Antidepressants

Ifoxetine (CGP-15,210-G) is a selective serotonin reuptake inhibitor (SSRI) which was investigated as an antidepressant in the 1980s but was never marketed. Ifoxetine selectively blocks the reuptake of serotonin in the brain supposedly without affecting it in the periphery. Supporting this claim, ifoxetine was found to be efficacious in clinical trials and was very well tolerated, producing almost no physical side effects or other complaints of significant concern.

Amixetrine (INN; brand name Somagest; developmental code CERM-898) is a drug that was formerly marketed in France but is now no longer sold. According to various sources it has been said to be an anti-inflammatory, antidepressant, antispasmodic, anticholinergic, antihistamine, and antiserotonergic, but its definitive indications and pharmacology are unclear. The drug was first synthesized in 1969 and was introduced in France in 1972.

Sercloremine (CGP-4718A), usually as the hydrochloride salt, is a drug which was developed in the 1980s and was formerly under investigation as an antidepressant, but was never marketed. It acts as a selective, reversible inhibitor of monoamine oxidase A (RIMA) and serotonin reuptake inhibitor.

Fenmetramide is a drug which was patented as an antidepressant by McNeil Laboratories in the 1960s. The drug was never marketed. It is the 5-ketone derivative of phenmetrazine and would similarly be expected to produce psychostimulant effects, though pharmacological data is lacking.

Carbenzide (INN), is a hydrazine derivative monoamine oxidase inhibitor (MAOI) antidepressant which was never marketed.

Hydroxynorketamine (HNK), or 6-hydroxynorketamine, is a minor metabolite of the anesthetic, dissociative, and antidepressant drug ketamine. It is formed by hydroxylation of the intermediate norketamine, another metabolite of ketamine. As of late 2019, '(2R,6R)-HNK' is in clinical trials for the treatment of depression.

Fenpentadiol (INN; brand names Tredum, Trefenum; developmental code Rd-292; also known as phenpentanediol) is a drug described as a tranquilizer and antidepressant that was formerly marketed in Europe. It also has stimulant, sedative, and anxiolytic effects, with the latter two occurring only at higher doses.

Ketipramine (G-35,259), also known as ketimipramine or ketoimipramine, is a tricyclic antidepressant (TCA) that was tested in clinical trials for the treatment of depression in the 1960s but was never marketed. It differs from imipramine in terms of chemical structure only by a single ketone group, and is approximately equivalent in effectiveness as an antidepressant in comparison.

Rapastinel () (former developmental code name GLYX-13) is a novel antidepressant that was under development by Allergan (previously Naurex) as an adjunctive therapy for the treatment of treatment-resistant depression. It is a centrally active, intravenously administered (non-orally active) amidated tetrapeptide that acts as a novel and selective modulator of the NMDA receptor. The drug is a rapid-acting and long-lasting antidepressant as well as robust cognitive enhancer by virtue of its ability to enhance NMDA receptor-mediated signal transduction and synaptic plasticity.

Metostilenol is a drug which was patented as an antidepressant in the early 1980s, but was never marketed.

Cimemoxin (INN), or cyclohexylmethylhydrazine, is a hydrazine monoamine oxidase inhibitor (MAOI) antidepressant which was never marketed.

Norketamine, or '''N-desmethylketamine''', is the major active metabolite of ketamine, which is formed mainly by CYP3A4. Similarly to ketamine, norketamine acts as a noncompetitive NMDA receptor antagonist, but is about 3–5 times less potent as an anesthetic in comparison.

Paraxazone is an antidepressant. It acts as a reversible inhibitor of the enzyme monoamine oxidase (MAO). It was never marketed.