Isoproterenol Hcl (isoproterenol HCl)

Dosage of isoproterenol hydrochloride is expressed in terms of the salt.

Isoproterenol should be initiated at the lowest recommended dose and increased gradually based on patient response. Adjust dosage according to clinical and hemodynamic parameters including heart rate, central venous pressure, systemic blood pressure, and urine output.

Isoproterenol hydrochloride injection is available in single-dose vials containing 0.2 mg/mL of the drug. Isoproterenol hydrochloride usually is administered by direct (''bolus'') IV injection or IV infusion. The drug may also be administered by IM, subcutaneous, or intracardiac injection.

For IM, subcutaneous, or intracardiac injection, commercially available isoproterenol hydrochloride injection is administered undiluted. For IV administration, the drug should be diluted prior to administration.

Isoproterenol should be stored at 20-25degreesC. Protect from light, and keep in an opaque container until use.

Isoproterenol should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. The injection should be discarded if the solution is pinkish or darker than slightly yellow or contains a precipitate. Unused portions should be discarded.

No dosing information is available for this tab.

No dosing information is available for this tab.

There is no enhanced messaging for this drug.

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

Sympathomimetics/Dihydroergotamine

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: Concurrent use of dihydroergotamine and sympathomimetics may result in additive or synergistic effect on peripheral blood vessels.(1)

CLINICAL EFFECTS: Concurrent use of dihydroergotamine and sympathomimetics may result in increased blood pressure due to peripheral vasoconstriction.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Dihydroergotamine is contraindicated with sympathomimetics because the combination may result in additive or synergistic elevation of blood pressure.(1)

DISCUSSION: Significant elevation in blood pressure has been reported in patients treated with dihydroergotamine.(1) Sympathomimetics can be expected to have additional effects on blood pressure.

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

Agents That Affect Catecholamines/Iobenguane I 123

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

MECHANISM OF ACTION: Many compounds that reduce catecholamine uptake or that deplete catecholamine stores may interfere with iobenguane uptake into cells.(1)

CLINICAL EFFECTS: Compounds that reduce catecholamine uptake or that deplete catecholamine stores may interfere with imaging completed with iobenguane.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Discuss the use of agents that affect catecholamines. Discontinue drugs that reduce catecholamine uptake or deplete catecholamine stores prior to imaging with iobenguane. Before imaging with iobenguane, discontinue agents that affect catecholamines for at least 5 biological half-lives, as clinically tolerated.(1)

DISCUSSION: Many agents may reduce catecholamine uptake or deplete catecholamine stores.(1) Examples include: - CNS stimulants or amphetamines (e.g. cocaine, methylphenidate, dextroamphetamine) - norepinephrine and dopamine reuptake inhibitors (e.g. phentermine) - norepinephrine and serotonin reuptake inhibitors (e.g. tramadol) - monoamine oxidase inhibitors (e.g. phenelzine, linezolid) - central monoamine depleting drugs (e.g. reserpine) - non-select beta adrenergic blocking drugs (e.g. labetalol) - alpha agonists or alpha/beta agonists (e.g. pseudoephedrine, phenylephrine, ephedrine, phenylpropanolamine, naphazoline) - tricyclic antidepressants or norepinephrine reuptake inhibitors (e.g. amitriptyline, bupropion, duloxetine, mirtazapine, venlafaxine) - botanicals that may inhibit reuptake of norepinephrine, serotonin or dopamine (e.g. ephedra, ma huang, St. John's Wort, yohimbine)

Agents That Affect Catecholamines/Iobenguane I 131

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

MECHANISM OF ACTION: Many compounds that reduce catecholamine uptake or that deplete catecholamine stores may interfere with iobenguane uptake into cells.(1)

CLINICAL EFFECTS: Compounds that reduce catecholamine uptake or that deplete catecholamine stores may impact the dosimetry calculations or effectiveness of iobenguane.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Discuss the use of agents that affect catecholamines. Discontinue drugs that reduce catecholamine uptake or deplete catecholamine stores for at least 5 half-lives before administration of either the dosimetry or a therapeutic dose of iobenguane. Do not administer these drugs until at least 7 days after each iobenguane dose.(1)

DISCUSSION: Many agents may reduce catecholamine uptake or deplete catecholamine stores.(1) Examples include: - CNS stimulants or amphetamines (e.g. cocaine, methylphenidate, dextroamphetamine) - norepinephrine and dopamine reuptake inhibitors (e.g. phentermine) - norepinephrine and serotonin reuptake inhibitors (e.g. tramadol) - monoamine oxidase inhibitors (e.g. phenelzine, linezolid) - central monoamine depleting drugs (e.g. reserpine) - non-select beta adrenergic blocking drugs (e.g. labetalol) - alpha agonists or alpha/beta agonists (e.g. pseudoephedrine, phenylephrine, ephedrine, phenylpropanolamine, naphazoline) - tricyclic antidepressants or norepinephrine reuptake inhibitors (e.g. amitriptyline, bupropion, duloxetine, mirtazapine, venlafaxine) - botanicals that may inhibit reuptake of norepinephrine, serotonin or dopamine (e.g. ephedra, ma huang, St. John's Wort, yohimbine) - calcium channel blockers

Selected Direct-Acting Sympathomimetics/Tricyclic Compounds

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

MECHANISM OF ACTION: Unknown. However, it is speculated that direct-acting sympathomimetic amines have an enhanced effect due to tricyclic blockage of norepinephrine reuptake.

CLINICAL EFFECTS: Increased effect of direct acting sympathomimetics.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Consider avoiding the concurrent use of direct-acting sympathomimetics and tricyclic compounds. If concurrent use of direct-acting sympathomimetics and tricyclic compounds is warranted, the initial dose of the sympathomimetic should be lowered and the patient should be monitored for adverse cardiovascular effects. Use of tricyclic compounds and other sympathomimetics should be approached with caution.

DISCUSSION: Epinephrine and other direct-acting sympathomimetic amines exert enhanced cardiovascular effects (e.g., arrhythmias, hypertension, and tachycardia) in individuals concurrently receiving or previously treated with tricyclic antidepressants. Other direct and mixed acting sympathomimetic amines have also been reported to interact with tricyclic antidepressants. These include norepinephrine, phenylephrine, dopamine, and methoxamine. Protriptyline, amitriptyline, and desipramine have also been reported to interact with direct-acting sympathomimetics.

Sympathomimetics/Ergot Alkaloids

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

MECHANISM OF ACTION: Concurrent use of ergot alkaloids and sympathomimetics may result in additive or synergistic effect on peripheral blood vessels.

CLINICAL EFFECTS: Concurrent use of ergot alkaloids and sympathomimetics may result in increased blood pressure due to peripheral vasoconstriction.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: When possible, avoid the concurrent use of ergot alkaloids and sympathomimetics. If concurrent use is warranted, monitor blood pressure and for signs of vasoconstriction. Decreasing the dose of one or both drugs may be necessary.

DISCUSSION: There have been reports of severe vasoconstriction resulting in gangrene in patients receiving intravenous ergonovine with dopamine or norepinephrine.

Sympathomimetics/Selected Inhalation Anesthetic Agents

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

MECHANISM OF ACTION: The exact mechanism is unknown. The anesthetics produce conduction changes that increase impulse re-entry into the myocardial tissue.(1) The anesthetics' ability to precipitate arrhythmias is enhanced by elevated arterial blood pressure, tachycardia, hypercapnia, and/or hypoxia, events that stimulate the release of endogenous catecholamines.(1)

CLINICAL EFFECTS: Concurrent use of inhalation anesthetic agents and sympathomimetics may result in ventricular arrhythmias or sudden blood pressure and heart rate increase during surgery.(2)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Monitor blood pressure and avoid use of sympathomimetics in patients being treated with anesthetics on the day of surgery.(2) Intravenous use of epinephrine during surgery with halothane and related halogenated general anesthetics should be strongly discouraged. When intravenous epinephrine is necessary, nitrous oxide anesthesia supplemented with ether, muscle relaxants, or opioids should be used instead of halothane.(3,4) Epinephrine may safely be used subcutaneously with the following precautions: the patient is adequately ventilated to prevent hypoxia or respiratory acidosis; the total dose of epinephrine is limited to 100 mcg/10 minute period or 300 mcg/hour in adults, 3.5 mcg/Kg in infants, 2.5 mcg/Kg in children up to two years of age, and 1.45 mcg/Kg in children over two years of age; a minimum effective concentration of anesthetic is maintained; the drugs are not co-administered in patients with hypertension or other cardiovascular disorders; and the cardiac rhythm is continuously monitored during and after injection.(3-10) If arrhythmias occur after the administration of the epinephrine, the drugs of choice are lidocaine or propranolol, depending on the type of arrhythmia.(1)

DISCUSSION: Administration of epinephrine during halothane anesthesia may may lead to serious ventricular arrhythmias.(3-6,11-18) This has occurred when epinephrine was administered intravenously,(6) when it was administered with lidocaine as a dental block,(11,14) or when it was administered supraperiosteally.(5) Norepinephrine has been shown to interact with halothane in a manner similar to epinephrine.(1) In two case reports, patients were given terbutaline (0.25 to 0.35 mg) for wheezing following induction of anesthesia with halothane. One patient's heart rate increased from 68 to 100 beats/minute, and the ECG showed premature ventricular contractions and bigeminy, while the other patient developed multiple unifocal premature ventricular contractions and bigeminy. The arrhythmias resolved in both patients following lidocaine administration.(19) Although not documented, isoproterenol causes effects on the heart similar to terbutaline(20) and would probably interact with halothane in a similar manner. Other inhalation anesthetics that increase the incidence of arrhythmias with epinephrine include chloroform,(20) methoxyflurane,(20) and enflurane.(12) A similar interaction may be expected between the other inhalation anesthetics and sympathomimetics.

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

Beta-Agonists; Anticholinergics; Theophylline/Methacholine

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

MECHANISM OF ACTION: Beta-agonists, anticholinergics, and theophylline may inhibit the action of methacholine on the airway.(1)

CLINICAL EFFECTS: The result of the methacholine challenge test may not be accurate.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The following drugs should be held before a methacholine challenge for the the duration indicated:(1) - short-acting beta-agonists: 6 hours - long-acting beta-agonists: 36 hours - short-acting anti-cholinergics: 12 hours - long-acting anti-cholinergics: at least 168 hours (7 days) - oral theophylline: 12-48 hours

DISCUSSION: Beta-agonists, anticholinergics, and theophylline may inhibit the action of methacholine on the airway and cause inaccurate test results.

Comt-Metabolized Agents/Entacapone; Opicapone

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

MECHANISM OF ACTION: Entacapone and opicapone are selective and reversible inhibitors of catechol-O-methyltransferase (COMT) and drugs that are metabolized by COMT can not be fully metabolized when given with entacapone or opicapone.(1)

CLINICAL EFFECTS: COMT-metabolized agents can interact with entacapone or opicapone and may result in an increased heart rates, arrhythmias, or an excessive change in blood pressure.(1)

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: The manufacturers of entacapone and opicapone recommend using caution when administering entacapone or opicapone and a COMT-metabolized agent regardless of the route of administration (including inhalation).(1-3)

DISCUSSION: In an interaction study, ventricular tachycardia was observed after epinephrine and entacapone administration.(1) Another study on the effect of entacapone given with isoproterenol and epinephrine concluded that entacapone may potentiate the chronotropic and arrhythmogenic effects of isoproterenol and epinephrine.(4)

Sympathomimetics (Direct, Mixed-Acting)/Methyldopa

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

MECHANISM OF ACTION: Unknown.

CLINICAL EFFECTS: The pressor response to sympathomimetics may be increased.

PREDISPOSING FACTORS: None determined.

PATIENT MANAGEMENT: Start with low doses of sympathomimetics and monitor blood pressure of patients during concurrent administration of sympathomimetics and methyldopa.

DISCUSSION: The pressor response to sympathomimetics has been reported to be increased during methyldopa administration. In addition to increased duration of pressor response, severe hypertension has been reported.

*Angina pectoris.

*Ventricular arrhythmias.

*Tachycardia.

• Angina
• Digitalis toxicity with AV conduction defects
• Tachyarrhythmia
• Tachycardia due to digitalis toxicity

• Acute myocardial infarction
• Atrioventricular conduction defect
• Chronic myocardial ischemia
• Coronary artery disease
• Hypertension

• Diabetes mellitus
• Hyperthyroidism

Common adverse effects with isoproterenol include tachycardia and palpitations.

Rare or Very Rare

• Cardiac arrhythmia
• Chest pain
• Paradoxical bronchospasm

More Frequent

• Insomnia
• Nervousness
• Xerostomia

Less Frequent

• Dizziness
• Flushing
• General weakness
• Headache disorder
• Hyperhidrosis
• Hypertension
• Nausea
• Tachycardia
• Tremor
• Vomiting

No enhanced messaging available.

The safety and efficacy of isoproterenol hydrochloride in pediatric patients have not been established. However, the drug has been used in pediatric patients+ for certain conditions.

IV infusions of isoproterenol hydrochloride (0.05-2.7 mcg/kg per minute) in pediatric patients with refractory asthma have caused clinical deterioration, myocardial necrosis, congestive heart failure (CHF), and death. The risk of developing such cardiac toxicity may be increased by acidosis, hypoxia, and/or concomitant use of other agents such as xanthine derivatives or corticosteroids, drugs that are likely to be used in these children. If IV isoproterenol is used in pediatric patients with refractory asthma, vital signs should be monitored continuously, ECG monitored frequently, and cardiac-specific serum isoenzyme MB concentrations of serum CK (CPK) should be determined daily.

Based on published literature, prolonged experience with isoproterenol use in pregnant women spanning several decades has not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

Hypotension associated with shock during pregnancy constitutes a medical emergency and may be fatal if not promptly treated. Delayed management of hypotension in pregnant patients with shock may increase the risk of maternal and fetal morbidity and mortality. Accordingly, life-sustaining therapy for the pregnant patient should not be withheld due to potential concerns regarding fetal effects of isoproterenol.

The use of isoproterenol during labor and delivery is associated with risks to both the mother and the fetus. Isoproterenol generally inhibits spontaneous and oxytocin-induced uterine contractions and may prolong the second stage of labor. Use of isoproterenol should be avoided during the second stage of labor and in obstetric settings when maternal blood pressure exceeds 130/80 mmHg. Although isoproterenol may improve maternal hypotension associated with shock, it may also cause uterine vasoconstriction, reduced uterine blood flow, uterine atony with hemorrhage, and fetal anoxia.

There are no available data regarding the presence of isoproterenol in human milk, its effects on the breast-fed infant, or its impact on milk production. However, given the short elimination half-life of isoproterenol, infant exposure through breast milk is anticipated to be minimal.

The manufacturer makes no specific dosage recommendations for geriatric patients. In general, dosage should be titrated carefully in geriatric patients, usually initiating therapy at the low end of the dosage range. The greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy observed in the elderly also should be considered.

Clinical studies of isoproterenol hydrochloride did not include sufficient numbers of patients 65 years of age and older to determine whether geriatric patients respond differently than younger patients. Some data suggest that geriatric healthy individuals or hypertensive patients are less responsive to beta-adrenergic stimulation than younger adults. In general, dosage should be titrated carefully in geriatric patients, usually initiating therapy at the low end of the dosage range. The greater frequency of decreased hepatic, renal, and/or cardiac function and of concomitant disease and drug therapy observed in the elderly also should be considered.