Sedative-hypnotic (thiamine analogue) Pregnancy: Contraindicated — neonatal respiratory depression, withdrawal.

Clomethiazole

Brand names: Heminevrin

Adult dose

Dose: Alcohol withdrawal (inpatient only): Day 1: 9–12 capsules (192 mg each) in 3–4 divided doses; reduce over 6 days; taper to zero by day 9. Severe insomnia in elderly (off-label, short-term): 192–384 mg ON for max 7–10 days.

Route: Oral

Frequency: QDS (withdrawal); ON (insomnia)

Max: Day 1: 12 capsules (2.3 g); avoid prolonged use (dependence)

INPATIENT alcohol withdrawal only — never community supply (overdose with alcohol is rapidly fatal). Capsules contain 192 mg; syrup 250 mg/5 ml. Strong dependence potential — risk profile worse than chlordiazepoxide.

Dose adjustments

Renal

No specific adjustment but caution.

Hepatic

Reduce dose markedly; risk of hepatic encephalopathy.

Clinical pearls

Once standard for inpatient alcohol withdrawal — now largely replaced by chlordiazepoxide (NICE CG115) due to better safety profile and lower abuse potential.
Lethal in overdose with concurrent alcohol — NEVER prescribe in community for self-administered withdrawal.
Specialist remaining indications: severe agitation in elderly with established alcohol withdrawal where benzodiazepines have failed/contraindicated; some traditional liver units retain it.
First-dose sneezing/conjunctival irritation is characteristic but harmless; warn patient.
Always co-prescribe Pabrinex (parenteral B vitamins) before/with — same Wernicke's prophylaxis as chlordiazepoxide.
DO NOT discharge patient on clomethiazole if returning to environment with alcohol access.

Contraindications

Outpatient alcohol withdrawal (lethal with concurrent alcohol)
Severe respiratory depression
Severe pulmonary insufficiency
Acute alcohol intoxication
Concurrent alcohol consumption
Pregnancy and breastfeeding
Significant sleep apnoea

Side effects

Sedation, ataxia
Conjunctival irritation, sneezing, headache (very common — first-dose effect)
Respiratory depression (potentiated by alcohol)
Dependence (significant — historic concerns, less used now)
Hepatotoxicity
Falls in elderly
Hypotension, bradycardia (high doses or IV — IV preparation withdrawn UK)
Drug-induced lupus (rare)

Interactions

Alcohol: rapidly fatal respiratory depression — CONTRAINDICATED
Cimetidine: ↑ clomethiazole levels markedly
Other CNS depressants: additive
Carbamazepine: ↓ clomethiazole levels

Monitoring

Sedation score, respiratory rate hourly initially
BP
LFTs

Reference: BNF 90; SmPC Heminevrin; NICE CG115 (Alcohol-Use Disorders Management); BAP Substance Misuse Guidelines 2012. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Pathways