MK0343 (MRK-409) is an orally bioavailable GABA_A receptor subtype-selective partial agonist. MK0343 is a non-sedating anxiolytic^[1]. IC50 & Target: Ki: 0.22 nM (rGABA_A α1), 0.4 nM (rGABA_Aα2) , 0.21 nM (rGABA_Aα3), 78 nM (rGABA_Aα4), 0.23 nM (rGABA_Aα5), 980 nM (rGABA_Aα6)^[1] In Vivo: MK0343 readily penetrates the brain in rats and occupies the benzodiazepine site of GABAA receptors, measured using an in vivo [³H]flumazenil binding assay, with an Occ₅₀ of 2.2 mg/kg p.o. and a corresponding plasma EC₅₀ of 115 ng/mL^[1].