Phenobarb-Hyoscy-Atropine-Scop (phenobarbital/hyoscyamine sulf/atropine sulf/scopolamine Hb)

Dosage of phenobarbital must be individualized for each patient. Total daily dose should not exceed 600 mg. Following chronic administration, the drug should be withdrawn slowly to avoid the possibility of precipitating withdrawal symptoms if the patient is physically dependent on the drug.

Dosage of atropine sulfate should be individualized based on indication, patient characteristics, and response (e.g., heart rate, blood pressure); pediatric patients tend to be more susceptible than adults to the toxic effects of atropine overdosage.

Phenobarbital is administered orally. Phenobarbital sodium is administered by IM or slow IV injection. Parenteral solutions prepared from sterile phenobarbital sodium powder, but not the commercially available injections, may also be injected subcutaneously. Subcutaneous injection or extravasation of the commercially available injections causes tissue irritation, which can result in local reactions varying in severity from slight redness and tenderness to necrosis. If such extravasation or inadvertent injection occurs, treatment that includes application of moist heat and injection of 0.5% procaine hydrochloride at the affected site has been recommended.

IV administration of the drug should be reserved for emergency treatment of acute seizure states; however, usefulness of the drug in these conditions is limited. (See Uses.) When the drug is administered IV, the patient should be hospitalized and under close supervision. The drug must be administered IV slowly at a rate not greater than 60 mg/minute. Inadvertent intra-arterial injection of commercially available phenobarbital sodium injections can cause spasm and severe pain along the affected artery, which can result in local reactions varying in severity from transient pain to gangrene. The injection should be stopped if the patient complains of pain or if signs of inadvertent intra-arterial injection occur, such as patches of discolored skin, a white hand with cyanosed skin, or delayed onset of action. The most appropriate therapy for such inadvertent injection has not been fully established, and the manufacturers' labeling should be consulted for current recommendations.

Hyoscyamine is administered orally. Hyoscyamine sulfate is usually administered orally or sublingually. Hyoscyamine sulfate also may be administered by IV, IM, or subcutaneous injection when oral or sublingual administration is not feasible or when rapid therapeutic effect is necessary. Hyoscyamine sulfate is commercially available as conventional (immediate-release) tablets, extended-release capsules and tablets, oral solutions (drops), elixirs, sublingual tablets, orally disintegrating tablets, and injection.

Immediate-release preparations of hyoscyamine sulfate (conventional, sublingual, or orally disintegrating tablets; oral solutions (drops); elixirs) generally are administered orally or sublingually 3-6 times daily.

Extended-release preparations of hyoscyamine sulfate should not be crushed or chewed. Symax(R) SR and Symax(R) DuoTab(R) tablets should be swallowed whole, while Levbid(R) tablets and certain generic preparations are scored and may be broken in order to titrate dosage. Extended-release preparations generally are administered every 12 hours, but preparations that are not scored may be administered every 8 hours if dosage adjustment is required. Patients should be advised that extended-release preparations may not completely disintegrate and fragments may be excreted in stools in some patients.

Sublingual tablets of hyoscyamine sulfate (i.e., Levsin(R)/SL, Symax(R) SL, generic preparations) may be administered sublingually or orally. Certain sublingual tablets (e.g., Levsin(R)/SL, certain generic preparations) also may be chewed. The manufacturers of Levsin(R)/SL and certain generic preparations state that oral administration of the sublingual tablets results in similar pharmacologic effects as sublingual administration, although the onset may not be as rapid.

Orally disintegrating tablets of hyoscyamine sulfate (i.e., NuLev(R), Symax(R) FasTab(R), generic preparations) are administered by placing a tablet on the tongue to dissolve and be swallowed with the saliva; orally disintegrating tablets may be administered with or without water. Individuals with phenylketonuria (i.e., homozygous genetic deficiency of phenylalanine hydroxylase) and other individuals who must restrict their intake of phenylalanine should be warned that each 0.125-mg NuLev(R), Symax(R) FasTab(R), or generic hyoscyamine sulfate (marketed by Ethex) orally disintegrating tablet contains aspartame (NutraSweet(R)), which is metabolized in the GI tract to provide about 1.7, 4.5, or 0.5 mg, respectively, of phenylalanine following oral administration.

Because antacids may decrease absorption of oral hyoscyamine sulfate when these drugs are administered simultaneously, most manufacturers recommend administration of hyoscyamine sulfate before meals and administration of antacids postprandially. One manufacturer recommends routine administration of hyoscyamine sulfate (Symax(R) formulations) 30-60 minutes before meals.

Hyoscyamine sulfate injection may be administered by IV, IM, or subcutaneous injection without prior dilution. Parenteral hyoscyamine sulfate solutions should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.

Scopolamine hydrobromide is administered orally or by IM, direct IV, or subcutaneous injection. Scopolamine is administered percutaneously by topical application of a transdermal system (Transderm Scop(R)).

For direct IV administration, scopolamine hydrobromide injection should be diluted with sterile water for injection prior to administration. When given as a preoperative medication, scopolamine hydrobromide injection is given 30-60 minutes prior to the anticipated time of induction of anesthesia or at the time other preanesthetic medications (e.g., opiates, sedatives) are administered. When scopolamine hydrobromide is administered orally or IM for the prevention of motion sickness, the drug should generally be administered 1 hour (range: 0.5-1.5 hours) before anticipated exposure to motion.

When scopolamine is administered percutaneously as the transdermal system for the prevention of motion sickness, the system should be applied topically at least 4 hours (e.g., 4-24 hours) before anticipated exposure to motion.

For prevention of postoperative nausea and vomiting, transdermal scopolamine should be applied the evening before scheduled surgery. If transdermal scopolamine is used prophylactically in patients undergoing cesarean section, the drug should be applied one hour prior to surgery to minimize exposure of the fetus to the drug. Patients should be carefully instructed in the use of transdermal scopolamine. To obtain optimum results, patients also should be given a copy of the patient instructions provided by the manufacturer. The scopolamine transdermal system should not be cut, and only one transdermal system should be worn at any time.

Prior to administration of the transdermal system, the area behind the ear should be wiped with a clean, dry tissue to ensure that the area is dry. To expose the adhesive surface of the system, the clear plastic protective strip should be peeled and discarded prior to administration; finger contact with the exposed adhesive layer should be avoided to prevent contamination of the fingers with scopolamine. The transdermal system is applied topically to a dry, hairless area of skin behind the ear (postauricular) by firmly pressing the system with the adhesive side touching the skin. Patients should be warned to thoroughly wash their hands after handling (e.g., initial application, removal) the scopolamine transdermal system, since contamination of fingers and subsequent contact with the eyes may result in cycloplegia (i.e., mydriasis and blurred vision). Individuals who assist the patient in the application or removal of the transdermal system also should thoroughly wash their hands with soap and water afterwards. If the system becomes dislodged during the intended period of use (up to 72 hours), it should be removed and replaced with another system at a different postauricular site. The system is generally not affected by limited exposure to water (e.g., during bathing or swimming). Following removal of the transdermal system, the application site should be thoroughly washed with soap and water to remove any traces of scopolamine that might remain on the skin.

Atropine sulfate is administered by IM, subcutaneous, or direct IV administration. IV administration is preferred for the treatment of severe or life-threatening muscarinic effects.

Atropine also has been administered by intraosseous (IO) injection+ in the setting of advanced cardiovascular life support (ACLS), generally when IV access is not readily available; onset of action and systemic concentrations are comparable to those achieved with venous administration.

Atropine may be administered via an endotracheal tube when vascular access (IV or IO) is not possible; however, IV or IO administration is preferred because of more predictable drug delivery and pharmacologic effect. (See Pharmacokinetics: Absorption.)

Atropine sulfate has been administered orally; however, an oral dosage form no longer is commercially available in the US.

Atropine sulfate has been administered by oral inhalation using a nebulizer solution; however, a solution for oral inhalation no longer is commercially available in the US.

No dosing information is available for this tab.

No dosing information is available for this tab.

There is no enhanced messaging for this drug.

There are no contraindication interactions for this drug.

There are no severe interactions for this drug.

There are no moderate interactions for this drug.

There is no enhanced messaging for this drug.

There are no contraindication contraindications for this drug.

There are no severe contraindications for this drug.

There are no moderate contraindications for this drug.

There is no enhanced messaging for this drug.

There are no severe adverse reactions for this drug.

There are no less severe adverse reactions for this drug.

Phenobarbital shares the toxic potentials of the barbiturates, and the usual precautions of barbiturate administration should be observed. (See Cautions in the Barbiturates General Statement 28:24.04.)

IV phenobarbital sodium may cause respiratory depression, particularly if the drug is administered too rapidly. The drug must be administered slowly at a rate not greater than 60 mg/minute, and personnel and equipment should be readily available for administration of artificial respiration.

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Reproduction studies in rats and rabbits using IV scopolamine hydrobromide at dosages producing plasma concentrations of the drug 100 times greater than those achievable after application of the transdermal system in humans have shown a marginal embryotoxic effect in rabbits; no teratogenic effects were observed in rats. Scopolamine does not increase the duration of labor or affect uterine contractions during labor following parenteral administration; however, the drug crosses the placenta. Although one manufacturer states that adverse fetal effects have not been reported to date when scopolamine was used during labor and delivery, fetal toxicity, including tachycardia, fever, and lethargy, which responded to treatment with physostigmine, were reported in one infant following maternal administration of a total dosage of 1.8 mg of scopolamine during labor and delivery. Decreased heart rate variability and decreased heart rate deceleration also have been reported in infants of mothers who received scopolamine during labor and delivery. However, in one clinical study in women undergoing cesarean sections, adverse effects, including CNS depression, were not observed in neonates when transdermal scopolamine was used concomitantly with epidural anesthesia and opiate analgesics. There are no adequate and controlled studies to date using scopolamine in pregnant women, and the drug should be used during pregnancy only when the potential benefits justify the possible risks to the fetus.

Scopolamine is distributed into milk. Although some manufacturers recommend that scopolamine be used with caution in nursing women, no observable change in infants associated with such exposure has been reported to date, and the American Academy of Pediatrics (AAP) considers scopolamine to be usually compatible with breast-feeding.

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