5-Methoxytryptamine (aka 5-MT, mexamine) is a tryptamine derivative closely related to the neurotransmitters serotonin and melatonin. 5-MT is produced endogenously at low levels; it is biosynthesized by deacetylation of melatonin in the pineal gland. 5-MT acts as a full agonist at the 5-HT1, 5-HT2, 5-HT4, 5-HT6, and 5-HT7 receptors. It is often used as a chemical probe in the study of serotonin receptors, but it has also been used in a clinical trial to mitigate the anemic effects of cisplatin chemotherapy.

Ameltolide (ADD 75073, LY 201116) is a 4-aminobenzamide anticonvulsant patented by Research Corporation Technologies in the USA. Ameltolide is a sodium channel antagonist, it represents a potential therapy for the treatment of epilepsy. Ameltolide had been in phase I clinical trials by Research Corporation Technologies for the treatment of epilepsy. However, this research has been discontinued.

Bisphenol A is a small estrogenic monomer that is polymerized to produce polycarbonate plastic and resins used to line metal cans. It is also used to make some dental sealants. Bisphenol A had been considered to be a very weak environmental estrogen. It is able to interact with human estrogen receptors. In addition, it binds strongly to the estrogen-related receptor gamma. Bisphenol A inhibited androgen-induced androgen receptor transcriptional activity. Prenatal exposure to maternal Bisphenol A concentrations were related to higher levels of anxiety, depression, aggression, and hyperactivity in children. Bisphenol A exposure in childhood was associated with higher levels of anxiety, depression, hyperactivity, inattention, and conduct problems. It never found use as a drug.

Metaclazepam is a benzodiazepine derivative. It exerts anxiolytic properties.

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

Ifoxetine was developed as an unusual drug that specifically and selectively blocks the 5-HT reuptake in the brain without affecting the 5-HT uptake processes in the periphery (blood platelets). The drug was undergoing phase II clinical trials for the treatment of depression; however, the study was suspended.

Igmesine is a sigma-1 receptor agonist. It was assayed in clinical trials targeting major depressive disorder. Igmesine is the only antisecretory agent that we have tested to date that inhibits both cholera toxin and the E. coli enterotoxins. Sigma receptors are known to be present on nerves in the enteric nervous system and this would seem to be a potentially useful class of drugs to pursue for the treatment of secretory diarrhoea in humans. It was shown that when Alzheimer's disease rats were submitted to the conditioned fear stress test, igmesine can significantly reduce the stress-induced motor suppression, indicating exogenous σ-1 receptor agonists may alleviate Alzheimer's disease-associated depressive symptoms.

Temperocol is an investigative anti-cancer drug that inhibits the expression of survivin and CDK-1; discovered at Johns Hopkins University and under development by Erimos Pharmaceuticals. It has been tested in phase I/II clinical trials for Leukemia, and several forms of neoplasms including gliomas. Results of these clinical trials have shown promise, however treatment regimes produce several toxic side effects that need to be balanced against efficacy. Temperocol is a fully methylated derivative of the natural product Nordihydroguaiaretic acid.

MK-3207 represents the third CGRP receptor antagonist to display clinical efficacy in migraine trials. It is a potent CGRP receptor antagonist with IC50 and Ki of 0.12 nM and 0.022 nM, highly selective versus human AM1, AM2, CTR, and AMY3. MK-3207 had been in phase II clinical trials by Merck Sharp & Dohme for the treatment of migraine. But the company had discontinued the research due to asymptomatic liver test abnormalities in 2010.

Becampanel (AMP397) is an aminomethylquinoxalinedione AMPA receptor antagonist. Also, AMP397 demonstrates binding to hydroxyapatite. AMP397 has no genotoxic potential in vivo. In particular, no genotoxic metabolite is formed in mammalian cells, and, if formed by intestinal bacteria, is unable to exert any genotoxic activity in the adjacent intestinal tissue. AMP397 has a significant oral bioavailability of 22% in mice and approximately 50% in humans. It was under development for the potential treatment of status epilepticus and other types of seizures. However, this research has been discontinued. It is also being evaluated for use in the treatment of neuropathic pain and cerebrovascular ischemia.