PRX-00023

PRX-00023 is a drug of the phenylpiperazine class that was being developed by EPIX Pharmaceuticals Inc for the treatment of generalized anxiety disorder and major depressive disorder. It was well tolerated in clinical trials but failed to reach significant remission on the Hammilton Rating Scales and development was subsequently discontinued.

PRX-00023 acts as a selective 5-HT1A receptor ligand and σ receptor agonist. Originally believed to have appreciable intrinsic activity as an agonist of the 5-HT1A receptor, later studies found it to possess very low efficacy (6-7% relative to 5-HT) and to behave more like an antagonist, likely underlying its failure as an antidepressant/anxiolytic in clinical trials.