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.

Mitoflaxone, also known as flavone acetic acid is a synthetic flavonoid that has been studied as an antitumor agent. Mitoflaxone was involved in phase II clinical trials in Europe for patients with advanced colorectal carcinoma and for patients with advanced malignant melanoma. Despite the promising preclinical activity, this drug didn’t demonstrate any clinical activity. Further studies of the drug were suspended.

Pelrinone, a cardiotonic drug, is a phosphodiesterase III inhibitor that was studied in clinical trials phase II for the treatment of patients with heart failure.

Cemadotin (LU103793) is a cytotoxic water-soluble pentapeptide analogue of dolastatin 15. The dolastatin peptides were originally isolated from the shell-less mollusc Dolabella auricularia. Cemadotin blocks cells at mitosis. It exerts its antitumor activity by suppressing spindle microtubule dynamics through a distinct molecular mechanism by binding at a novel site in tubulin. Cemadotin was in phase II clinical trials as a promising cancer chemotherapeutic agent. However, this agent appears to be inactive in the treatment of advanced non-small-cell lung cancer and other tumors and this research has been discontinued.

Fasobegron is an agonist of β3-adrenoreceptor.

Vabicaserin is a 5-hydroxytryptamine 2C (5-HT2C) receptor-selective agonist with an EC50 of 8 nM. Pfizer was developing vabicaserin, an oral serotonin (5-HT)2C receptor agonist, for the treatment of schizophrenia and bipolar disorder. Vabicaserin decreases nucleus accumbens extracellular dopamine levels in rats, without affecting striatal dopamine, indicating mesolimbic selectivity. Vabicaserin had been in phase II clinical trials for the treatment of schizophrenia. However, research of Vabicaserin for the treatment schizophrenia and obesity was discontinued.

Ruzadolane (previously known as UP 26-91) is a serotonin receptor antagonist that was developed as a non-narcotic, centrally acting analgesic agent for the treatment of anxiety disorder and pain. However, these studies were discontinued.

FLOPRISTIN is one of the components of the experimental drug NXL103 (XRP 2868), along with linopristin. Both are semi-synthetic streptogramin antibiotics derived from the Streptomyces genus. NXL103 has a spectrum of antibacterial activity that indicates it has the potential to be effective in the treatment of skin and skin structure infections, including those caused by methicillin-resistant Staphylococcus aureus, as well as community-acquired pneumonia. NXL103 has completed Phase II trials.

Esmirtazapine (S-(+)mirtazapine or ORG-50081) is an enantiomer of mirtazapine (REMERON®), a high-affinity antagonist at 5-HT2/5-HT3 and H1 receptors, used in the treatment of depression. Esmirtazapine has a shorter plasma half-life than the R(−) enantiomer. Esmirtazapine is preferentially metabolized into an 8-hydroxy glucuronide. Organon was developing esmirtazapine for the treatment of hot flushes (vasomotor symptoms) associated with the menopause and insomnia.

Clostebol is a synthetic anabolic-androgenic steroid, a derivative of the natural hormone testosterone. Clostebol is a Schedule III controlled substance used medically in topical ophthalmologic and dermatologic treatments. Due to potential use as a performance-enhancing drug, clostebol is banned by the World Anti-Doping Agency.