Benzodiazepine — Short-acting Pregnancy: Avoid — benzodiazepines cause neonatal respiratory depression, hypotonia, and withdrawal. For acute life-threatening status epilepticus: benefit outweighs risk; use minimum effective dose.

Lorazepam (Psychiatric/Acute Use)

Brand names: Ativan

Adult dose

Dose: Acute anxiety / agitation: 0.5–2mg oral or IM; repeat after 30–60 minutes if needed (max 4mg in 24h). Status epilepticus (IV): 4mg IV bolus; repeat once after 10 minutes if seizure continues. Procedural sedation: 1–2.5mg IV.

Route: Oral / IM / IV

Frequency: As required (not for regular use — short-term only)

Max: 4mg IV (status epilepticus); 4mg per 24h (acute agitation)

Preferred benzodiazepine for acute psychiatric agitation — reliable IM absorption (unlike diazepam IM which is poorly and erratically absorbed). No active metabolites — shorter, predictable duration (6–8h). Also first-line IV benzodiazepine for status epilepticus (NICE CG137). Maximum 2–4 weeks continuous use — dependence risk.

Paediatric dose

Dose: 0.1 mg/kg

Route: IV / IM / Oral

Frequency: Single dose (status epilepticus); as required (anxiety)

Max: 4mg IV (status epilepticus)

BNFc: Status epilepticus: 100 micrograms/kg IV (max 4mg); repeat once after 10 minutes. Neonates: 100 micrograms/kg IV. Anxiety: seek specialist child and adolescent psychiatry opinion.

Dose adjustments

Renal

Use with caution in severe renal impairment — accumulation of inactive glucuronide metabolites.

Hepatic

Preferred benzodiazepine in hepatic impairment — undergoes direct glucuronidation (no hepatic CYP450 metabolism), unlike diazepam.

Paediatric weight-based calculator

Patient weight (kg)

BNFc: Status epilepticus: 100 micrograms/kg IV (max 4mg); repeat once after 10 minutes. Neonates: 100 micrograms/kg IV. Anxiety: seek specialist child and adolescent psychiatry opinion.

Clinical pearls

CRITICAL clozapine interaction: severe cardiorespiratory collapse and deaths reported with combination of IM clozapine and IV benzodiazepines — do not use IV lorazepam if patient has received IM clozapine within 1 hour (MHRA warning)
Antidote: flumazenil 200 micrograms IV, then 100 micrograms every 60 seconds (max 1mg total) — reverses sedation but not respiratory depression fully; short duration (repeat dosing may be needed; half-life shorter than most BDZs)
IM lorazepam preferred over IM diazepam — diazepam is poorly absorbed IM due to precipitation in muscle; lorazepam has reliable IM absorption
Preferred BDZ in hepatic impairment (no CYP metabolism) and in elderly (no active metabolites unlike diazepam which has very long-acting metabolites)

Contraindications

Respiratory failure / COPD (unless intubated)
Myasthenia gravis
Sleep apnoea syndrome
Acute narrow-angle glaucoma
Hypersensitivity to benzodiazepines

Side effects

Sedation, CNS depression
Respiratory depression (dose-dependent — particularly IV at speed)
Anterograde amnesia
Paradoxical agitation (especially in elderly and children)
Dependence and withdrawal (even after short courses)
Hypotension (IV)
Thrombophlebitis (IV — use peripheral dilution)

Interactions

CNS depressants (opioids, alcohol, antipsychotics, antihistamines) — additive sedation and respiratory depression
Clozapine — IV benzodiazepines reported to cause cardiac arrest in clozapine-treated patients — do not give IV lorazepam within 1 hour of IM clozapine
Valproate — displaces lorazepam from protein binding — increased free lorazepam levels

Monitoring

Respiratory rate and oxygen saturation (IV use)
Level of consciousness
Dependence risk assessment (review regularly if prescribed)
Paradoxical agitation (particularly in elderly)

Reference: BNFc; BNF 90; NICE CG137 (Epilepsies); NICE NG10 (Violence and Aggression); MHRA Clozapine Safety. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

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