Flumazenil is a competitive GABAA receptor antagonist, used in the treatment of benzodiazepine overdoses.
Flumazenil interacts at the central benzodiazepine receptor to antagonize or reverse the behavioral, neurologic, and electrophysiologic effects of benzodiazepine agonists and inverse agonists. Flumazenil is of some benefit in hepatic encephalopathy, but until well-designed clinical trials are conducted, hepatic encephalopathy must be considered an investigational indication for flumazenil. Flumazenil has been shown to reverse sedation caused by intoxication with benzodiazepines alone or benzodiazepines in combination with other agents, but it should not be used when cyclic antidepressant intoxication is suspected[1]. Flumazenil (1 mg/kg) induces a strong anxiolytic effect in BALB/c mice tested in the elevated plus maze and light/dark test[2]. Flumazenil (10 mg/kg) effectively prevents the reduction produced by allopregnanolone in rats[3]. Flumazenil (5-20 mg/kg) antagonizes the anticonvulsant and adverse effects of diazepam but not GYKI 52466 in mice. Flumazenil slightly reduces the anticonvulsant activity of NBQX in the MES model but not in the PTZ test[4]. Flumazenil (3.0 mg/kg) blocks the changes withdrawal from chronic ethanol treatment, which leads to a decrease in open arm time and percent open arm entries[5].
Reference:
[1]. Hoffman EJ, et al. Flumazenil: a benzodiazepine antagonist. Clin Pharm. 1993 Sep;12(9):641-56; quiz 699-701.
[2]. Belzung C, et al. Flumazenil induces benzodiazepine partial agonist-like effects in BALB/c but not C57BL/6 mice. Psychopharmacology (Berl). 2000 Jan;148(1):24-32.
[3]. Fernandez-Guasti A, et al. Flumazenil blocks the anxiolytic action of allopregnanolone. Eur J Pharmacol. 1995 Jul 25;281(1):113-5.
[4]. Loscher W, et al. Effects of the non-NMDA antagonists NBQX and the 2,3-benzodiazepine GYKI 52466 on different seizure types in mice: comparison with diazepam and interactions with flumazenil. Br J Pharmacol. 1994 Dec;113(4):1349-57.
[5]. Moy SS, et al. Flumazenil blockade of anxiety following ethanol withdrawal in rats. Psychopharmacology (Berl). 1997 Jun;131(4):354-60.