Hexapradol was developed as a psychoanaleptic but was never marketed. Information about the current use of this drug is not available.

Sarizotan (also known as EMD-128,130), a chromane derivative that was developed as a selective 5-HT1A receptor agonist and D2 receptor antagonist. Experiments on animal models have shown that the drug effectively suppressed levodopa-induced dyskinesia in primate and rodent models of Parkinson's disease, and tardive dyskinesia in a rodent model. Sarizotan participated in phase II/III clinical trials in the treatment of dyskinesia associated with the dopaminergic treatment of Parkinson's disease. However, further development for this disease was discontinued by Merk, because phase III did not confirm earlier Phase II findings. On July 14, 2015, Newron Pharmaceuticals, research, and development company focused on the novel central nervous system (CNS) and pain therapies, announced that the U.S. Food and Drug Administration (FDA) has granted Orphan Drug Designation to sarizotan for treatment of Rett syndrome. Besides, the drug now is an ongoing clinical trial phase II/III to investigate its the tolerability and efficacy in reducing respiratory abnormalities in Rett Syndrome.

Enecadin (NS 7 or ZK 228326) is a voltage-dependent sodium and calcium channel blocker. Enecadin is a neuroprotective agent demonstrated efficacy in animal models of ischemic injury of brain, spinal cord and retina. Enecadin was undergoing phase II development in stroke with PAION in Germany. Enecadin development has been discontinued.

Radafaxine (GW353162, ( )-(2S,3S)-2-(3-chlorophenyl-3,5,5-trimethyl-2-morphinol) or S,S-hydroxybupropion) is an active metabolite of bupropion. It acts as an inhibitor of the dopamine transporter. Radafaxine was investigated for the treatment of depression however, development was discontinued.

Aplindore (DAB-452) is a small molecule that displays potent dopamine D2 receptor partial agonist activity in in vitro and in vivo assays and is predicted to have antipsychotic efficacy without motor side effects. Aplindore had been in phase II clinical trials for the treatment of Parkinson's disease and restless legs syndrome. Aplindore was generally well tolerated and there were no withdrawals due to adverse events and no serious adverse events.

Talisomycin (former trivial name: tallysomycin A), a third generation bleomycin analog that was studied as an antitumor antibiotic. The drug cleaved DNA preferentially at G-C and G-T sequences and produced specific cleavages at G-A sequences. Talisomycin participated in phase II clinical trial for the treatment of cancer; however, the further development of the drug was discontinued.

Cliropamine (D 16427) is a positive inotropic compound.

Millennium Pharmaceuticals Inc's tandutinib (MLN-518), a piperazinyl derivative of quinazoline, is an orally active inhibitor of FLT3 kinase and family members PDGFR beta and c-Kit. Tandutinib inhibited FLT3 phosphorylation, downstream signaling and malignant growth in vitro and in animal models. The drug exhibited limited activity as a single agent in phase I and II clinical trials in patients with AML and myelodysplastic syndrome, but displayed promising antileukemic activity (90% complete remissions) in a phase I/II trial in patients with newly diagnosed AML when administered in combination with cytarabine and daunorubicin. Phase II clinical trials for tandutinib in patients with Glioblastoma have being discontinued. The use of tandutinib to treat AML has been granted fast-track status by the U.S. Food and Drug Administration. Phase II trials were underway., but later withwrawn.

Talnetant (SB-223412) is a selective, orally active neurokinin 3 receptor antagonist and is under development for the potential treatment of several disorders, including irritable bowel syndrome, schizophrenia, chronic obstructive pulmonary disease, cough, overactive bladder and urinary incontinence. The most common adverse effects were headache, fatigue, and nausea.

Tarazepide is a cholecystokinin-A receptor (CCK-A) receptor antagonist that was studied as an antispasmodic agent. However, information about the current use of this drug is not available.