Methylenedioxymethamphetamine (or 3,4-methylenedioxymethamphetamine (MDMA)), a synthetic, psychoactive drug also known as ecstasy that was used as a recreational drug. This drug acts as both a stimulant and psychedelic and exerts its effects in the brain on neurons that use the chemicals serotonin, dopamine and norepinephrine to communicate with other neurons. In spite of the presence of this compound in the List of control and forbidden compounds, it was studied in psychotherapy for patients with chronic, treatment-resistant posttraumatic stress disorder. Initial results showed efficacy for the treatment approach, although further studies are needed.

Naronapride (ATI-7505), an orally administered, cisapride analogue and serotonin4 (5HT4) receptor agonist, is being developed by Renexxion for the treatment of multiple gastrointestinal disorders. Sinovant is initially developing naronapride for the treatment of irritable bowel syndrome – constipation (IBS-C), a disease that affects millions of Chinese patients and for which few effective treatment options are available. Naronapride has been evaluated in over 900 subjects in multiple randomized controlled clinical studies and has demonstrated promising results in patients with gastroesophageal reflux disease (GERD), erosive esophagitis (EE), and chronic idiopathic constipation (CIC). Naronapride’s low systemic absorption and high specificity for 5HT4 and D2 receptors is thought to improve its safety and tolerability profile relative to other members of the class.

Elopiprazole [DU 29894 or 1-(7-benzofuranyl)-4-[[5-(4-fluorophenyl)-1-H-pyrrol-2yl]methyl]piperazine) is an antagonist at dopamine D2 and D3 receptors and an agonist at serotonin1A receptors. Elopiprazole development for the treatment of psychotic disorders has been discontinued.

Lysergide (LSD) is a semi-synthetic hallucinogen and is one of the most potent drugs known. Recreational use became popular between the 1960s to 1980s, but is now less common. LSD was first synthesized by Albert Hoffman while working for Sandoz Laboratories in Basel in 1938. Some years later, during a re-evaluation of the compound, he accidentally ingested a small amount and described the first ‘trip’. During the 1950s and 1960s, Sandoz evaluated the drug for therapeutic purposes and marketed it under the name Delysid®. It was used for research into the chemical origins of mental illness. Recreational use started in the 1960s and is associated with the ‘psychedelic period’. LSD possesses a complex pharmacological profile that includes direct activation of serotonin, dopamine and norepinephrine receptors. In addition, one of its chief sites of action is that of compound-specific (“allosteric”) alterations in secondary messengers associated with 5HT2A and 5HT2C receptor activation and changes in gene expression. The hallucinogenic effects of LSD are likely due to agonism at 5HT2A and 5HT2C receptors. LSD is also an agonist at the majority of known serotonin receptors, including 5HT1A, 5HT1B, 5HT1D, 5HT5A, 5HT6 and 5HT7 receptors. During the 1960s, LSD was investigated for a variety of psychiatric indications, including the following: as an aid in treatment of schizophrenia; as a means of creating a "model psychosis"; as a direct antidepressant; and as an adjunct to psychotherapy. LSD is listed in Schedule I of the United Nations 1971 Convention on Psychotropic Substances.

Sumanirole is a novel dopamine agonist with high affinity and efficacy at D2 dopamine receptors and has a substantial degree of selectivity for the D2 receptor over other dopamine receptor subtypes. It had been in clinical trials for the treatment of Parkinson’s disease and restless leg syndrome but these studies were terminated for the efficacy reason.