Ritanserin, also known by its developmental code name R-55667, is a serotonin antagonist medication described as an anxiolytic, antidepressant, antiparkinsonian agent, and antihypertensive agent. It was never marketed for medical use due to safety problems but has been used in scientific research to study the serotonin system.
Clorgiline (INN), or clorgyline (BAN), is a monoamine oxidase inhibitor (MAOI) structurally related to pargyline which is described as an antidepressant. Specifically, it is an irreversible and selective inhibitor of monoamine oxidase A (MAO-A). Clorgiline was never marketed, but it has found use in scientific research. It has been found to bind with high affinity to the σ1 receptor (Ki = 3.2 nM) and with very high affinity to the I2 imidazoline receptor (Ki = 40 pM).
Chlorotrianisene (CTA), also known as tri-p-anisylchloroethylene (TACE) and sold under the brand name Tace among others, is a nonsteroidal estrogen related to diethylstilbestrol (DES) which was previously used in the treatment of menopausal symptoms and estrogen deficiency in women and prostate cancer in men, among other indications, but has since been discontinued and is now no longer available. It is taken by mouth.
Pipamperone, also known as carpiperone and floropipamide or fluoropipamide, and as floropipamide hydrochloride (JAN), is a typical antipsychotic of the butyrophenone family used in the treatment of schizophrenia and as a sleep aid for depression. It is or has been marketed under brand names including Dipiperon, Dipiperal, Piperonil, Piperonyl, and Propitan. Pipamperone was discovered at Janssen Pharmaceutica in 1961, and entered clinical trials in the United States in 1963.
Mibolerone, also known as dimethylnortestosterone (DMNT) and sold under the brand names Cheque Drops and Matenon, is a synthetic, orally active, and extremely potent anabolic–androgenic steroid (AAS) and a 17α-alkylated nandrolone (19-nortestosterone) derivative which was marketed by Upjohn for use as a veterinary drug. It was indicated specifically as an oral treatment for prevention of estrus (heat) in adult female dogs.
Metopimazine, sold under the brand names Nortrip, Vogalen, and Vogalene, is an antiemetic of the phenothiazine group which is used to treat nausea and vomiting. It is marketed in Europe, Canada, and South America. As of August 2020, metopimazine has been repurposed and is additionally under development for use in the United States for the treatment of gastroparesis.
Enclomifene (INN), or enclomiphene (USAN), is a nonsteroidal selective estrogen receptor modulator of the triphenylethylene group which was under development for the treatment of male hypogonadism and type 2 diabetes. By December 2016, it was in preregistration and was under review by the Food and Drug Administration in the United States and the European Medicines Agency in the European Union. In January 2018, the Committee for Medicinal Products for Human Use of the European Medicines Agency recommended refusal of marketing authorization for enclomifene for the treatment of secondary hypogonadism. In April 2021, development of enclomifene was discontinued for all indications.
Zuclomifene is a nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that was never marketed. It is one of the two stereoisomers of clomifene, which itself is a mixture of 38% zuclomifene and 62% enclomifene. Zuclomifene is the (Z)-stereoisomer of clomifene, while enclomifene is the (E)-stereoisomer. Whereas zuclomifene is described as mildly estrogenic, enclomifene is described as antiestrogenic. In accordance, unlike enclomifene, zuclomifene is antigonadotropic due to activation of the estrogen receptor and reduces testosterone levels in men. It is also about five times more potent than enclomifene in inducing ovulation.
Metitepine, also known as methiothepin, is a drug described as a "psychotropic agent" of the tricyclic group which was never marketed. It acts as a non-selective antagonist of serotonin, dopamine, and adrenergic receptors and has antipsychotic properties.
Mesulergine (INN) (developmental code name CU-32085) is a drug of the ergoline group which was never marketed. It acts on serotonin and dopamine receptors. Specifically, it is an agonist of dopamine D2-like receptors and serotonin 5-HT6 receptors and an antagonist of serotonin 5-HT2A, 5-HT2B, 5-HT2C, and 5-HT7 receptors. It also has affinity for the 5-HT1A, 5-HT1B, 5-HT1D, 5-HT1F, and 5-HT5A receptors. The compound had entered clinical trials for the treatment of Parkinson's disease; however, further development was halted due to adverse histological abnormalities in rats. It was also investigated for the treatment of hyperprolactinemia (high prolactin levels).
Cyclofenil, sold under the brand name Sexovid among others, is a selective estrogen receptor modulator (SERM) medication which is used as a gonadotropin stimulant or ovulation inducer and in menopausal hormone therapy in women. It is mostly no longer available. The medication is taken by mouth.
Trioxifene (INN), or as the salt trioxifene mesylate (USAN), is a selective estrogen receptor modulator (SERM) with competitive binding activity against estradiol for the ERα and antagonistic activity against ERα-mediated gene expression, that was under preclinical and clinical development by Eli Lilly and Company for breast cancer and prostate cancer, but was abandoned. Its affinity for the rat estrogen receptor was reported to be 20% relative to estradiol.
Delmadinone acetate (DMA), sold under the brand name Tardak among others, is a progestin and antiandrogen which is used in veterinary medicine to treat androgen-dependent conditions such as benign prostatic hyperplasia. It must be used with care as it has the potential to cause adrenal insufficiency via inhibition of adrenocorticotropic hormone (ACTH) secretion from the pituitary gland. DMA is the C17α acetate ester of delmadinone, which, in contrast to DMA, was never marketed for medical use.
Broparestrol (INN), also known as α-bromo-α,β-diphenyl-β-p-ethylphenylethylene (BDPE), is a synthetic, nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that has been used in Europe as a dermatological agent and for the treatment of breast cancer. The drug is described as slightly estrogenic and potently antiestrogenic, and inhibits mammary gland development and suppresses prolactin levels in animals. It is structurally related to clomifene and diethylstilbestrol. Broparestrol is a mixture of E- and Z- isomers, both of which are active and are similarly antiestrogenic but, unlike broparestrol, were never marketed.
Flumexadol (INN) is a drug described and researched as a non-opioid analgesic which was never marketed. It has been found to act as an agonist of the serotonin 5-HT1A and 5-HT2C receptors and, to a much lesser extent, of the 5-HT2A receptor. According to Nilsson (2006) in a paper on 5-HT2C receptor agonists as potential anorectics, "The (+)-enantiomer of this compound showed [...] affinity for the 5-HT2C receptor (Ki) 25 nM) [...] and was 40-fold selective over the 5-HT2A receptor in receptor binding studies. Curiously, the racemic version [...], also known as 1841 CERM, was originally reported to possess analgesic properties while no association with 5-HT2C receptor activity was mentioned." It is implied that flumexadol might be employable as an anorectic in addition to analgesic. Though flumexadol itself has never been approved for medical use, oxaflozane is a prodrug of the compound that was formerly used clinically in France as an antidepressant and anxiolytic agent.
Triphenylbromoethylene, also known as bromotriphenylethylene or as phenylstilbene bromide, is a synthetic nonsteroidal estrogen of the triphenylethylene group that was marketed in the 1940s similarly to the closely related estrogen triphenylchloroethylene.
Droloxifene, also known as 3-hydroxytamoxifen, is a nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group that was developed originally in Germany and later in Japan for the treatment of breast cancer, osteoporosis in men and postmenopausal women, and cardiovascular disorders but was abandoned and never marketed. It reached phase II and phase III clinical trials for these indications before development was discontinued in 2000. The drug was found to be significantly less effective than tamoxifen in the treatment of breast cancer in two phase III clinical trials.
Panomifene is a nonsteroidal selective estrogen receptor modulator (SERM) of the triphenylethylene group related to tamoxifen that was under development as an antineoplastic agent by Egis Pharmaceuticals and IVAX Drug Research Institute in the 1990s for the treatment of breast cancer, but it was never marketed. It reached phase II clinical trials before development was terminated. The drug was described in 1981.
Dacuronium bromide is an aminosteroid neuromuscular blocking agent which was never marketed. It acts as a competitive antagonist of the nicotinic acetylcholine receptor (nAChR).
Pirenperone (INN, USAN, BAN; developmental code names R-47456, R-50656) is a serotonin receptor antagonist described as an antipsychotic and tranquilizer which was never marketed. It is a relatively selective antagonist of the serotonin 5-HT2 receptors and has been used in scientific research to study the serotonin system. In the 1980s, the drug was found to block the effects of the lysergic acid diethylamide (LSD) in animals, and along with ketanserin, led to the elucidation of the 5-HT2A receptor as the biological mediator of the effects of serotonergic psychedelics.
