GABA receptor antagonists are drugs that  inhibit the action of GABA. In general these drugs produce stimulant and convulsant effects, and are mainly used for counteracting overdoses of sedative drugs.
Examples include bicuculline, securinine and metrazol, and the benzodiazepine GABA receptor antagonist flumazenil.
Other agents which may have GABA receptor antagonism include the antibiotic ciprofloxacin, tranexamic acid, thujone, ginkgo biloba, and kudzu.