TRANSDERM SCOP
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TRANSDERM SCOP (TRANSDERM SCOP).
Competitive antagonist at muscarinic acetylcholine receptors (M1, M2, M3 subtypes) in the vestibular system, gastrointestinal tract, and central nervous system, inhibiting vagal nerve activity and preventing motion-induced nausea and vomiting.
| Metabolism | Hepatic via cytochrome P450 (CYP) enzymes, primarily CYP3A4; undergoes N-demethylation and ester hydrolysis; metabolite scopolamine-N-oxide is active. |
| Excretion | Scopolamine is extensively metabolized; about 50% of a dose is excreted renally as metabolites and unchanged drug, with less than 10% excreted unchanged in urine. Biliary/fecal excretion accounts for approximately 30-40% of the dose. |
| Half-life | The terminal elimination half-life of scopolamine is approximately 9.5 hours (range 6-12 hours) following transdermal administration. In elderly patients, half-life may be prolonged to up to 20 hours. |
| Protein binding | Scopolamine is approximately 30-40% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | The volume of distribution of scopolamine is approximately 1.4 L/kg (range 1.0-2.0 L/kg), indicating extensive tissue distribution, including crossing the blood-brain barrier and placenta. |
| Bioavailability | Transdermal scopolamine has a bioavailability of approximately 0.5% (relative to intravenous administration) due to slow absorption and first-pass metabolism. Oral bioavailability is negligible (<1%) due to extensive first-pass metabolism, which is why transdermal route is used. |
| Onset of Action | Following application of the transdermal patch, peak plasma concentrations are reached in about 8-12 hours, with clinical antiemetic effect (motion sickness prevention) evident within 4-6 hours. For optimal effect, the patch should be applied 4-6 hours before exposure. |
| Duration of Action | The transdermal system delivers scopolamine at a constant rate for up to 72 hours. Clinical effects persist for the duration of patch wear, with continued antiemetic protection for 24-72 hours. After patch removal, effects may persist for several hours due to residual drug in the skin. |
One transdermal patch (1 mg/72 hours) applied to the hairless area behind the ear at least 4 hours before anticipated exposure; replace every 72 hours as needed.
| Dosage form | SYSTEM |
| Renal impairment | No specific dosage adjustment recommended; use with caution in severe renal impairment (CrCl < 30 mL/min) due to potential accumulation. |
| Liver impairment | No dosage adjustment necessary for Child-Pugh Class A or B. For Child-Pugh Class C, consider reducing dose or increasing dosing interval due to decreased clearance. |
| Pediatric use | Children ≥12 years: same as adult. Children <12 years: safety and efficacy not established; use not recommended. |
| Geriatric use | Elderly patients may be more sensitive to anticholinergic effects; start with lowest effective dose. Consider patch removal after 24 hours to reduce systemic exposure. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TRANSDERM SCOP (TRANSDERM SCOP).
| Breastfeeding | Scopolamine is excreted in breast milk in small amounts; M/P ratio not established. Risk of anticholinergic effects in infant (e.g., decreased heart rate, constipation). Manufacturer recommends caution; consider alternatives if breastfeeding. |
| Teratogenic Risk | Transdermal scopolamine is classified as FDA Pregnancy Category C. First trimester: Data limited; animal studies show increased resorptions and skeletal anomalies at doses 5-10x human dose. Second trimester: No specific fetal risks identified. Third trimester: Risk of neonatal anticholinergic effects (e.g., decreased heart rate, respiratory depression) if used near term. Avoid close to delivery. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to scopolamine or any component of the patch; narrow-angle glaucoma; acute hemorrhage; severe ulcerative colitis; myasthenia gravis; paralytic ileus; obstructive uropathy; following gastrointestinal or genitourinary surgery.
| Precautions | Use with caution in patients with glaucoma (risk of increased intraocular pressure), pyloric obstruction, urinary bladder neck obstruction, intestinal atony, and toxic megacolon. May cause drowsiness, blurred vision, and confusion, especially in elderly. Avoid abrupt discontinuation after prolonged use to prevent withdrawal syndrome. Do not use in patients with severe hepatic or renal impairment. |
Loading safety data…
| Fetal Monitoring | Monitor maternal heart rate and blood pressure for tachycardia or hypotension. Observe fetal heart rate for bradycardia or variability changes. Assess neonatal adaptation if used near delivery (anticholinergic withdrawal). |
| Fertility Effects | Limited data; animal studies show no adverse effects on fertility at therapeutic doses. Potential anticholinergic effect on cervical mucus or implantation not well studied. No specific human data on impaired fertility. |