scopolamine
Brand: Transderm Scop
Beers Criteria
Drug Class: anticholinergic / antiemetic
Drug Family: antiemetic
Subclass: muscarinic antagonist (motion sickness)
Organ Systems: gastrointestinalcns
Mechanism of Action
Competitive antagonist of muscarinic M1 receptors in the vestibular nucleus and vomiting center, blocking acetylcholine-mediated signals from the vestibular apparatus that trigger motion sickness. Also reduces GI motility and secretions via peripheral muscarinic blockade.
M1 muscarinic receptors (vestibular nucleus, vomiting center)
Indications
- motion sickness (prevention)
- PONV (prevention)
- nausea associated with surgery
Contraindications
- narrow-angle glaucoma
- urinary retention
- pyloric obstruction
- myasthenia gravis
Adverse Effects
Common
- dry mouth
- drowsiness
- blurred vision
- urinary retention
- constipation
- confusion
Serious
- anticholinergic toxidrome (high doses)
- acute angle-closure glaucoma
- psychosis/hallucinations (elderly)
Pharmacokinetics (ADME)
| Absorption | transdermal patch delivers drug over 72 hours; also available oral and injectable |
| Distribution | highly lipophilic; crosses BBB readily |
| Metabolism | hepatic hydrolysis and conjugation |
| Excretion | renal (<10% unchanged) |
| Half-life | 9.5 hours |
| Onset | 4 hours (patch) |
| Peak | 24 hours (patch) |
| Duration | 72 hours (patch) |
| Protein Binding | ~50% |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| anticholinergic agents | additive anticholinergic toxicity | major |
| CNS depressants | additive sedation | moderate |
| antipsychotics | additive anticholinergic effects | moderate |
Nursing Considerations
- Apply transdermal patch behind the ear at least 4 hours before travel or surgery; each patch lasts 72 hours.
- Wash hands thoroughly after handling patch to avoid inadvertent eye contact (causes pupil dilation and blurred vision).
- Assess for glaucoma, urinary retention, and prostatic hypertrophy before prescribing; these are contraindications.
- Advise patients on the Beers Criteria listing; avoid in elderly patients due to confusion, urinary retention, and fall risk.
Clinical Pearls
- Scopolamine is highly effective for motion sickness because it targets the root cause — vestibular-to-vomiting center signaling — rather than the emetic response itself.
- The transdermal formulation provides sustained drug delivery while avoiding first-pass metabolism, resulting in a convenient and effective delivery method.
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.