Fipronil is an insecticide that acts as a selective antagonist of insect GABA receptors (IC50s = 30 and 1,600 nM for cockroach and rat receptors, respectively).1 It also inhibits desensitizing and non-desensitizing glutamate-induced chloride currents in cockroach neurons (IC50s = 800 and 10 nM, respectively). Fipronil induces activity of the cytochrome P450 (CYP) isoforms CYP1A1/2, CYP2B1/2, and CYP3A1/2 in isolated rat liver microsomes.2 Formulations containing fipronil have been used as insecticides in veterinary care.
1.Narahashi, T., Zhao, X., Ikeda, T., et al.Glutamate-activated chloride channels: Unique fipronil targets present in insects but not in mammalsPestic. Biochem. Physiol.97(2)149-152(2010) 2.Caballero, M.V., Ares, I., Martínez, M., et al.Fipronil induces CYP isoforms in ratsFood Chem. Toxicol.83215-221(2015)