U93631 is a GABAA receptor ligand of novel chemical structure with IC50 of 100 nM,and has been shown to induce a rapid, time-dependent decay of GABA-induced whole-cell Cl-currents in recombinant GABAA receptors. target: GABAA receptor IC 50: GABAA receptor[1] In vitro: In the presence of U93631 at 5 UM, the peak amplitude decreased as a function of GABA concentration, with the half-maximal inhibitory concentration being approximately 100 nM, which is close to the Kd for the high affinity GABA site(85 nM). It appears that the drug interacts with GABA-bound receptors (at least monoliganded) and accelerates receptor desensitization, rather than acting as an open channel blocker. [1]