[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antimuscarinics (anticholinergics)](https://durgical.com/en/pharmacology/classes/antimuscarinics/) › Hyoscine butylbromide [Pharmacology](https://durgical.com/en/pharmacology/) · [Antimuscarinics (anticholinergics)](https://durgical.com/en/pharmacology/classes/antimuscarinics/) # Hyoscine butylbromide A gut antispasmodic widely used in Colombia for cramping abdominal pain. It is a quaternary drug that does not enter the brain. Updated 2026-11-01 - Class: [Antimuscarinics (anticholinergics)](https://durgical.com/en/pharmacology/classes/antimuscarinics/) - Receptor: Muscarinic acetylcholine receptors of smooth muscle (mainly M3) - ATC code: A03BB01 - WHO Model List of Essential Medicines Also called: Butylscopolamine, Scopolamine butylbromide ◎**Muscarinic acetylcholine receptors of smooth muscle (mainly M3)**Hyoscine butylbromide ⓘ No structure of hyoscine butylbromide 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. **Target in 3D:** Muscarinic acetylcholine receptors of smooth muscle (mainly M3). PDB structure 5ZK8 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/5ZK8) · Drag to rotate · pinch to zoom ## Mechanism of action Adding a butyl group to scopolamine makes a charged quaternary molecule. It blocks muscarinic receptors on the smooth muscle of the gut, so spasm and cramping ease; it acts on the cause of the pain (the spasm) rather than masking pain like an analgesic. Because it is charged it is poorly and unreliably absorbed by mouth and does not cross the blood-brain barrier, so it causes no drowsiness or confusion; quaternary derivatives also have some ganglion-blocking activity. - Blocks muscarinic receptors on gut smooth muscle - Acetylcholine can no longer trigger contraction - Spasm and cramping pain ease - Stays out of the brain (quaternary) ## Pharmacokinetics **Absorption** Poorly and unreliably absorbed by mouth; injections act more reliably **Distribution** Does not cross the blood-brain barrier ## Indications - Cramping abdominal pain from spasm of the gut - Symptom control in palliative care (WHO Essential Medicines List) ## Adverse effects ### Common - Dry mouth - Fast heart rate - Blurred vision - Urinary hesitancy, constipation ### Serious (rare, important) - Urinary retention (class) - Acute angle-closure glaucoma (class) - Fast heart rate, a concern in heart disease (class) - Allergic reactions, including anaphylaxis (class) ## Contraindications - Angle-closure glaucoma - Urinary retention or bladder outlet obstruction (for example an enlarged prostate) - Mechanical obstruction of the gut, paralytic ileus or toxic megacolon - Myasthenia gravis - Unstable heart status with fast heart rate (class precaution) ## Key interactions **Other anticholinergic drugs (tricyclics, antihistamines, antipsychotics)** Additive dry mouth, retention and constipation **Metoclopramide** Opposite effects on gut motility (class) ## What is monitored - Heart rate, especially after injection - Urine output and bladder in older men - Pain that persists or worsens is reassessed for another cause ## Administration and safety - Tablets or injection; injection gives the more reliable effect - In Colombia it is sold both with and without prescription; it should not be confused with scopolamine (hyoscine hydrobromide) ## Nursing care - Ask about glaucoma, prostate problems and heart disease before giving it - Check pulse after injection - Teach to report eye pain with red eye and blurred vision, or inability to pass urine ## Pregnancy and breastfeeding Data in pregnancy are limited; it is used only when the benefit justifies it. ## Memory aid The «butyl» lock keeps hyoscine out of the brain: belly cramps, no confusion. ## Test yourself Think of the answer, then tap the question to see it. ## Why does hyoscine butylbromide not cause drowsiness or confusion, unlike scopolamine? It is a quaternary (charged) molecule that does not cross the blood-brain barrier. ## Why does oral hyoscine butylbromide act less reliably than the injection? Quaternary antimuscarinics are poorly and unreliably absorbed from the gut. ## Which eye disease must be asked about before giving it? Angle-closure glaucoma. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/hyoscine-butylbromide/) ## Related drugs - [Hyoscine hydrobromide (scopolamine)](https://durgical.com/en/pharmacology/hyoscine-hydrobromide/) - [Dicycloverine](https://durgical.com/en/pharmacology/dicycloverine/) - [Atropine](https://durgical.com/en/pharmacology/atropine/) [← Back to the class: Antimuscarinics (anticholinergics)](https://durgical.com/en/pharmacology/classes/antimuscarinics/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Comportamiento de las intoxicaciones con escopolamina durante 2021-2022](https://revistas.saludcapital.gov.co/index.php/BED/article/view/43) (Secretaría Distrital de Salud de Bogotá (Boletín Epidemiológico Distrital), 2022); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=A03BB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 11 (McGraw Hill, 2023). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/hyoscine-butylbromide/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/hyoscine-butylbromide/