Pharmacology · Antimuscarinics (anticholinergics)
Hyoscine hydrobromide (scopolamine) !
A belladonna alkaloid that enters the brain; a skin patch prevents motion sickness. In Colombia it is also known for criminal poisoning («burundanga»).
Updated 2026-11-01
Also called: Scopolamine, L-hyoscine
No structure of scopolamine bound to its receptor exists. The figure shows N-methylscopolamine, the quaternary form of scopolamine and a close relative, in the acetylcholine (orthosteric) pocket of the human M2 muscarinic receptor; all muscarinic subtypes share this pocket.
Mechanism of action
Scopolamine competitively blocks muscarinic receptors in the periphery and, being a tertiary amine, in the brain. Blocking cholinergic signals from the vestibular nuclei to higher centres and to the vomiting centre prevents motion sickness. Compared with atropine it has stronger effects on the eye and glands and depresses the brain (drowsiness, amnesia) rather than stimulating it at usual doses; high doses cause delirium.
- Absorbed through the skin and enters the brain
- Blocks muscarinic signals from the vestibular nuclei
- The vomiting centre is not triggered by motion
- Also dries secretions; high doses cause amnesia and delirium
Pharmacokinetics
- Absorption
- Well absorbed through the skin behind the ear from a patch; also given by injection
- Distribution
- Crosses the blood-brain barrier and the placenta
- Elimination
- Levels fall steadily after the patch is removed; withdrawal symptoms can start a day or more later
Indications
- Prevention of nausea and vomiting of motion sickness (patch)
- Prevention of postoperative nausea and vomiting (patch)
- Symptom control in palliative care, patch or injection (WHO Essential Medicines List)
Adverse effects
Common
- Dry mouth
- Drowsiness and dizziness
- Blurred vision and dilated pupils, especially if the eye is touched after handling the patch
- Confusion and agitation, more in older adults
Contraindications
- Angle-closure glaucoma
- Hypersensitivity to scopolamine or other belladonna alkaloids
Key interactions
- Alcohol, sedatives, opioids and anxiolytics
- More drowsiness and disorientation
- Other anticholinergic drugs (antihistamines, meclizine, tricyclics)
- Higher risk of delirium, bowel obstruction and urinary retention
- Oral drugs with a narrow therapeutic range
- Slower stomach emptying can change their absorption
What is monitored
- Mental status and new psychiatric symptoms
- Temperature in heat, exercise or fever
- Eye pain or vision change
- Bladder and bowel function
Administration and safety
- The patch goes on clean, dry, hairless skin behind the ear; hands are washed after handling it
- Removed before an MRI scan: the aluminised layer can burn the skin
- Not cut; one patch at a time
Nursing care
- Teach handwashing after touching the patch to avoid a dilated, blurry eye
- Watch older adults for confusion and falls
- Warn about driving and alcohol
- After several days of use, removal can cause dizziness, nausea, headache and slow pulse
Pregnancy and breastfeeding
Observational data have not shown a higher risk of major birth defects; it is avoided in severe preeclampsia because of eclamptic seizures.
Test yourself
Think of the answer, then tap the question to see it.
Where is the scopolamine patch applied?
On clean, dry, hairless skin behind the ear.
Why must a scopolamine patch be removed before an MRI?
It contains an aluminised layer that can cause skin burns during the scan.
How does scopolamine differ from hyoscine butylbromide?
Scopolamine is tertiary and enters the brain (motion sickness, sedation, delirium); the butylbromide is quaternary and acts only in the periphery (gut cramps).
Which antidote reverses severe central scopolamine poisoning?
Physostigmine, with supportive care.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - SCOPOLAMINE patch, extended release (DailyMed (U.S. National Library of Medicine), 2026); Scopolamine Transdermal Patch: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Comportamiento de las intoxicaciones con escopolamina durante 2021-2022 (Secretaría Distrital de Salud de Bogotá (Boletín Epidemiológico Distrital), 2022); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.