Fipronil

Fipronil is a broad-spectrum insecticide effective against Lepidoptera species as well as thrips, locusts, ants, cockroaches, fleas and ticks. Fipronil selectively inhibits GABA receptor with IC₅₀s of 30 nM and 1600 nM for cockroach and rat GABA receptors, respectively. Glutamate-gated chloride channels (GluCls), which are present in cockroaches but not in mammals, are sensitive to the blocking effect of Fipronil. Fipronil also induces apoptosis in HepG2 cells and promotes the expression of CYP1A1 and CYP3A4 mRNA in human hepatocytes^[1][2]. In Vitro:Fipronil (0.1-25 µM; 72 h) dose-dependently induces expression of CYP1A1 and CYP3A4 mRNA in human hepatocytes^[1].
Fipronil (0.1-25 µM; 72 h) induces caspase-3/7 activity in a time- and dose-dependent manner, in HepG2 cells (caspase-3/7 activity is an important marker of the cellular apoptotic process)^[1]. In Vivo:Fipronil inhibits two types of glutamate-induced chloride desensitizing and non-desensitizing current with IC₅₀ values of 800 and 10 nM, respectively^[2].
Fipronil is more selective for cockroach GABA receptors than for rat GABA^[2].
Fipronil blocks cockroach GABA receptors in both resting and activated states, with IC₅₀s of 28 and 35 nM, respectively^[2].