Sunepitron (CP-93,393) is an anxiolytic drug with highly selective serotonin 5-hydroxytryptamine 1A autoreceptor agonist, alpha2-adrenergic antagonist, and dopamine D2 agonist properties. Sunepitron hydrochloride had been in Phase III clinical trials by Pfizer for the treatment of anxiety disorder and depression. However, this research has been discontinued.

Pardoprunox is a partial D2/3 dopamine receptor agonist and full 5-HT1A serotonin receptor agonist. Partial D(2/3) dopamine (DA) receptor agonists provide a novel approach to the treatment of the motor symptoms of Parkinson's disease that may avoid common dopaminergic side effects, including dyskinesia and psychosis. Pardoprunox passed phase III clinical trial for the treatment of Parkinson's disease.

Osemozotan (also known as MKC-242) was developed as a selective 5-HT1A receptor agonist. Experiments on animal have shown that osemozotan improved most abnormal behaviors such as isolation rearing. Osemozotan was being investigated for the treatment of pain, aggressive behavior, anxiety, depression, obsessive-compulsive disorder, and drug dependence with methamphetamine and cocaine. However, all these studies were suspended. In the USA osemozotan participated in phase II clinical trial for the insomnia patients, however, the study was terminated because of the license agreement.

IPSAPIRONE, an azapirone derivative structurally unrelated to the benzodiazepines, is a selective 5-HT1A serotonin receptor agonist. It has antidepressant and anxiolytic effects. IPSAPIRONE was studied in several clinical trials for depression and generalized anxiety disorder.

Bifeprunox, code name DU-127,090 is an atypical antipsychotic agent, which combines minimal D2 receptor agonism with 5-HT receptor agonism. Bifeprunox was in phase III of clinical trials for the treatment of schizophrenia, Bipolar Depression and in phase I for Parkinson's disease, but these studies were discontinued because efficacy data did not support pursuing the existing development strategy of stabilization of non-acute patients with schizophrenia.

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.

Mazapertine (RWJ-37796) is an arylpiperazine antipsychotic with high affinity to dopamine D2 and D3, serotonin 5-HT1A and alpha 1A-adrenergic receptors. It was being studied in the treatment of schizophrenia.

FLESINOXAN, a phenylpiperazine derivative, is a selective agonist for 5-HT1A receptors. It is an antidepressant agent which clinical development was stopped.

Tiospirone (TSP) is an atypical antipsychotic drug. Tiaspirone appeared to be a promising antipsychotic agent as it didn`t cause extrapyramidal syndromes. It has 5HT-2 antagonistic properties as well as affinity for D2, 5HT-1a, 5HT-6 and sigma receptors. Tiospirone was in phase III clinical trials for the treatment of attention hyperactivity disorder with Mead Johnson in the USA but its development appears to have been discontinued.