Scopolamine Trandermal System (Page 3 of 5)

8.2 Lactation

Risk Summary

Scopolamine is present in human milk. There are no available data on the effects of scopolamine on the breastfed infant or the effects on milk production. Because there have been no consistent reports of adverse events in breastfed infants over decades of use, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for scopolamine transdermal system and any potential adverse effects on the breastfed child from scopolamine transdermal system or from the underlying maternal condition.

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established. Pediatric patients are particularly susceptible to the adverse reactions of scopolamine; including mydriasis, hallucinations, amblyopia and drug withdrawal syndrome. Neurologic and psychiatric adverse reactions, such as hallucinations, amblyopia and mydriasis have also been reported.

8.5 Geriatric Use

Clinical trials of scopolamine transdermal system did not include sufficient number of subjects aged 65 years and older to determine if they respond differently from younger subjects. In other clinical experience, elderly patients had an increased risk of neurologic and psychiatric adverse reactions, such as hallucinations, confusion, dizziness and drug withdrawal syndrome [see Warnings and Precautions (5.2, 5.5)]. Consider more frequent monitoring for CNS adverse reactions during treatment with scopolamine transdermal system in elderly patients [see Warnings and Precautions (5.2)].

8.6 Renal or Hepatic Impairment

Scopolamine transdermal system has not been studied in patients with renal or hepatic impairment. Consider more frequent monitoring during treatment with scopolamine transdermal system in patients with renal or hepatic impairment because of the increased risk of CNS adverse reactions [see Warnings and Precautions (5.2)].

9 DRUG ABUSE AND DEPENDENCE

9.1 Controlled Substance

Scopolamine transdermal system contains scopolamine, which is not a controlled substance.

9.3 Dependence

Termination of scopolamine transdermal system, usually after several days of use, may result in withdrawal symptoms such as disturbances of equilibrium, dizziness, nausea, vomiting, abdominal cramps, sweating, headache, mental confusion, muscle weakness, bradycardia and hypotension. These withdrawal symptoms indicate that scopolamine, like other anticholinergic drugs, may produce physical dependence. The onset of these symptoms, generally 24 hours or more after the transdermal system has been removed, can be severe and may require medical intervention [see Warnings and Precautions (5.5)].

10 OVERDOSAGE

The signs and symptoms of anticholinergic toxicity include: lethargy, somnolence, coma, confusion, agitation, hallucinations, convulsion, visual disturbance, dry flushed skin, dry mouth, decreased bowel sounds, urinary retention, tachycardia, hypertension, and supraventricular arrhythmias. These symptoms can be severe and may require medical intervention.

In cases of toxicity remove the scopolamine transdermal system. Serious symptomatic cases of overdosage involving multiple transdermal system applications and/or ingestion may be managed by initially ensuring the patient has an adequate airway and supporting respiration and circulation. This should be rapidly followed by removal of all transdermal systems from the skin and the mouth. If there is evidence of transdermal system ingestion, endoscopic removal of swallowed transdermal systems, or administration of activated charcoal should be considered, as indicated by the clinical situation. In any case where there is serious overdosage or signs of evolving acute toxicity, continuous monitoring of vital signs and ECG, establishment of intravenous access, and administration of oxygen are all recommended.

The signs and symptoms of overdose/toxicity due to scopolamine should be carefully distinguished from the occasionally observed syndrome of withdrawal [see Warnings and Precautions (5.5)]. Although mental confusion and dizziness may be observed with both acute toxicity and withdrawal, other characteristic findings differ: tachyarrhythmias, dry skin, and decreased bowel sounds suggest anticholinergic toxicity, while bradycardia, headache, nausea and abdominal cramps, and sweating suggest post-removal withdrawal.

If over-exposure occurs, call your Poison Control Center at 1-800-222-1222 for current information on the management of poisoning or overdosage.

11 DESCRIPTION

Scopolamine transdermal system is designed for continuous release of scopolamine following application to an area of intact skin on the head, behind the ear. Each system contains 1.3 mg of scopolamine base. Scopolamine is (9-methyl-3-oxa-9-azatricyclo[3.3.1.02,4 ]nonan-7-yl) 3-hydroxy-2-phenylpropanoate. The empirical formula is C17 H21 NO4 and its structural formula is:

structure

Scopolamine has a molecular weight of 303.35 and a pKa of 7.55-7.81. The scopolamine transdermal system is a circular, 0.2 mm thick, 2.5 cm2 film with four layers. Proceeding from the visible surface towards the surface attached to the skin, these layers are: (1) a backing membrane of tan-colored, aluminized, polyester film; (2) a drug layer of scopolamine, crospovidone, isopropyl palmitate, light mineral oil, and polyisobutylene; (3) an ethylene vinyl acetate copolymer membrane that controls the rate of delivery of scopolamine from the system to the skin surface; and (4) an contact layer formulation of crospovidone, isopropyl palmitate, light mineral oil, polyisobutylene, and scopolamine. A release liner of siliconized polyester, which covers the adhesive layer, is removed before the system is used.

Cross section of the system:

cross-sectionstructurecross-section

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Scopolamine, a belladonna alkaloid, is an anticholinergic. Scopolamine acts: i) as a competitive inhibitor at postganglionic muscarinic receptor sites of the parasympathetic nervous system, and ii) on smooth muscles that respond to acetylcholine but lack cholinergic innervation. It has been suggested that scopolamine acts in the central nervous system (CNS) by blocking cholinergic transmission from the vestibular nuclei to higher centers in the CNS and from the reticular formation to the vomiting center. Scopolamine can inhibit the secretion of saliva and sweat, decrease gastrointestinal secretions and motility, cause drowsiness, dilate the pupils, increase heart rate, and depress motor function.

12.3 Pharmacokinetics

The system is formulated to deliver approximately 1 mg of scopolamine to the systemic circulation over 3 days.

Absorption
Following application to the skin behind the ear, circulating plasma concentrations are detected within 4 hours with peak concentrations being obtained, on average, within 24 hours. The average plasma concentration produced is 87 pg/mL (0.28 nM) for free scopolamine and 354 pg/mL for total scopolamine (free + conjugates). Following removal of the used transdermal system, there is some degree of continued systemic absorption of scopolamine bound in the skin layers.

Distribution
The distribution of scopolamine is not well characterized. It crosses the placenta and the blood brain barrier and may be reversibly bound to plasma proteins.

Elimination

Metabolism and Excretion
Scopolamine is metabolized and conjugated with less than 5% of the total dose appearing unchanged in the urine. The enzymes responsible for metabolizing scopolamine are unknown. The exact elimination pattern of scopolamine has not been determined. Following transdermal system removal, plasma concentrations of scopolamine decline in a log linear fashion with an observed half-life of 9.5 hours. Less than 10% of the total dose is excreted in the urine as the parent drug and metabolites over 108 hours.

Drug Interaction Studies

An in vitro study using human hepatocytes examined the induction of CYP1A2 and CYP3A4 by scopolamine. Scopolamine did not induce CYP1A2 and CYP3A4 isoenzymes at the concentrations up to 10 nM. In an in vitro study using human liver microsomes which evaluated the inhibition of CYP1A2, 2C8, 2C9, 2C19, 2D6 and 3A4, scopolamine did not inhibit these cytochrome P450 isoenzymes at the concentrations up to 1 micromolar. No in vivo drug-drug interaction studies have been conducted.

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