Taziprinone was studied as an antitussive agent. Information about the current use of this compound is not available.

Stacofylline is a xanthine derivative patented by ADIR for the treatment of migraine and asthenia.

Danegaptide (GAP-134) is a small dipeptide gap junction modifier, developed by Wyeth and Zealand Pharma. Danegaptide works by re-establishing of gap junction intercellular communications in adjacent cardiomyocytes, thus reversing cardiac conduction slowing and electrical heterogeneity thought to be responsible for arrhythmias. In a canine model of acute sterile pericarditis, Danegaptide significantly reduced AF duration and overall AF burden. Danegaptide was investigated in phase 2 clinical trial in patients with ST-segment elevation myocardial infarction (STEMI). It was found that administrations danegaptide to patients with STEMI did not improve myocardial salvage, and development of the drug was discontinued.

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.