In contrast, the administration of naproxen with methotrexate in 15 subjects showed no significant effects on methotrexate oral or renal clearance.(9) A study in 19 subjects found that the concurrent administration of etodolac and methotrexate decreased methotrexate Cmax and increased methotrexate mean residence time. There were no changes in methotrexate clearance or area-under-curve (AUC) and no toxicity was observed.(10) A study in 12 patients showed no significant effects of sulindac on methotrexate kinetics unless one patient who had low baseline clearance of methotrexate was excluded from analysis.(11) A study in seven children examined the effects of the children's usual NSAID on methotrexate kinetics. NSAIDs were naproxen, tolmetin, and indomethacin. Methotrexate half-life increased during NSAID administration. There were no significant changes in methotrexate clearance, AUC or volume of distribution. There was inter-subject variably in response. In six of seven patients, NSAID administration increased methotrexate AUC 19-140%.(12) Case reports have documented an interaction between methotrexate and phenylbutazone (13), indomethacin (14), flurbiprofen (15), and naproxen (16,17); however, one naproxen report (16) is complicated by the fact that the patient took 27.5 mg methotrexate in one week instead of 2.5 mg three times weekly. Because of the conflicting data and wide patient variability, caution is warranted during concurrent administration of methotrexate and any NSAID.

Nsaids; Salicylates/Sodium Phosphate Bowel Cleanser

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Bowel cleansing with sodium phosphate causes dehydration, decreased intravascular volume and hyperphosphatemia, which increases phosphate levels in the renal tubules. Abnormally high levels of calcium and phosphate in the renal tubules may precipitate out, resulting in renal injury.(1)

CLINICAL EFFECTS: Use of sodium phosphate for bowel cleansing in patients maintained on nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the risk of acute phosphate nephropathy, which is an acute kidney injury associated with deposits of calcium phosphate crystal in the renal tubules that may result in permanent renal function impairment. Acute phosphate nephropathy presents as acute kidney injury with minimal proteinuria and a bland urine sediment.(2) Use of oral sodium phosphate products at laxative doses has not been associated with acute kidney injury.(3)

PREDISPOSING FACTORS: Patients who may be at an increased risk of acute phosphate nephropathy include those who are over age 55; are hypovolemic or have decreased intravascular volume; have baseline kidney disease, bowel obstruction, or active colitis; and who are using medications that affect renal perfusion or function (such as diuretics, ACE inhibitors, angiotension receptor blockers [ARBs]), and NSAIDs.(2)

PATIENT MANAGEMENT: If possible, use an alternative agent for bowel cleansing.(1) Use sodium phosphate products with caution in patients taking medications that affect kidney function or perfusion, such as ACE inhibitors or ARBs. Obtain baseline and post-procedure labs (electrolytes, calcium, phosphate, BUN, creatinine, and [in smaller, frail individuals] glomerular filtration rate). Instruct patients to drink sufficient quantities of clear fluids before, during, and after bowel cleansing and to avoid other laxatives that contain sodium phosphate. Consider hospitalization and intravenous hydration during bowel cleansing to support frail patients who may be unable to drink an appropriate volume of fluid or who may be without assistance at home.(2) Use of an electrolyte solution for rehydration may decrease the risk of acute phosphate nephropathy.(4,5)

DISCUSSION: Since May 2006, the FDA has received 20 reports of acute phosphate nephropathy associated with the use of Osmo Prep. Concomitant medications included ACE inhibitors or ARBs (11), diuretics (6), and NSAIDs (4).(2) In a retrospective review of colonoscopy patients, simultaneous use of ACE inhibitors or ARBs significantly increased the risk of acute kidney injury from oral sodium phosphate. Diuretic use was also a risk factor.(6) In a case series study of 21 cases of acute phosphate nephropathy in patients who had used oral sodium phosphate, 14 patients received an ACE inhibitor or ARB, 4 used a diuretic, and 3 used an NSAID.(7) Cases have also been reported with rectal products.(8)

Selected Nephrotoxic Agents/Colistimethate

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Colistimethate can cause nephrotoxicity.(1,2) Concurrent administration of other nephrotoxic agents may result in an increased risk of nephrotoxicity.(1) It is suspected that cephalothin interferes with the excretion of colistimethate resulting in enhanced nephrotoxicity.(2,3)

CLINICAL EFFECTS: Concurrent use of colistimethate with other nephrotoxic agents may result in additive nephrotoxic effects.

PREDISPOSING FACTORS: Factors predisposing to nephrotoxicity include higher cumulative doses of colistimethate, longer treatment duration, hypovolemia, and critical illness.

PATIENT MANAGEMENT: Concurrent use of potentially nephrotoxic agents with colistimethate should be avoided.(1,2) If concurrent use is necessary, it should be undertaken with great caution.(1)

DISCUSSION: In a case control study of 42 patients on intravenous colistimethate sodium, NSAIDs were identified as an independent risk factor for nephrotoxicity (OR 40.105, p=0.044).(4) In 4 case reports, patients developed elevated serum creatinine and blood urea nitrogen following concurrent colistimethate and cephalothin (3 patients) or when colistimethate followed cephalothin therapy (1 patient).(3) A literature review found that individual nephrotoxic agents, including aminoglycosides, vancomycin, amphotericin, IV contrast, diuretics, ACE inhibitors, ARBs, NSAIDs, and calcineurin inhibitors, were not consistently associated with additive nephrotoxicity when used with colistimethate. However, when multiple agents (at least 2 additional potential nephrotoxins) were used concurrently, there was a significant correlation to colistimethate nephrotoxicity.(5)

Selected Nephrotoxic Agents/Foscarnet

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: Foscarnet is nephrotoxic. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1) Concurrent intravenous pentamidine may also result in hypocalcemia.(1)

CLINICAL EFFECTS: Concurrent use of foscarnet with nephrotoxic agents such as acyclovir, adefovir, intravenous aminoglycosides, amphotericin B, cyclosporine, methotrexate, non-steroidal anti-inflammatory agents, intravenous pentamidine, tacrolimus, tenofovir, vancomycin and voclosporin may result in renal toxicity.(1) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, and streptozocin.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The US manufacturer of foscarnet state that concurrent administration of potentially nephrotoxic agents such as acyclovir, intravenous aminoglycosides, amphotericin B, cyclosporine, methotrexate, tacrolimus, and intravenous pentamidine should be avoided.(1) Other nephrotoxic agents include adefovir, capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, non-steroidal anti-inflammatory agents, streptozocin, tenofovir, vancomycin and voclosporin. If concurrent therapy is warranted, monitor renal function closely. In patients receiving concurrent foscarnet and pentamidine, also monitor serum calcium levels and instruct patients to report severe muscle spasms, mental/mood changes, and/or seizures.(1)

DISCUSSION: The safety of foscarnet has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is the major toxicity of foscarnet.(1)

Selected Nsaids; Aspirin (>325 Mg)/Pemetrexed

SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction.

MECHANISM OF ACTION: NSAIDs may decrease the clearance of pemetrexed.(1) This decreased clearance may be the result of chronic renal toxicity from NSAIDs or NSAIDs may compete with pemetrexed for tubular secretion.(2)

CLINICAL EFFECTS: Concurrent use of pemetrexed and NSAIDs may result in elevated levels of and toxicity from pemetrexed, including myelosuppression, neutropenia, renal toxicity, and gastrointestinal toxicity.(1)

PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with mild to moderate renal insufficiency (creatinine clearance (CrCl) of 45 ml/min to 79 ml/min) and/or patients taking long acting NSAIDs. (1)

PATIENT MANAGEMENT: In patients with normal renal function (CrCl equal to or greater than 80 ml/min), ibuprofen (400 mg 4 times daily) can be administered with pemetrexed. Aspirin in low to moderate doses (325 mg every 6 hours) does not affect the pharmacokinetics of pemetrexed.(1) In patients with mild to moderate renal insufficiency (CrCl from 45 ml/min to 79 ml/min), NSAIDs with short half-lives should be avoided for 2 days before, the day of, and 2 days after pemetrexed administration. Ibuprofen should be administered with caution in these patients.(1) NSAIDs and salicylates with long half-lives should be avoided for at least 5 days before, the day of, and 2 days following pemetrexed administration in all patients.(1,2) If NSAIDs are required, patients should be monitored for pemetrexed toxicity, especially myelosuppression, renal toxicity, and gastrointestinal toxicity.(1)

DISCUSSION: In patients with normal renal function, ibuprofen (400 mg 4 times daily) decreased the clearance of pemetrexed by 20% and increased its area-under-curve (AUC) by 20%.(1) In a Phase I clinical trial, two patients receiving high dose pemetrexed therapy experienced severe toxicity, both were receiving a NSAID. Following these reports, all patients were required to stop aspirin or other NSAIDs 2 days before and not resume these agents until 2 days after pemetrexed.(2) In two randomized, controlled cross-over trials, 27 cancer patients with a creatinine clearance (CrCl) less than or equal to 60 ml/min received pemetrexed (500 mg/m2) infusion on Day 1 of a 21-day cycle and either aspirin 325 mg or ibuprofen 400 mg orally every 6 hours starting 2 days before pemetrexed administration. Coadministration of aspirin did not affect pemetrexed pharmacokinetics. Ibuprofen decreased the clearance of pemetrexed by 16%, increased its maximum concentration (Cmax) by 15%, and increased the AUC by 20%.(3) Aspirin products linked to this monograph are single ingredient aspirin products with greater than 325 mg strength, and aspirin combination products (e.g. opioid-aspirin or cough/cold/allergy products) with a reasonable likelihood of a total daily aspirin dose > or = 1,300 mg per day.

Moderate Interaction: Assess the risk to the patient and take action as needed.

Agents With Hyponatremia Risk/Desmopressin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Carbamazepine, chlorpromazine, lamotrigine, NSAIDs, opioids, SSRIs, thiazide diuretics, and/or tricyclic antidepressants increase the risk of hyponatremia.(1-3)

CLINICAL EFFECTS: Concurrent use may increase the risk of hyponatremia with desmopressin.(1-3)

PREDISPOSING FACTORS: Predisposing factors for hyponatremia include: polydipsia, renal impairment (eGFR < 50 ml/min/1.73m2), illnesses that can cause fluid/electrolyte imbalances, age >=65, medications that cause water retention and/or increase the risk of hyponatremia (glucocorticoids, loop diuretics).

PATIENT MANAGEMENT: The concurrent use of agents with a risk of hyponatremia with desmopressin may increase the risk of hyponatremia. If concurrent use is deemed medically necessary, make sure serum sodium levels are normal before beginning therapy and consider using the desmopressin nasal 0.83 mcg dose. Consider measuring serum sodium levels more frequently than the recommended intervals of: within 7 days of concurrent therapy initiation, one month after concurrent therapy initiation and periodically during treatment. Counsel patients to report symptoms of hyponatremia, which may include: headache, nausea/vomiting, feeling restless, fatigue, drowsiness, dizziness, muscle cramps, changes in mental state (confusion, decreased awareness/alertness), seizures, coma, and trouble breathing. Counsel patients to limit the amount of fluids they drink in the evening and night-time and to stop taking desmopressin if they develop a stomach/intestinal virus with nausea/vomiting or any nose problems (blockage, stuffy/runny nose, drainage).(1)

DISCUSSION: In clinical trials of desmopressin for the treatment of nocturia, 4 of 5 patients who developed severe hyponatremia (serum sodium <= 125 mmol/L) were taking systemic or inhaled glucocorticoids. Three of these patients were also taking NSAIDs and one was receiving a thiazide diuretic.(2) Drugs associated with hyponatremia may increase the risk, including loop diuretics, carbamazepine, chlorpromazine, glucocorticoids, lamotrigine, NSAIDs, opioids, SSRIs, thiazide diuretics, and/or tricyclic antidepressants.(1,3-4)

Anticoagulants; Antiplatelets/Fruquintinib; Surufatinib

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Bleeding has been reported with the use of fruquintinib and surufatinib.(1,2)

CLINICAL EFFECTS: Concurrent use of fruquintinib or surufatinib with either anticoagulants or antiplatelets may increase the risk of hemorrhage.(1,2)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Patients receiving concurrent therapy with fruquintinib and anticoagulants and/or antiplatelets should be closely monitored for changes in platelet count or in International Normalized Ratio (INR). If a serious bleeding event occurs, the manufacturer recommends permanent discontinuation of fruquintinib.(1) Patients receiving concurrent therapy with surufatinib and anticoagulants and/or antiplatelets should be closely monitored for changes in platelet count or in INR.If a serious bleeding event occurs, the manufacturer recommends permanent discontinuation of surufatinib.(2) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Bleeding has been reported with fruquintinib in three randomized, double-blinded, placebo-controlled clinical trials. The incidence of grade 1 and grade 2 bleeding events was 28.2%, including gastrointestinal bleeding (10.9%), hematuria (10.6%), and epistaxis (7.5%). The incidence of grade 3 or higher bleeding events was 2.1% and included gastrointestinal bleeding (1.6%) and hemoptysis (0.5%).(1) Bleeding has been reported with surufatinib in clinical trials. Grade 1 and 2 bleeding events included gastrointestinal bleeding, blood in the urine, and gum bleeding. The incidence of grade 3 or greater bleeding events was 4.5%, including gastrointestinal hemorrhage (1.9%), and cerebral hemorrhage (1.1%). Fatalities due to bleeding were reported in 0.3% of patients. The incidence of permanent discontinuation due to bleeding was 2.6% and the incidence of suspension of surufatinib due to bleeding was 3.8%.(2)

Anticoagulants; Antiplatelets/Obinutuzumab

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Severe and life-threatening thrombocytopenia has been reported during obinutuzumab therapy.(1) Anticoagulants and antiplatelets may have an additive risk of bleeding.

CLINICAL EFFECTS: Concurrent use of obinutuzumab with anticoagulants or antiplatelet agents may result in additive or synergistic effects, including fatal and non-fatal hemorrhage.(1)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Monitor all patients frequently for thrombocytopenia and signs of bleeding. Consider withholding concomitant anticoagulants and antiplatelets, especially during the first cycle of obinutuzumab.(1) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: Obinutuzumab with chemotherapy has been reported to cause severe and life-threatening thrombocytopenia. Fatal hemorrhagic events have occurred in patients with NHL and CLL during obinutuzumab therapy, including during Cycle 1.(1)

Anticoagulants; Antiplatelets/Plasminogen

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Bleeding has been reported with the use of plasminogen.(1)

CLINICAL EFFECTS: Concurrent use of plasminogen with either anticoagulants or antiplatelets may increase the risk of active bleeding during plasminogen therapy, including bleeding from mucosal disease-related lesions that may manifest as gastrointestinal (GI) bleeding, hemoptysis, epistaxis, vaginal bleeding, or hematuria.(1)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Patients receiving concurrent therapy with plasminogen and anticoagulants and/or antiplatelets should be closely monitored during plasminogen therapy for active bleeding from mucosal disease-related lesions, including GI bleeding, hemoptysis, epistaxis, vaginal bleeding, or hematuria.(1) Prior to initiation of treatment with plasminogen, confirm healing of lesions or wounds suspected as a source of a recent bleeding event. Monitor patients during and for 4 hours after infusion when administering plasminogen with concurrent anticoagulants, antiplatelet drugs, or other agents which may interfere with normal coagulation.(1) If patient experiences uncontrolled bleeding (defined as any gastrointestinal bleeding or bleeding from any other site that persists longer than 30 minutes), seek emergency care and discontinue plasminogen immediately.(1) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Plasminogen has not been studied in patients at an increased risk of bleeding. Bleeding has been reported with plasminogen in a two single-arm, open-label clinical trials as well as in compassionate use programs. The incidence of hemorrhage in patients with Plasminogen Deficiency Type 1 was 16% (3/19 patients).(1) One of the bleeding events occurred two days after receiving the second dose of plasminogen in a patient with a recent history of GI bleeding due to gastric ulcers. The patient received plasminogen through a compassionate use program and the dose was 6.6 mg/kg body weight every 2 days. Endoscopy showed multiple ulcers with one actively bleeding ulcer near the pylorus.(1)

Anticoagulants; Antiplatelets/Tisotumab

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Bleeding, including hemorrhage, has been reported with the use of tisotumab.(1)

CLINICAL EFFECTS: Concurrent use of tisotumab with either anticoagulants, antiplatelets, or NSAIDs may increase the risk of hemorrhage.(1)

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: Patients receiving concurrent therapy with tisotumab and anticoagulants, antiplatelets, and/or NSAIDs should be closely monitored for signs and symptoms of bleeding and changes in platelet count or International Normalized Ratio (INR). For patients experiencing pulmonary or central nervous system (CNS) hemorrhage, permanently discontinue tisotumab. For grade 2 or greater hemorrhage in any other location, withhold until bleeding has resolved, blood hemoglobin is stable, there is no bleeding diathesis that could increase the risk of continuing therapy, and there is no anatomical or pathologic condition that can increase the risk of hemorrhage. After resolution, either resume treatment or permanently discontinue tisotumab.(1) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Hemorrhage occurred in 62% of patients with cervical cancer treated with tisotumab across clinical trials. The most common all grade hemorrhage adverse reactions were epistaxis (44%), hematuria (10%), and vaginal hemorrhage (10%). Grade 3 hemorrhage occurred in 5% of patients.(1)

Clonidine/Beta-Blockers

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Withdrawal of clonidine triggers increased catecholamine release. Beta-blockers inhibit the vasodilation mediated by the beta 2 receptor, leaving the vasoconstriction mediated by the alpha 2 receptor unopposed. In addition, concurrent use is expected to produce additive effects on blood pressure and heart rate requiring standard monitoring precautions.

CLINICAL EFFECTS: Severe hypertension may occur upon abrupt discontinuation of clonidine in patients receiving both clonidine and beta-blockers. In addition, concurrent use is expected to produce additive effects on blood pressure and heart rate requiring standard monitoring precautions.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: In a patient receiving both drugs, discontinuation of the beta-blocker prior to clonidine may decrease the occurrence of rebound hypertension. If clonidine is discontinued first, rebound hypertension can be treated by restarting the clonidine or by the IV administration of phentolamine, phenoxybenzamine or prazosin. When adding either of these agents to the drug regimen of the patient, monitor blood pressure. Since labetalol has both alpha and beta activity, administration of labetalol may prevent rebound hypertension in patients undergoing clonidine withdrawal, although conflicting reports exist. In addition, concurrent use is expected to produce additive effects on blood pressure and heart rate requiring standard monitoring precautions.

DISCUSSION: Increased blood pressure has been observed in patients following: 1) the discontinuation of clonidine in patients receiving beta-blockers, 2) the replacement of clonidine therapy with beta-blockers, 3) the simultaneous discontinuation of both drugs. Conflicting reports exist on the development of increased blood pressure after clonidine withdrawal in patients receiving labetalol. Patients receiving labetalol who are being withdrawn from clonidine should still be closely monitored.

Clonidine/Tricyclic Compounds; Mirtazapine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Clonidine decreases blood pressure via alpha-2 agonism.(1) Tricyclic compounds(2) and mirtazapine(3) antagonize alpha-2, which may result in a loss of effect of clonidine.

CLINICAL EFFECTS: The concurrent use of clonidine and tricyclic compounds(1,3,4-16) and mirtazapine(3,17) may result in decreased effectiveness of clonidine and hypertensive crisis.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: If possible, avoid concurrent use of clonidine with tricyclic compounds or mirtazapine. Consider using an alternative agent in patients maintained on clonidine. If concurrent administration is warranted, blood pressure should be carefully monitored, particularly in the first two weeks of therapy, when this interaction is most likely to occur. The dosage of clonidine may need to be adjusted or the tricyclic compound or mirtazapine may need to be discontinued.

DISCUSSION: This interaction has been reported in patients receiving amitriptyline,(6) clomipramine,(7,8) desipramine,(2,9-11) imipramine(12-16), and protriptyline.(11) In one patient, a hypertensive crisis resulted. Other patients experienced a decrease in blood pressure control. A controlled trial demonstrated a decrease in anti-hypertensive effect when desipramine was added to a clonidine regimen. This decrease in hypertensive-control may be overcome by increasing the dose of clonidine and monitoring blood pressure closely. Cyclobenzaprine is structurally related to the tricyclic antidepressants and, especially at higher dosages, has similar effects.(18) Therefore, it is prudent to consider cyclobenzaprine in this interaction. Hypertensive crisis has been reported during concurrent clonidine and mirtazapine therapy.(3,17) Mianserin(19,20) and maprotiline,(21) tetracyclic antidepressants, have been shown not to affect the antihypertensive effects of clonidine.

Nsaids/Corticosteroids

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Concurrent use of NSAIDs and corticosteroids result in additive risk of GI ulceration.

CLINICAL EFFECTS: Concurrent use of NSAIDs and corticosteroids may increase the incidence and/or severity of GI irritation or ulceration, including increasing the risk for bleeding.

PREDISPOSING FACTORS: Risk of GI bleed may be increased in patients who are of older age, in poor health status, or who use alcohol or smoke. Risk may also be increased by concurrent use of anticoagulants, antiplatelets, selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs); with longer duration of NSAID use; and with prior history of peptic ulcer disease and/or GI bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia, advanced liver disease).

PATIENT MANAGEMENT: Monitor patients receiving concurrent therapy carefully for signs of gastrointestinal ulceration. Use the lowest effective NSAID dose for the shortest duration possible. If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Instruct patients to report signs of GI bleeding such as black, tarry stools; "coffee ground" vomit; nausea; or stomach/abdominal pain.

DISCUSSION: Concurrent use of NSAIDs and corticosteroids increase the risk of GI bleeding.

Nsaids; Aspirin (Non-Cardioprotective)/Beta-Blockers

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Unknown; however, possibly related to inhibition of prostaglandin by NSAIDs.

CLINICAL EFFECTS: The antihypertensive action of beta-blockers may be decreased.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Monitor patient's blood pressure and adjust the dose of the beta-blocker as needed.

DISCUSSION: Concurrent administration of beta-blockers and NSAIDs has been associated with a clinically significant loss in antihypertensive response. The magnitude of the effect of NSAIDs on control of blood pressure by beta-blockers needs to be determined for each anti-inflammatory agent. One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.

Nsaids; Aspirin (Non-Cardioprotective)/Metoprolol

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Unknown; however, possibly related to inhibition of prostaglandin by NSAIDs.

CLINICAL EFFECTS: The antihypertensive action of metoprolol may be decreased.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Monitor patient's blood pressure and adjust the dose of metoprolol as needed.

DISCUSSION: Concurrent administration of metoprolol and NSAIDs has been associated with a clinically significant loss in antihypertensive response. The magnitude of the effect of NSAIDs on control of blood pressure by beta-blockers needs to be determined for each anti-inflammatory agent. One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.

Nsaids; Salicylates/Aliskiren

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The exact mechanism is unknown. It is believed to be related to inhibition of prostaglandin synthesis by the NSAIDs. Use of an NSAID in combination with aliskiren, whose hypotensive effects may be related to the increase in hypotensive prostaglandins, may negate any decrease in blood pressure.

CLINICAL EFFECTS: Concurrent use of aliskiren with NSAIDs may result in decreased antihypertensive effects. In patients with existing renal impairment, the use of these agents together may also result in further deterioration of renal clearance caused by renal hypoperfusion.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Patients maintained on aliskiren should be monitored for a loss of blood pressure control and a change in renal function if an NSAID is added to their regimen. Patients receiving concurrent therapy may require higher doses of aliskiren. If blood pressure control cannot be achieved or if the patient's renal function deteriorates, the NSAID may need to be discontinued. Patients should be monitored for hypotension if NSAIDs are withdrawn from concurrent aliskiren therapy.

DISCUSSION: Indomethacin has been shown to inhibit the antihypertensive effect of captopril, cilazapril, enalapril, losartan, perindopril, and valsartan. Ibuprofen has been shown to decrease the antihypertensive effects of captopril. Two separate case reports describe individuals suspected of ACEI-associated angioedema precipitated by NSAIDs. Both cases reported symptom resolution after cessation of the NSAID. Studies have shown that sulindac does not affect the antihypertensive effects of captopril and enalapril.

Nsaids; Salicylates/Lithium

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Decreased renal excretion of lithium, possibly resulting from NSAID-induced prostaglandin inhibition.

CLINICAL EFFECTS: May observe increased lithium toxicity.

PREDISPOSING FACTORS: Risk factors for lithium toxicity include: renal impairment or worsening of existing renal disease, dehydration, low sodium diet, and concomitant use of multiple medications which may impair renal elimination of lithium (e.g. ARBs, ACE Inhibitors, NSAIDs, diuretics). Patients who require higher therapeutic lithium levels to maintain symptom control are particularly susceptible to these factors.

PATIENT MANAGEMENT: The magnitude of this interaction is highly variable. Patients with predisposing factors, e.g. dehydration, renal impairment, or concurrent use of other agents which may impair lithium elimination, are expected to have a higher risk for lithium toxicity. If both drugs are administered, monitor plasma lithium levels and observe the patient for signs and symptoms of lithium toxicity or changes in renal function. Full effects of the addition or an increase in NSAID dose may not be seen for one to two weeks. Adjust the dose of lithium accordingly. If lithium is to be started in a patient stabilized on chronic NSAID therapy, consider starting with a lower lithium dose and titrate slowly as half-life may be prolonged. Monitor lithium concentrations until stabilized on the combination. Counsel the patient to contact their prescriber before starting an OTC NSAID. Assure that patients are familiar with signs and symptoms of lithium toxicity (e.g. new or worsening tremor, nausea/vomiting, diarrhea, ataxia, or altered mental status) and to report signs and symptoms of toxicity.

DISCUSSION: Numerous studies and case reports have been documented that administration of a NSAID to a patient stabilized on lithium therapy may result in increased serum lithium levels and possible toxicity. Full effects may take 1 to 2 weeks to develop and may persist for a week after the NSAID is discontinued.

Nsaids; Salicylates/Sparsentan

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Sparsentan is an endothelin and angiotensin II receptor antagonist.(1) Angiotensin II receptor blockers can cause vasodilation of the efferent renal arteriole which may result in decreased glomerular filtration rate. NSAIDs inhibit prostaglandin synthesis which can lead to afferent arteriolar vasoconstriction.

CLINICAL EFFECTS: Concurrent use of sparsentan with NSAIDs (including selective COX-2 inhibitors) may result in renal hypoperfusion and deterioration of renal clearance, including possible acute kidney injury (AKI). These effects are usually reversible.(1)

PREDISPOSING FACTORS: Patients older than 75 years old, with renal artery stenosis, chronic kidney disease, severe congestive heart failure, or volume depletion (including from diuretic use and dehydration) may be at greater risk for AKI.(1-3)

PATIENT MANAGEMENT: Monitor for signs of worsening renal function if an NSAID (including selective COX-2 inhibitors) is used concurrently with sparsentan. If renal function deteriorates, the NSAID may need to be discontinued.(1)

DISCUSSION: In a computational study, the risk of AKI using triple therapy with a diuretic, renin-angiotensin system (RAS) inhibitor, and NSAID was assessed. The study found the following factors may increase an individual's susceptibility to AKI: low water intake, drug sensitivity, greater than 75 years of age, and renal impairment.(2,3) In an observational study, current use of a triple therapy combination was associated with an increased rate of acute kidney injury (rate ratio (RR) 1.31, 95% confidence interval (CI) 1.12-1.53). The highest risk of AKI associated with triple therapy were observed in the first 30 days of use (RR 1.82, CI 1.35-2.46).(4)

Ropivacaine/Strong Cyp1a2 Inhibitors

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Strong CYP1A2 inhibitors may inhibit the metabolism of ropivacaine.

CLINICAL EFFECTS: Concurrent use of a strong CYP1A2 inhibitor may result in increased levels of and toxicity from ropivacaine.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: In patients receiving concurrent strong CYP1A2 inhibitors and ropivacaine, monitor patients closely for signs of toxicity.

DISCUSSION: In a double-blind, randomized, cross-over study in 9 healthy subjects, ciprofloxacin (500 mg twice daily) decreased the clearance of a single dose of ropivacaine (0.6 mg/kg) by 31%.(1) In a double-blind, randomized, cross-over study in 8 healthy subjects, fluvoxamine (100 mg daily) increased the area-under-curve (AUC) of a single dose of ropivacaine (0.6 mg/kg) by 3.7-fold.(2) In a randomized, cross-over study in 12 healthy subjects, fluvoxamine (25 mg daily) increased the clearance of a single dose of ropivacaine (40 mg) by 68%. Ropivacaine half-life almost doubled.(3) Strong inhibitors of CYP1A2 include angelica root (angelica dahurica radix), enasidenib, enoxacin, fluvoxamine, and rofecoxib.(4,5)

Selected Anticoagulants; Antiplatelets/Ibrutinib

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Ibrutinib administration lowers platelet count in the majority of patients.(1,2) In addition, ibrutinib has been shown to inhibit collagen-mediated platelet aggregation.(3-4) Bleeding has been reported with the use of ibrutinib,(1-4) anticoagulants, or antiplatelets alone.

CLINICAL EFFECTS: Concurrent use of ibrutinib with either anticoagulants or antiplatelets may increase the risk of hemorrhage.

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs).

PATIENT MANAGEMENT: The Canadian product monograph for ibrutinib recommends concurrent use with anticoagulants or antiplatelets should be approached with caution. If therapeutic anticoagulation is required, consider temporarily withholding ibrutinib therapy until stable anticoagulation in achieved.(2) The US prescribing information for ibrutinib states patients receiving concurrent therapy with ibrutinib and anticoagulants and/or antiplatelets should be closely monitored for changes in platelet count or in International Normalized Ratio (INR). Carefully weigh the risks vs. benefits of concurrent therapy in patients with significant thrombocytopenia. If a bleeding event occurs, follow manufacturer instructions for ibrutinib dose adjustment.(1) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory tests (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug.

DISCUSSION: Bleeding has been reported with ibrutinib alone.(1-3) Across 27 clinical trials, grade 3 or higher bleeding events, e.g. subdural hematoma, gastrointestinal bleeding or hematuria, have occurred in up to 4% of patients, with 0.4% fatality. Grade 3 or 4 thrombocytopenia occurred in 5-19% of patients. Bleeding events of any grade occurred in 39% of patients treated with ibrutinib.(1) Concurrent use of anticoagulants or antiplatelets has been reported to increase the risk for major bleeding. In clinical trials, major bleeding occurred in 3.1% of patients taking ibrutinib without concurrent anticoagulants or antiplatelets, 4.4% of patients on concurrent antiplatelets with or without anticoagulants, and 6.1% of patients on concurrent anticoagulants with or without antiplatelets.(1) In an open-label, phase 2 trial of patients with relapsed/refractory mantle cell lymphoma on ibrutinib, 61 patients (55%) on concurrent anticoagulants or antiplatelets had a higher rate of bleeding (69% any grade, 8% grade 3-4) than patients not on anticoagulants or antiplatelets (28% any grade, 4% grade 3-4).(5) A retrospective trial found a hazard ratio of 20 (95% CI, 2.1-200) for patients on ibrutinib with concurrent anticoagulants and antiplatelets. There was a trend towards an increased bleeding risk in patients on either anticoagulants or antiplatelets, but this was not statistically significant on multivariate analysis.(6) A case report of 2 patients with chronic lymphocytic leukemia (CLL) on ibrutinib and dabigatran demonstrated no stroke nor bleeding events during the mean 11.5 month follow-up.(7) A case report of 4 patients with lymphoproliferative disease on concurrent dabigatran and ibrutinib demonstrated no stroke nor major bleeding events. 1 patient experienced grade 2 conjunctival hemorrhage whilst on both ibrutinib and dabigatran. The anticoagulant was withheld and successfully re-initiated at a lower dose with no further bleeding events.(8)

Selected Antihypertensive Agents/Selected Maois

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Both MAOIs and antihypertensive agents may increase the risk of postural hypotension.(1,2)

CLINICAL EFFECTS: Postural hypotension may occur with concurrent therapy of MAOIs and antihypertensive agents.(1,2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturer of phenelzine states all patients should be followed closely for symptoms of postural hypotension. Hypotensive side effects have occurred in patients who have been hypertensive and normotensive, as well as hypotensive at initiation of phenelzine.(1) The manufacturer of tranylcypromine states hypotension has been observed most commonly but not exclusively in patients with pre-existing hypertension. Tranylcypromine doses greater than 30 mg daily have a major side effect of postural hypotension and can lead to syncope. Gradual dose titration is recommended to decrease risk of postural hypotension. Combined use with other agents known to cause hypotension have shown to have additive side effects and should be monitored closely.(2) Monitor the patient for signs and symptoms of postural hypotension including dizziness, lightheadedness, or weakness, especially upon standing. Monitor blood pressure as well as orthostatic vitals and adjust antihypertensive therapy, including decreasing the dose, dividing doses, or scheduling doses at bedtime, as needed to maintain goal blood pressure. If blood pressure remains hypotensive, consider decreasing the dose of phenelzine or tranylcypromine. In some cases, discontinuation of one or both agents may be necessary.(3) Normotensive patients on stable antihypertensive therapy who are started on either phenelzine or tranylcypromine may be at increased risk for hypotension. Hypertensive patients on stable phenelzine or tranylcypromine who require antihypertensive therapy would be at decreased risk for hypotension.

DISCUSSION: A review article describes the pharmacology of phenelzine and tranylcypromine as non-selective MAOIs which inhibit both type A and type B substrates. Orthostatic hypotension is described as the most common MAOI side effect and usually occurs between initiation and the first 3-4 weeks of therapy.(3) In a double-blind study, 71 patients were randomized to receive a 4-week trial of either tranylcypromine, amitriptyline, or the combination. The number of patients reporting dizziness at 4 weeks was not different between the three treatment groups (tranylcypromine 52.4%; amitriptyline 65%; combination 66.7%). Blood pressure (BP) assessment noted a significant drop in standing BP in the tranylcypromine group compared to baseline (systolic BP change = -10 mmHg; p<0.02 and diastolic BP change = -9 mmHg; p<0.02). Combination therapy also had a significant drop in standing BP compared to baseline (systolic BP change = -9 mmHg; p<0.02). Patients receiving amitriptyline had no significant change in BP from baseline at 4 weeks. All three groups had a trend toward increasing orthostatic hypotension in BP changes from lying to standing. The change in orthostatic hypotension was significant in the amitriptyline group with an average systolic BP orthostatic drop of -9 mmHg (p<0.05).(4) A randomized, double-blind study of 16 inpatients with major depressive disorder were treated with either phenelzine or tranylcypromine. Cardiovascular assessments were completed at baseline and after 6 weeks of treatment. After 6 weeks, 5/7 patients (71%) who received phenelzine had a decrease in standing systolic BP greater than 20 mmHg from baseline. Head-up tilt systolic and diastolic BP decreased from baseline in patients on phenelzine (98/61 mmHg v. 127/65 mmHg, respectively; systolic change p=0.02 and diastolic change p=0.02). After 6 weeks, 6/9 patients (67%) who received tranylcypromine had a decrease in standing systolic BP greater than 20 mmHg from baseline. Head-up tilt systolic and diastolic BP decreased from baseline in patients on tranylcypromine (113/71 mmHg v. 133/69 mmHg, respectively; systolic change p=0.09 and diastolic change p=0.07).(5) Selected MAOIs linked to this monograph include: phenelzine and tranylcypromine. Selected antihypertensive agents include: ACE inhibitors, alpha blockers, ARBs, beta blockers, calcium channel blockers, aprocitentan, clonidine, hydralazine, moxonidine, and sparsentan.

Selected Antihypertensives And Vasodilators/Apomorphine

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Apomorphine causes dose-dependent decreases in blood pressure. Concurrent use with antihypertensive agents may result in additive effects on blood pressure.(1)

CLINICAL EFFECTS: Concurrent use of antihypertensives and apomorphine may result in orthostatic hypotension with or without dizziness, nausea, or syncope.(1)

PREDISPOSING FACTORS: The risk of orthostatic hypotension may be increased during dose escalation of apomorphine and in patients with renal or hepatic impairment.(1)

PATIENT MANAGEMENT: Patients receiving concurrent therapy should be monitored for hypotension. Counsel patients about the risk of orthostatic hypotension.(1)

DISCUSSION: Healthy volunteers who took sublingual nitroglycerin (0.4 mg) concomitantly with apomorphine experienced a mean largest decrease in supine systolic blood pressure (SBP) of 9.7 mm Hg and in supine diastolic blood pressure (DBP) of 9.3 mm Hg, and a mean largest decrease in standing SBP and DBP of 14.3 mm Hg and 13.5 mm Hg, respectively. The maximum decrease in SBP and DBP was 65 mm Hg and 43 mm Hg, respectively. When apomorphine was taken alone, the mean largest decrease in supine SBP and DBP was 6.1 mm Hg and 7.3 mm Hg, respectively, and in standing SBP and DBP was 6.7 mm Hg and 8.4 mm Hg, respectively.(1)

Selected Nephrotoxic Agents/Adefovir

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Recommended doses of adefovir have been associated with delayed nephrotoxicity.(1-4) Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1)

CLINICAL EFFECTS: Concurrent use of adefovir with nephrotoxic agents such as intravenous aminoglycosides, amphotericin B, cyclosporine, tacrolimus,tenofovir, vancomycin, voclosporin and non-steroidal anti-inflammatory agents may result in renal toxicity.(1) Other nephrotoxic agents include capreomycin, cisplatin, gallium nitrate, high-dose methotrexate, intravenous pentamidine, and streptozocin.

PREDISPOSING FACTORS: Patients with pre-existing renal impairment(1,2) or receiving multiple nephrotoxic agents appear to be at greater risk for nephrotoxicity.

PATIENT MANAGEMENT: Evaluate renal function prior to initiation of concurrent therapy and continue renal function monitoring during therapy. Dose adjustments may be required for impaired renal function. Weigh the risks and benefits of concurrent therapy in patients with treatment-emergent nephrotoxicity.

DISCUSSION: Because of the known risks for adefovir nephrotoxicity, particularly at higher than recommended doses, the safety of adefovir has not been studied in patients receiving other known potentially nephrotoxic agents.

Selected Nephrotoxic Agents/Cisplatin

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The nephrotoxic effects of aminoglycosides or non-steroidal anti-inflammatory drugs (NSAIDs) may be additive to those of cisplatin.

CLINICAL EFFECTS: The concurrent administration of amikacin, gentamicin, tobramycin, or NSAIDs with cisplatin may result in additive nephrotoxic effects.(1,2,5,6)

PREDISPOSING FACTORS: Pre-existing renal insufficiency, advanced age, dehydration may increase the risk of nephrotoxicity.(1,5,6)

PATIENT MANAGEMENT: The US labeling for aminoglycosides and cisplatin states that the concurrent use of aminoglycosides and cisplatin should be avoided.(1,3,4,6) Inform patients that concurrent cisplatin and aminoglycosides or NSAIDs can cause nephrotoxicity and that renal function and electrolyte monitoring during treatment is necessary.(2)

DISCUSSION: The US manufacturers of amikacin, gentamicin and tobramycin state that since the nephrotoxic effects of these medications may be additive, avoid concurrent or sequential use of other neurotoxic and/or nephrotoxic agents including cisplatin.(1,3,6)

Selected Nephrotoxic Agents/Immune Globulin Iv (Igiv)

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Immune Globulin Intravenous (IGIV) products, particularly those containing sucrose, can cause renal dysfunction, acute renal failure, osmotic nephrosis, and/or death. Concurrent administration of other nephrotoxic agents may result in additive or synergistic effects on renal function.(1-4)

CLINICAL EFFECTS: Concurrent use of Immune Globulin Intravenous (IGIV) products with nephrotoxic agents such as adefovir, intravenous aminoglycosides, amphotericin B, non-steroidal anti-inflammatory agents, tenofovir, and vancomycin may result in renal toxicity.(1-4) Other nephrotoxic agents include capreomycin, gallium nitrate, and streptozocin.

PREDISPOSING FACTORS: Patients at risk of acute renal failure include those with any degree of pre-existing renal insufficiency, diabetes mellitus, advanced age (above 65 years of age), volume depletion, sepsis, paraproteinemia, or receiving known nephrotoxic drugs.(1-4) Renal dysfunction and acute renal failure occur more commonly in patients receiving IGIV products containing sucrose.(3-4)

PATIENT MANAGEMENT: For patients at risk of renal dysfunction or renal failure, the US manufacturers of Immune Globulin Intravenous (IGIV) products recommends administration at the minimum dose and infusion rate practicable; ensure adequate hydration in patients before administration; and monitor renal function and urine output with assessment of blood urea nitrogen (BUN) and serum creatinine before initial infusion and at regular intervals during therapy.(1-3) Concurrent administration of potentially nephrotoxic agents should be avoided.(1) Review prescribing information for IGIV product to be administered for sucrose content. If concurrent therapy is warranted, monitor renal function closely. In high risk patients, consider selecting an IGIV product that does not contain sucrose.

DISCUSSION: The safety of Immune Globulin Intravenous (IGIV) has not been studied in patients receiving other known potentially nephrotoxic agents. Renal impairment is a major toxicity of IGIV products.(1-3) A review of the FDA renal adverse events (RAEs) (i.e. acute renal failure or insufficiency) from June 1985 to November 1998 identified 120 reports worldwide associated with IGIV administration. In the US, the FDA received 88 reports of cases with clinical and/or laboratory findings consistent with RAE (i.e. increased serum creatinine, oliguria, and acute renal failure). Patient cases involved a median age of 60.5 years and 55% were male. Of the 54 patients who developed acute renal failure, 65% were greater than 65 years, 56% had diabetes, and 26% had prior renal insufficiency; 59% had one, 35% had two, and 6% had three of these conditions. Upon review of the IGIV product received, 90% of cases received sucrose-containing IGIV products with the remaining patients receiving either maltose- or glucose-containing products. Approximately 40% of affected patients required dialysis and RAE may have contributed to death in 15% of patients.(4)

Selected Nephrotoxic Agents/Tenofovir

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Tenofovir and other nephrotoxic agents may result in additive or synergistic effects on renal function and increase nephrotoxicity risk.(1)

CLINICAL EFFECTS: Concurrent use of tenofovir and other nephrotoxic agents may result in renal toxicity and acute renal failure.(1) Reports of acute renal failure and Fanconi syndrome have been reported with tenofovir use.(2,3) However, this has been reported in 3 case reports and the renal failure may have been complicated by other pre-existing conditions.(2)

PREDISPOSING FACTORS: Pre-existing renal dysfunction, long duration of use, low body weight, concomitant use of drugs that may increase tenofovir levels may increase the risk of nephrotoxicity.(1)

PATIENT MANAGEMENT: The US prescribing information for tenofovir recommends avoiding concurrent or recent use of a nephrotoxic agent.(3) Evaluate renal function prior to initiation of concurrent therapy and continue renal function monitoring during therapy. Dose adjustments may be required for impaired renal function. Tenofovir should be avoided with high-dose or multiple NSAIDs. Alternatives to NSAIDs should be considered in patients at risk for renal dysfunction.(3) Patients receiving concurrent NSAIDs with tenofovir should be monitored for possible renal toxicity.(1,2) The dosing interval should be adjusted in patients with a baseline creatinine clearance of less than 50 ml/min.(1-3)

DISCUSSION: From March 18, 2003 to December 1, 2005, Health Canada received 10 reports of nephrotoxic reactions with tenofovir. Three of these occurred following the addition of a NSAID to tenofovir therapy. In the first report, a patient maintained on tenofovir for 29 months developed acute renal failure and acute tubular necrosis requiring dialysis 5 days after beginning indomethacin (100 mg rectally twice daily). In the second report, a patient maintained on tenofovir for 7 months developed acute renal failure and acute tubular necrosis after taking 90 tablets of naproxen (375 mg) over 2 months. The patient died. In the third report, a patient maintained on tenofovir for over a year developed acute renal failure and nephrotic syndrome after 2 months of valdecoxib (20 mg daily) therapy. Symptoms subsided following discontinuation of valdecoxib.(1)

Selected Nsaids; Aspirin/Ssris; Snris

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: Serotonin release by platelets plays a role in hemostasis.(1,2) The increased risk of bleeding may be a result of a decrease in serotonin reuptake by platelets.

CLINICAL EFFECTS: Concurrent use of a selective serotonin reuptake inhibitor(1-7,13) or a serotonin-norepinephrine reuptake inhibitor(8-10) and a NSAID may result in bleeding.

PREDISPOSING FACTORS: The risk for bleeding episodes may be greater in patients with multiple disease-associated factors (e.g. thrombocytopenia, advanced liver disease). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g., anticoagulants, antiplatelets, or corticosteroids. Risk of GI bleed may be increased in patients who are of older age, in poor health status, or who use alcohol or smoke. Risk may also be increased with longer duration of NSAID use and prior history of peptic ulcer disease and/or GI bleeding. Renal impairment has been associated with an elevated risk of GI bleed in patients on SSRIs.(15)

PATIENT MANAGEMENT: Selective serotonin reuptake inhibitors(1-7,13) or serotonin-norepinephrine reuptake inhibitors(8-10) and NSAIDs should be used concurrently with caution. Patients should be warned about the increased risk of bleeding and be educated about signs and symptoms of bleeding.(1-11,13) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Discontinue anti-platelet agents in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling.

DISCUSSION: In a retrospective review of 5 years of data from the Pharmaco-Epidemiologic Prescription Database, hospitalizations for upper gastro-intestinal bleeding in antidepressant users were compared to those in non-antidepressant users. The risk of a bleed in a patient using an NSAID only based on an observed-expected ratio was 4.5 and in a patient using low-dose aspirin only was 2.5. Concurrent use of a selective serotonin reuptake inhibitor with NSAIDs or low-dose aspirin increased the risk of bleeding to 12.2 and 5.2, respectively.(11) In another study, there were 16 cases of upper gastrointestinal bleeding in patients receiving concurrent therapy with selective serotonin reuptake inhibitors and NSAIDs. Adjusted relative risk of bleeding with NSAIDs, selective serotonin reuptake inhibitors, or both were 3.7, 2.6, or 15.6, respectively.(12)

Selected Nsaids; Salicylates/Ace Inhibitors

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: NSAIDs inhibit prostaglandin synthesis which can lead to afferent arteriolar vasoconstriction and decreased renal blood flow. ACE inhibitors can cause vasodilation of the efferent renal arteriole which may result in decreased glomerular filtration rate.

CLINICAL EFFECTS: Concurrent use of ACE inhibitors with NSAIDs may result in decreased antihypertensive effects. In patients with existing renal impairment, the use of these agents together may also result in further deterioration of renal clearance caused by renal hypoperfusion. Concurrent use of ACE inhibitors with NSAIDs and diuretics may result in increased risk of acute kidney injury (AKI).

PREDISPOSING FACTORS: Low water intake/dehydration, drug sensitivity, greater than 75 years of age, and renal impairment may increase an individuals susceptibility to AKI.

PATIENT MANAGEMENT: Patients maintained on ACE inhibitors should be monitored for a loss of blood pressure control and a change in renal function if an NSAID is added to their regimen. Patients receiving concurrent therapy may require higher doses of ACE inhibitors. If blood pressure control cannot be achieved or if the patient's renal function deteriorates, the NSAID may need to be discontinued. Patients should be monitored for hypotension if NSAIDs are withdrawn from concurrent ACE inhibitor therapy. Concurrent use of ACE inhibitors with NSAIDs and diuretics should be used with caution and monitored closely for signs of AKI.

DISCUSSION: In a computational study, the risk of AKI using triple therapy (combination of a diuretic, renin-angiotensin system (RAS) inhibitor, and NSAID) was assessed. The study found the following factors may increase an individual's susceptibility to AKI: low water intake, drug sensitivity, greater than 75 years of age, and renal impairment.(30,31) In an observational study, current use of a triple therapy combination was associated with an increased rate of acute kidney injury (rate ratio (RR) 1.31, 95% confidence interval (CI) 1.12-1.53). The highest risk of AKI associated with triple therapy were observed in the first 30 days of use (RR 1.82, CI 1.35-2.46).(32) Indomethacin has been shown to inhibit the antihypertensive effect of captopril, cilazapril, enalapril, losartan, perindopril, and valsartan. Ibuprofen has been shown to decrease the antihypertensive effects of captopril. Two separate case reports describe individuals suspected of ACEI-associated angioedema precipitated by NSAIDs. Both cases reported symptom resolution after cessation of the NSAID. Studies have shown that sulindac does not affect the antihypertensive effects of captopril and enalapril. One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology.

Selected Nsaids; Salicylates/Triamterene; Amiloride

SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed.

MECHANISM OF ACTION: The exact mechanism is unknown; however, nonsteroidal anti-inflammatory (NSAID) inhibition of prostaglandins may allow triamterene or amiloride- induced nephrotoxicity or hyperkalemia to occur in some patients.

CLINICAL EFFECTS: Possible renal failure or hyperkalemia.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: When possible, avoid concurrent therapy with triamterene or amiloride with NSAIDs. If these agents are used concurrently, monitor renal function and serum electrolytes. If decreased renal function or hyperkalemia develops, discontinue both agents.

DISCUSSION: Although acute renal failure and hyperkalemia have only been reported in studies and case reports involving indomethacin, diclofenac, flurbiprofen, and ibuprofen with either triamterene or amiloride, the proposed mechanism suggests that all nonsteroidal anti-inflammatory agents may be capable of this interaction. Patients receiving diuretics are at an increased risk of NSAID-induced renal failure.

Known hypersensitivity to ropivacaine hydrochloride or other local anesthetics of the amide type.

*Clonidine is contraindicated in patients with known hypersensitivity to the drug or to any ingredient or component in the formulation.

*Administration of epidural clonidine is contraindicated in patients receiving anticoagulant therapy, in those with a bleeding diathesis, and in the presence of an injection site infection.

*Administration of epidural clonidine above the C4 dermatome is contraindicated because of inadequate safety data supporting such use.

*Administration of epidural clonidine also is not recommended in most patients with severe cardiovascular disease or in patients who are hemodynamically unstable.

• Aspirin exacerbated respiratory disease
• Cerebrovascular accident
• Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• History of roux-en-Y gastric bypass
• Hypovolemia
• Methemoglobinemia
• Post-operative from CABG surgery
• Pregnancy
• Renal transplant

• Acute myocardial infarction
• Atrial fibrillation
• Atrioventricular block
• Bradycardia
• Butyrylcholinesterase deficiency
• Chronic heart failure
• Chronic kidney disease stage 3A (moderate) GFR 45-59 ml/min
• Chronic kidney disease stage 3B (moderate) GFR 30-44 ml/min
• Gastrointestinal perforation
• Gastrointestinal ulcer
• Glucose-6-phosphate dehydrogenase (g6Pd) deficiency
• Hemolytic anemia from pyruvate kinase and g6PD deficiencies
• Hemorrhage
• History of kidney donation
• Hypotension
• Increased risk of bleeding
• Invasive surgical procedure
• Myasthenia gravis
• Nephrectomy
• Postsurgical hemorrhage
• Sinus bradycardia
• Structural disorder of heart
• Systemic mastocytosis
• Thrombotic disorder
• Tobacco smoker

• Acute myocardial infarction
• Anemia
• Asthma
• Cerebrovascular disorder
• Chronic kidney disease stage 5 (failure) GFr<15 ml/min
• Chronic myocardial ischemia
• Disease of liver
• Dry eye
• Hypertension
• Hypotension
• Inflammatory bowel disease
• Kidney disease with likely reduction in glomerular filtration rate (GFr)
• Kidney disease with reduction in glomerular filtration rate (GFr)
• Systemic lupus erythematosus

Adverse effects reported in 5% or more of patients receiving ropivacaine hydrochloride in clinical studies include hypotension, nausea, vomiting, bradycardia, fever, pain, postoperative complications, anemia, paresthesia, headache, pruritus, and back pain.

Most adverse effects with clonidine are mild in nature and tend to decrease with continuation of therapy. The most common, dose-related adverse effects include dry mouth, drowsiness, dizziness, constipation, and sedation.

Adverse effects with transdermal clonidine are generally similar to those with oral therapy. The most frequent adverse effects with transdermal clonidine were dry mouth, drowsiness, and local adverse dermatologic effects.

The most frequent adverse effects occurring with clonidine hydrochloride epidural infusion for severe intractable cancer pain were hypotension, postural hypotension, dizziness, anxiety, and dry mouth; asymptomatic bradycardia was also observed in 1 patient. Mean heart rate and blood pressure reductions were also observed in patients receiving clonidine hydrochloride epidural infusion. Upon withdrawal of clonidine, 4 patients also experienced rebound hypertension, of which 1 suffered a cerebrovascular accident.

Adverse effects occurring in >=5% of patients receiving clonidine as monotherapy for ADHD include somnolence, fatigue, irritability, nightmares, insomnia, constipation, and dry mouth. When used as adjunctive therapy to stimulants in ADHD, adverse effects reported in >=5% of patients include somnolence, fatigue, decreased appetite, and dizziness.

More Frequent

• Bradycardia
• Edema
• Hypotension

Less Frequent

• Allergic dermatitis
• Depression
• Hypertension
• Hypertension
• Hypokalemia
• Skin rash
• Stomatitis

Rare or Very Rare

• Abnormal ECG
• Anaphylaxis
• Anemia
• Angioedema
• Asthma
• Atrial fibrillation
• Atrioventricular block
• Azotemia
• Bleeding from wound
• Bloody stools
• Blurred vision
• Bradycardia
• Bronchospastic pulmonary disease
• Chronic heart failure
• CNS toxicity
• Depression
• DRESS syndrome
• Dyspnea
• Eosinophilia
• Epistaxis
• Erythema multiforme
• Exfoliative dermatitis
• Extrapyramidal disease
• Extrasystoles
• Flank pain
• Gastritis
• Gastrointestinal hemorrhage
• Gastrointestinal perforation
• Gastrointestinal ulcer
• Hallucinations
• Hearing loss
• Hematuria
• Hepatitis
• Hepatitis
• Hyperkalemia
• Hyperkinesis
• Hypersensitivity drug reaction
• Hypomagnesemia
• Hypotension
• Infection
• Jaundice
• Jaundice
• Laryngeal edema
• Nephritis
• Nightmares
• Oliguria
• Pancreatitis
• Peptic ulcer
• Platelet aggregation inhibition
• Proteinuria
• Pulmonary edema
• Purpura
• Raynaud's phenomenon
• Rectal bleeding
• Renal failure
• Seizure disorder
• Seizure disorder
• Stevens-johnson syndrome
• Syncope
• Thrombocytopenic disorder
• Thromboembolic disorder
• Tongue swelling
• Tonic clonic seizure
• Toxic epidermal necrolysis
• Unconsciousness
• Urinary retention
• Ventricular arrhythmias

More Frequent

• Abdominal pain with cramps
• Anemia
• Back pain
• Constipation
• Diarrhea
• Dizziness
• Dizziness
• Drowsy
• Drowsy
• Dyspepsia
• Fatigue
• Fever
• General weakness
• Headache disorder
• Headache disorder
• Injection site sequelae
• Irritability
• Nausea
• Nausea
• Pain
• Paresthesia
• Pruritus of skin
• Xerostomia

Less Frequent

• Abnormal sexual function
• Acute abdominal pain
• Anorexia
• Body fluid retention
• Chest pain
• Chills
• Constipation
• Cramps
• Dizziness
• Dry eye
• Dyspnea
• Earache
• Erectile dysfunction
• Hyperhidrosis
• Hypoesthesia
• Increased appetite
• Nasal congestion
• Nausea
• Nervousness
• Ocular irritation
• Ocular itching
• Oliguria
• Orthostatic hypotension
• Pruritus of skin
• Rhinitis
• Sore throat
• Symptoms of anxiety
• Tachycardia
• Tremor
• Upper abdominal pain
• Urinary retention
• Urinary tract infection
• Vomiting
• Vomiting
• Vomiting

Rare or Very Rare

• Accommodation disorder
• Acquired horner syndrome
• Acute bronchospasm
• Acute cognitive impairment
• Agitation
• Agitation
• Anorexia
• Anticholinergic toxicity
• Blepharoptosis
• Blurred vision
• Blurred vision
• Cough
• Cough
• Cramps in legs
• Delirium
• Delusional disorder
• Drowsy
• Dry nose
• Dysgeusia
• Dysgeusia
• Dyskinesia
• Epigastric fullness
• Eructation
• Euphoria
• Fecal incontinence
• Fever
• Fever
• Flatulence
• General weakness
• General weakness
• Gynecomastia
• Hallucinations
• Hallucinations
• Headache disorder
• Hearing loss
• Hematoma
• Hypokinesia
• Hypothermia
• Hypotonia
• Increased urinary frequency
• Injection site sequelae
• Insomnia
• Insomnia
• Malaise
• Malaise
• Memory impairment
• Mood changes
• Muscle fasciculation
• Myalgia
• Myalgia
• Nervousness
• Nervousness
• Nightmares
• Nightmares
• Nocturia
• Oral hypoesthesia
• Orthostatic hypotension
• Pallor
• Pallor
• Palpitations
• Paresthesia
• Paresthesia
• Peripheral sensory neuropathy
• Phlebitis
• Polydipsia
• Polyuria
• Rhinitis
• Skin photosensitivity
• Skin rash
• Sleep disorder
• Slurred speech
• Stupor
• Stupor
• Symptoms of anxiety
• Syncope
• Syncope
• Tenesmus
• Tinnitus
• Tinnitus
• Tremor
• Tremor
• Urinary retention
• Urticaria
• Urticaria
• Vertigo
• Vertigo
• Visual changes
• Weight gain
• Weight gain
• Xerostomia

No enhanced messaging available.

The manufacturer states that efficacy and safety of ropivacaine have not been established in pediatric patients; however, the drug has been used in children for postoperative analgesia.

The safety and efficacy of extended-release clonidine tablets and extended-release oral suspension (Onyda(TM) XR) for the treatment of ADHD have been established in pediatric patients 6-17 years of age. Use for this indication is based on evidence from 3 adequate, well-controlled studies, a short-term, placebo-controlled monotherapy study, a short-term, adjunctive therapy study, and a long-term randomized monotherapy study.

Safety and efficacy of oral clonidine hydrochloride, extended-release clonidine (Nexiclon(TM) XR), and clonidine transdermal system for the management of hypertension in children have not been established.

The safety and efficacy of clonidine hydrochloride epidural infusion have been established in pediatric patients who are old enough to tolerate placement and management of an epidural catheter, based on evidence from adequate, well-controlled studies in adults and experience with the use of clonidine in pediatric patients for other indications. Epidural clonidine should be used only in pediatric patients with severe, intractable cancer pain that is unresponsive to epidural or spinal opiates and to other conventional analgesic therapy.

Children may be more likely to experience CNS depression associated with clonidine overdosage than adults. In children, signs of toxicity have occurred with clonidine doses as low as 0.1 mg. Rare cases of clonidine toxicity (many involving children) associated with accidental or deliberate mouthing or ingestion of clonidine transdermal systems have been reported.

The manufacturer of oral clonidine states that because children frequently experience vomiting associated with GI illnesses, they may be particularly susceptible to hypertensive episodes resulting from sudden inability to ingest the drug.

Category B.

There are no adequate and well-controlled studies of ropivacaine in pregnant women. Animal reproductive studies have not shown any evidence of teratogenicity or adverse developmental effects; however, maternal toxicity has been observed. Local anesthetics rapidly cross the placenta during epidural administration and can cause varying degrees of maternal, fetal, and neonatal toxicity. Ropivacaine should be used during pregnancy only if the benefits outweigh the risks.

Maternal hypotension has occurred with the use of ropivacaine for obstetrical pain relief. (See Cautions in the Local Anesthetics, Parenteral, General Statement 72:00.)

Reproduction studies in rabbits using oral clonidine hydrochloride dosages up to about 3 times the maximum recommended human dosage have not revealed evidence of teratogenicity or embryotoxicity. However, in female rats receiving the drug continuously for 2 months prior to mating, an increased incidence of fetal resorptions occurred with oral dosages as low as one-third the maximum recommended human dosage (1/15th the maximum recommended human dosage on a mg/m2 basis); resorptions were not increased when these or higher dosages (up to 3 times the maximum recommended human dosage) were administered during days 6-15 of gestation. An increased incidence of fetal resorptions was observed when much higher dosages (40 times the maximum recommended human dosage on a mg/kg basis and 4-8 times the maximum recommended human dosage on a mg/m2 basis) were administered to mice and rats during days 1-14 of gestation; the lowest dosage used in the study was 0.5 mg/kg. There are no adequate and controlled studies to date using clonidine in pregnant women, and the drug should be used during pregnancy only when clearly needed.

There is a pregnancy exposure registry available that monitors pregnancy outcomes in women exposed to ADHD medications, including clonidine, during pregnancy. Patients can register by calling the National Pregnancy Registry for Psychiatric Medications at 1-866-961-2388 or by visiting https://womensmentalhealth.org/research/pregnancyregistry/adhd-medications/ .

Use of NSAIAs during pregnancy at about 30 weeks of gestation or later can cause premature closure of the fetal ductus arteriosus, and use at about 20 weeks of gestation or later has been associated with fetal renal dysfunction resulting in oligohydramnios and, in some cases, neonatal renal impairment. Because of these risks, use of NSAIAs should be avoided in pregnant women at about 30 weeks of gestation or later; if NSAIA therapy is necessary between about 20 and 30 weeks of gestation, the lowest effective dosage and shortest possible duration of treatment should be used. Monitoring of amniotic fluid volume via ultrasound examination should be considered if the duration of NSAIA treatment exceeds 48 hours; if oligohydramnios occurs, the drug should be discontinued and follow-up instituted according to clinical practice. Pregnant women should be advised to avoid use of NSAIAs beginning at 20 weeks' gestation unless otherwise advised by a clinician; they should be informed that NSAIAs should be avoided beginning at 30 weeks' gestation because of the risk of premature closure of the fetal ductus arteriosus and that monitoring for oligohydramnios may be necessary if NSAIA therapy is required for longer than 48 hours' duration between about 20 and 30 weeks of gestation.

Known effects of NSAIAs on the human fetus during the third trimester of pregnancy include prenatal constriction of the ductus arteriosus, tricuspid incompetence, and pulmonary hypertension; nonclosure of the ductus arteriosus during the postnatal period (which may be resistant to medical management); and myocardial degenerative changes, platelet dysfunction with resultant bleeding, intracranial bleeding, renal dysfunction or renal failure, renal injury or dysgenesis potentially resulting in prolonged or permanent renal failure, oligohydramnios, GI bleeding or perforation, and increased risk of necrotizing enterocolitis.

Fetal renal dysfunction resulting in oligohydramnios and, in some cases, neonatal renal impairment has been observed, on average, following days to weeks of maternal NSAIA use, although oligohydramnios has been observed infrequently as early as 48 hours after initiation of NSAIA therapy. Oligohydramnios is often, but not always, reversible (generally within 3-6 days) following discontinuance of NSAIA therapy. Complications of prolonged oligohydramnios may include limb contracture and delayed lung maturation. A limited number of case reports have described maternal NSAIA use and neonatal renal dysfunction, in some cases irreversible, without oligohydramnios. Some cases of neonatal renal dysfunction have required treatment with invasive procedures such as exchange transfusion or dialysis. Deaths associated with neonatal renal failure have been reported. Methodologic limitations of these postmarketing studies and case reports include lack of a control group; limited information regarding dosage, duration, and timing of drug exposure; and concomitant use of other drugs. These limitations preclude establishing a reliable estimate of the risk of adverse fetal and neonatal outcomes with maternal NSAIA use. Available data on neonatal outcomes generally involved preterm infants, and the extent to which certain reported risks can be generalized to full-term infants is uncertain.

Animal data indicate that prostaglandins have an important role in endometrial vascular permeability, blastocyst implantation, and decidualization. In animal studies, inhibitors of prostaglandin synthesis, such as ketorolac, were associated with increased pre- and post-implantation losses. Prostaglandins also have an important role in fetal kidney development. In animal studies, inhibitors of prostaglandin synthesis impaired kidney development at clinically relevant doses.

Reproduction studies in rabbits and rats receiving oral ketorolac tromethamine dosages of 3.6 and 10 mg/kg daily, respectively (about 1.8 and 5 times the maximum recommended human parenteral dosage, respectively), during the period of organogenesis have not revealed evidence of harm to the fetus; however, oral dosages exceeding the maximum recommended human parenteral dosage in rats produced delayed parturition and dystocia, probably secondary to inhibition of prostaglandin synthesis.

Use of ketorolac during labor and delivery is contraindicated, since its inhibitory effect on prostaglandin synthesis may adversely affect fetal circulation and inhibit uterine contractions, thus increasing the risk of uterine hemorrhage. In animal studies, NSAIAs, including ketorolac, delayed parturition and increased the incidence of stillbirths.

Ropivacaine is distributed into milk in rats; it is not known whether the drug or its metabolites are distributed into human milk. Based on the milk to plasma concentration ratio and estimated exposures in rats, infant exposure to ropivacaine from breastfeeding is expected to be far less than the exposure in utero. Ropivacaine should be used with caution in nursing women.

Since clonidine is distributed into milk, the drug should be used with caution in nursing women. The drug is excreted into milk at relative infant doses ranging from 4.1-8.4% of the maternal weight-adjusted dosage. Although in most cases, there were no reported adverse effects in breast-fed infants exposed to clonidine, one infant developed sedation, hypotonia, and apnea after clonidine exposure through breast milk. Monitor infants exposed to clonidine through breast milk for symptoms of hypotension and bradycardia, such as sedation, lethargy, tachypnea and poor feeding. Consider the developmental and health benefits of breast-feeding along with the mother's clinical need for the drug and any potential adverse effects on the breast-fed infant from exposure to clonidine or the underlying maternal condition.

Ketorolac may be distributed into milk in small amounts. (See Distribution under Pharmacokinetics.) The developmental and health benefits of breast-feeding should be considered along with the mother's clinical need for ketorolac and any potential adverse effects on the breast-fed infant from the drug or from the underlying maternal condition.

Caution should be exercised when ketorolac is used in nursing women; although available information has not revealed any specific adverse events in nursing infants, women who are breast-feeding should be advised to contact their infant's clinician if they observe any adverse events.

When conventional clonidine tablets are used for hypertension, the manufacturer states that geriatric patients may benefit from a lower initial dosage of 0.05 mg twice daily. Geriatric patients with hypertension may also benefit from an initial lower dosage when extended-release clonidine tablets (Nexiclon(R) XR) are used.

In clinical studies of ropivacaine, 27% of patients receiving the drug were 65 years of age or older and 4% were 75 years of age or older. The drug was found to be safe and effective in these patients.

Differences in various pharmacodynamic measures of ropivacaine have been observed with increasing age. In one clinical study, the upper level of analgesia increased with age, the maximum decrease of mean arterial pressure declined with age for the first hour following epidural administration, and the intensity of motor blockade increased with age.

Because ropivacaine and its metabolites are substantially excreted by the kidneys, the risk of toxic reactions to the drug may be greater in patients with renal impairment. Dosage should therefore be selected with caution in geriatric patients, usually starting at the lower end of the dosage range, since such patients are more likely to have decreased hepatic, renal, and/or cardiac function as well as concomitant illnesses. The manufacturer states that it may be useful to monitor renal function in geriatric patients.

Geriatric patients may benefit from lower initial dosages of clonidine.