Clomethiazole (1 mM), in the absence of GABA, to α1/β1/γ2 or α1/β2/γ2 subunit-containing cells produced large whole-cell currents. Clomethiazole activate GABAA currents in α1/β1/γ2- and α1/β2/γ2-containing cells, with EC ₅₀ values of 0.3 and 1.5 mM, respectively. Clomethiazole (30 μM) at low concentration also potentiates the action of GABA in both cell types, equivalent to a 3-fold increase in potency and up to 1.8-fold increase in maximal current. Clomethiazole inhibits cytochrome P450 isoforms, CYP2A6 and CYP2E1 with IC ₅₀ values of 24 µM and 42 µM, respectively, in human liver microsomes, meanwhile all other isoforms exhibiting values > 300 µM.