Fipronil is an insecticide that acts as a selective antagonist of insect GABA receptors. Fipronil also inhibits desensitizing and non-desensitizing glutamate-induced chloride currents in cockroach neurons . Fipronil induces activity of the cytochrome P450 (CYP) isoforms CYP1A1/2, CYP2B1/2, and CYP3A1/2 in isolated rat liver microsomes.