Flumazenil

Flumazenil (also known as flumazepil, code name Ro 15-1788, trade names Anexate, Lanexat, Mazicon, Romazicon) is a benzodiazepine antagonist, used as an antidote in the treatment of benzodiazepine overdose. It reverses the effects of benzodiazepines by competitive inhibition at the benzodiazepine binding site on the GABAA receptor. It was introduced in 1987 by Hoffmann-La Roche under the trade name Anexate.

The onset of action is rapid and usually effects are seen within one to two minutes. The peak effect is seen at six to ten minutes. The recommended dose for adults is 200 μg every 1-2 minutes until the effect is seen, to a maximum of 3 mg per hour. It is available as a clear, colourless solution for intravenous injection, containing 500 μg in 5 mls.

All benzodiazepines (including midazolam) have longer half-lives than flumazenil. Therefore, repeat doses of flumazenil may be required to prevent recurrent symptoms of overdosage once the initial dose of flumazenil wears off. It is hepatically metabolised to inactive compounds which are excreted in the urine. Subjects who are physically dependent on benzodiazepines may suffer benzodiazepine withdrawal symptoms, including seizure, upon administration of flumazenil.