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# Hyoscine butyl bromide
## Overview
Hyoscine butyl bromide (scopolamine butylbromide) is a quaternary ammonium anticholinergic agent. It does not cross the blood-brain barrier, so central nervous system effects are minimal. It acts as a spasmolytic on smooth muscle of the gastrointestinal, biliary, and urinary tracts.
## Primary Indications
- Symptomatic relief of gastrointestinal cramps and spasms (e.g., irritable bowel syndrome)
- Management of biliary or renal colic (adjunct, not first-line)
- Pre-procedure reduction of GI motility (endoscopy, radiology)
## Adult Dosing
- **Oral**: 10–20 mg three to four times daily. Maximum 60 mg/day.
- **Intramuscular/Intravenous**: 20 mg per dose, may repeat once after 30 minutes if needed. Maximum parenteral dose 100 mg/day (some protocols limit to 80 mg/day). Exact dosing depends on local institutional protocol.
## Pediatric Dosing
- **Under 6 years**: Not recommended; insufficient safety data.
- **6–12 years**: Oral 10 mg three times daily; maximum 30 mg/day. Parenteral: 0.3–0.6 mg/kg/dose as a single dose, maximum 20 mg per dose. Local protocols may vary.
## Dose Adjustments
- **Renal impairment**: No formal adjustment; use caution in severe impairment.
- **Hepatic impairment**: No data; anticholinergic effects may be more pronounced.
- **Elderly**: Start at lower oral dose (10 mg) due to increased sensitivity to anticholinergic side effects.
## Contraindications
- Myasthenia gravis
- Mechanical gastrointestinal obstruction
- Paralytic ileus
- Megacolon
- Narrow-angle glaucoma
- Tachyarrhythmias
- History of hypersensitivity to anticholinergics
- Prostatic hypertrophy with urinary retention (relative)
## Adverse Effects
- Dry mouth, constipation, blurred vision, flushing, urinary retention
- Tachycardia, palpitations
- Heat intolerance (reduced sweating)
- Rare: acute angle-closure glaucoma, paralytic ileus
- Parenteral use: hypotension, injection site reactions
## Key Drug Interactions
- **Anticholinergics** (e.g., tricyclic antidepressants, antihistamines, antipsychotics): additive anticholinergic effects.
- **Metoclopramide, domperidone**: antagonism of GI motility effects.
- **Potassium chloride** (oral, wax-matrix forms): increased risk of GI ulceration (consider liquid potassium).
- **Beta-agonists**: increased risk of tachycardia.
## Monitoring
- Clinical response (reduction in abdominal pain, spasm frequency)
- Heart rate and blood pressure (especially with parenteral use)
- Signs of anticholinergic toxicity (dry skin, dilated pupils, confusion) — more common in elderly or with overdose
## Clinical Pearls
- **No central nervous system effects** — does not cause sedation or cognitive impairment like atropine or scopolamine.
- **Onset**: Oral ~1 hour; IM/IV ~5–10 minutes; duration 4–6 hours.
- **Safe in pregnancy** (limited data but widely used; category C—use only if benefit outweighs risk).
- **In acute colic**, combine with an NSAID or paracetamol for better analgesia; not a primary analgesic.
- **Antidote for overdose**: physostigmine (only if severe anticholinergic crisis occurs—rare due to poor CNS penetration).
**Disclaimer:** This information is for educational purposes only. Always verify current prescribing information from a reliable drug formulary or local protocol before making clinical decisions. Dosing may vary based on patient-specific factors, local guidelines, and product availability.
