4‐Chlorokynurenine (AV-101) is a neuropharmaceutical drug candidate in development for the treatment of major depressive disorder. Pharmacology studies conducted in rodent models have demonstrated AV-101’s antihyperalgesic activity in models of facilitated pain processing was seen at serum concentrations ranging from 150–300 M. In addition, AV-101 has been shown to be neuroprotective activity against an intrahippocampal injection of quinolinic acid, reductions in seizures, and antidepressive activity. An oral prodrug, AV-101, which, in the brain, is converted into one of the most potent and selective GlyB site antagonists of the NMDAR, has been demonstrated to be active in animal models of neuropathic pain. The two Phase 1 studies were designed to assess the safety and pharmacokinetics of AV-101, over a wide dose range, after daily dosing for 14-days. AV-101 has excellent safety and PK characteristics providing support for advancing AV-101 into Phase 2 studies in neuropathic pain.