Benzodiazepine Antagonist Pregnancy: C — avoid; limited safety data

Flumazenil

Brand names: Anexate

Adult dose

Dose: 0.2mg IV, then 0.1mg every 60 sec

Route: IV

Frequency: Titrate to response

Max: 1mg (most patients respond to 0.3–0.6mg total)

Onset: 1–2 min. Duration: 45–90 min. If no response to 1mg total, benzodiazepine toxicity is unlikely to be the cause. ICU: 0.3mg IV for rapid reversal.

Clinical pearls

Duration (~45–90 min) is shorter than most benzodiazepines — re-sedation is common with long-acting drugs (diazepam, chlordiazepoxide). Observe minimum 2h after last dose.
NEVER use routinely in unknown or mixed overdose — risk of precipitating TCA-induced seizures or masking other CNS depressants.
Useful in: procedural sedation reversal (midazolam), accidental IV benzodiazepine overdose in non-dependent patients, or diagnostic use.
If seizure occurs after flumazenil: give IV benzodiazepine (midazolam 5mg IV), then propofol or barbiturate if refractory.

Contraindications

Chronic benzodiazepine dependence — precipitates acute withdrawal and seizures
Mixed overdose with tricyclic antidepressants — seizure risk after reversal
Raised intracranial pressure
Known seizure disorder managed with benzodiazepines
Suspected buprenorphine or alcohol overdose (no benefit)

Side effects

Seizures in benzodiazepine-dependent patients
Re-sedation when flumazenil wears off (45–90 min)
Nausea and vomiting
Anxiety, agitation, flushing

Interactions

Benzodiazepines: competitive antagonist at GABA-A receptor
Tricyclic antidepressants: risk of seizures after reversal
Z-drugs (zolpidem, zopiclone): partial reversal

Monitoring

Level of consciousness
respiratory rate
SpO₂ — reassess every 15 min for minimum 2h

Reference: NICE BNF 84; TOXBASE; NPIS Guidelines. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pathways

Benzodiazepine overdoseRecommended
TOXBASE/NPIS; AACT/EAPCCT; BNF

Same specialty