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Benzodiazepine — Long-acting Pregnancy: Avoid — fetal benzodiazepine syndrome (hypotonia, respiratory depression, withdrawal). If used near delivery: monitor neonate for days due to long half-life.

Clonazepam (Psychiatric Use)

Brand names: Rivotril

Adult dose

Dose: Panic disorder / anxiety (short-term adjunct): 0.5mg BD initially; increase by 0.5mg every 3 days to a maximum of 4mg daily. Bipolar disorder (acute mania adjunct): 1–2mg BD–TDS short-term. Epilepsy (myoclonic, absence): 0.5mg OD at night initially, increase to 4–8mg daily in divided doses.
Route: Oral
Frequency: Twice to three times daily
Max: 20mg daily (epilepsy — specialist only); 4mg daily (psychiatric indications)
Long-acting benzodiazepine (half-life 20–60h). Used short-term in psychiatry as an adjunct for acute mania (while mood stabiliser takes effect) or panic disorder. Significant dependence potential — limit to 2–4 weeks in psychiatric indications. Abrupt withdrawal after prolonged use can cause seizures — taper very slowly.

Paediatric dose

Dose: 0.01 mg/kg
Route: Oral
Frequency: Once to three times daily
Max: 0.05mg/kg/day (epilepsy)
BNFc: Epilepsy: 1 month–11 years: 10 micrograms/kg BD initially (max 500 micrograms BD); 12–17 years: 500 micrograms BD initially. Psychiatric use in children: seek specialist child and adolescent psychiatry opinion.

Dose adjustments

Renal

Use with caution — enhanced sedation in renal impairment.

Hepatic

Avoid in severe hepatic impairment — accumulation risk (long half-life and hepatic metabolism).

Paediatric weight-based calculator

BNFc: Epilepsy: 1 month–11 years: 10 micrograms/kg BD initially (max 500 micrograms BD); 12–17 years: 500 micrograms BD initially. Psychiatric use in children: seek specialist child and adolescent psychiatry opinion.

Clinical pearls

  • Antidote: flumazenil 200 micrograms IV then 100 micrograms every 60 seconds (max 1mg) — note: flumazenil has a shorter half-life than clonazepam; repeated doses or infusion may be needed
  • Withdrawal: long half-life means withdrawal symptoms are delayed (days after stopping) but withdrawal seizures can occur — taper over weeks to months for long-term users
  • Paradoxical disinhibition: may worsen behaviour in borderline personality disorder — use with great caution in personality disorders; can precipitate rage or self-harm
  • Not for long-term use in psychiatry — dependence develops rapidly; NICE recommends maximum 2–4 weeks for anxiety indications

Contraindications

  • Respiratory failure
  • Myasthenia gravis
  • Sleep apnoea
  • Acute angle-closure glaucoma
  • Severe hepatic impairment
  • Hypersensitivity to benzodiazepines

Side effects

  • Sedation, cognitive impairment
  • Ataxia, dizziness
  • Behavioural disinhibition
  • Dependence and withdrawal (severe — seizures on abrupt withdrawal)
  • Paradoxical aggression (especially in personality disorders)
  • Respiratory depression (particularly with opioids)

Interactions

  • CNS depressants, opioids, alcohol — additive respiratory depression
  • Valproate (with clonazepam in absence epilepsy) — may precipitate absence status — use with caution
  • CYP3A4 inhibitors — increase clonazepam levels

Monitoring

  • Dependence risk (review weekly in short-term use)
  • Respiratory function
  • Cognitive function (long-term — impairs memory)
  • Withdrawal symptoms on dose reduction

Reference: BNFc; BNF 90; NICE CG185 (Bipolar Disorder); NICE CG22 (Anxiety). Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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