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# Hyoscine butylbromide (Buscopan)
## Overview
Hyoscine butylbromide is a quaternary ammonium antispasmodic agent. Unlike hyoscine hydrobromide, it does not cross the blood-brain barrier effectively, resulting in a low incidence of central nervous system (CNS) side effects at therapeutic doses. It acts as a peripheral muscarinic antagonist to reduce smooth muscle spasms in the gastrointestinal, biliary, and urinary tracts.
## Primary Indications
* Symptomatic relief of gastrointestinal and genitourinary smooth muscle spasms (pain associated with irritable bowel syndrome, biliary colic, or renal colic).
* Abdominal cramping.
## Adult Dosing
* **Oral:** 10–20 mg three to four times daily. Maximum: 100 mg/day.
* **IM/IV/SC:** 20 mg as a single dose; may repeat after 30 minutes if necessary. Maximum: 100 mg/day.
## Pediatric Dosing
* **Children 6–12 years:** 10 mg orally three times daily.
* **Under 6 years:** Not generally recommended for self-administration.
* *Note:* Pediatric dosing varies by local institutional protocol; confirm with local formulary guidelines.
## Dose Adjustments
* **Renal/Hepatic Impairment:** No formal standardized dosing adjustments exist; however, use with caution due to the risk of systemic anticholinergic accumulation. Start at the lower end of the dosing range.
## Contraindications
* Hypersensitivity to hyoscine butylbromide.
* Myasthenia gravis.
* Megacolon or paralytic ileus.
* Narrow-angle glaucoma.
* Prostatic hypertrophy with urinary retention.
* Tachycardia or unstable cardiovascular status.
## Adverse Effects
* **Common:** Dry mouth, xerophthalmia (dry eyes), tachycardia, constipation, urinary retention.
* **Serious:** Anaphylaxis, visual disturbances (mydriasis/cycloplegia), confusion (rare, mostly in elderly).
## Key Drug Interactions
* **Anticholinergics:** Concurrent use with tricyclic antidepressants, antihistamines, or antipsychotics increases the risk of additive anticholinergic effects (e.g., urinary retention, constipation).
* **Metoclopramide:** Antagonistic effects on GI motility; avoid concurrent use.
* **Digoxin:** May increase digoxin absorption due to reduced gastric motility.
## Monitoring
* Monitor for signs of anticholinergic toxicity (urinary retention, severe constipation, altered mental status).
* Assess effectiveness of pain relief.
* In the elderly, monitor closely for cognitive impairment or falls due to blurred vision.
## Clinical Pearls
* **CNS profile:** Because it is a quaternary ammonium compound, it does not cross the blood-brain barrier; if CNS side effects occur, consider a differential diagnosis other than hyoscine butylbromide.
* **Injection administration:** IV administration may cause transient tachycardia; consider slow injection.
* **Diagnostic use:** Sometimes utilized in radiology for hypotonic duodenography, but this requires higher doses and close cardiovascular monitoring.
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*Disclaimer: This information is for educational purposes only. Always verify current prescribing information, dose calculations, and contraindications through local clinical formularies, validated drug databases (e.g., Lexicomp, BNF), or a staff clinical pharmacist prior to administration.*
