Tilapertin (also known as AMG 747) is a piperazineacetic acid derivative patented by Amgen Inc as glycine transporter-1 inhibitor useful for the treatment of negative symptoms of schizophrenia. Oral administration of AMG 747 dose-dependently increases cerebrospinal fluid(CSF) glycine concentration in rats. In humans, Tilapertin has linear pharmacokinetics, prolonged half-life, and acceptable safety and tolerability at multiple doses up to 60 mg daily dosing. Unfortunately, in clinical trials, Tilapertin failed to demonstrate superior efficacy compare antipsychotic therapy in clinically stable people with schizophrenia.