Pharmacology Notes

Flumazenil is a competitive antagonist at benzodiazepine receptors in the central nervous system. Administration results in reversal of the CNS depressant effects of benzodiazepines. It has a duration of action of approximately 45 to 60 minutes, after which time re-sedation may occur, as most benzodiazepines have much longer durations of action. Therefore, patients must be observed for several hours after a dose of flumazenil.

Flumazenil should not be given routinely to all patients presenting with coma or altered conscious states of uncertain aetiology, due to concern about the precipitation of seizures in patients with epilepsy, chronic benzodiazepine use, unrecognised tricyclic antidepressant co-ingestion or ingestion of other proconvulsant drugs. It may be used to avoid intubation in cases where these concerns can be specifically and reliably excluded. Flumazenil should only be administered in a setting able to manage seizures.

Flumazenil is generally administered in small incremental doses. If no response is seen after administration of a cumulative dose of 2 mg, other causes of CNS depression should be sought. Flumazenil has been administered as a continuous infusion.