This is a list of investigational antidepressants, or antidepressants that are currently under development for clinical use in the treatment of mood disorders but are not yet approved. Chemical/generic names are listed first, with developmental code names, synonyms, and brand names in parentheses. All drugs listed are specifically under development for major depressive disorder (MDD) and/or treatment-resistant depression (TRD) unless noted otherwise. Other forms of depression may include bipolar depression and postpartum depression.
Esketamine (Esketamine DPI, Falkieri, PG061) – non-competitive NMDA receptor antagonist – approved for TRD, specifically under development for bipolar depression and "depressive disorders" [1]
Esmethadone (dextromethadone; REL-1017) – NMDA receptor antagonist open channel blocker[5]
Aramisulpride/esamisulpride (85:15 ratio) (SEP-4199) – 5-HT7 receptor antagonist (aramisulpride) and D2 and D3 receptor antagonist (esamisulpride) – specifically under development for the treatment of bipolar depression[12][13]
Zuranolone (SAGE-217) – GABAA receptor positive allosteric modulator – specifically under development for the treatment of MDD and postpartum depression[22]
OnabotulinumtoxinA (botulinum toxin A, Botox) – acetylcholine release inhibitor – specifically under development for the treatment of MDD in women as a local injection to paralyze facial muscles[31]
Cycloserine/lurasidone (NRX-101; Cyclurad) – NMDA receptor glycine site partial agonist and AA combination – specifically under development for the treatment of bipolar depression[45]
Deudextromethorphan/quinidine (AVP-786, CTP-786) – σ1 receptor agonist, SRI, uncompetitive NMDA receptor antagonist, and other actions[46]
Not under development
The following notable drugs are of investigational interest as potential antidepressants but are not formally under clinical development for approval at this time:
Hydroxynorketamine ((2R,6R)-HNK) – metabolite of ketamine which may be involved in ketamine's antidepressant-like effects in mice[3][47]
Minocycline – microglia inhibitor and other actions; a 2018 systematic review and meta-analysis reported that the overall antidepressant effect size of minocycline compared to placebo was -0.78 (95% CI: -0.4 to -1.33, P=0.005), indicative of a large and statistically significant antidepressant effect[50][51]
↑"Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids". Journal of Ethnopharmacology137 (3): 1124–1129. October 2011. doi:10.1016/j.jep.2011.07.035. PMID21798331.
↑"High-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor". Journal of Ethnopharmacology177: 111–116. January 2016. doi:10.1016/j.jep.2015.11.034. PMID26615766.
↑"Efficacy and tolerability of minocycline for depression: A systematic review and meta-analysis of clinical trials". Journal of Affective Disorders227: 219–225. February 2018. doi:10.1016/j.jad.2017.10.042. PMID29102836.
↑"Small molecules activating TrkB receptor for treating a variety of CNS disorders". CNS & Neurological Disorders Drug Targets12 (7): 1066–77. November 2013. doi:10.2174/18715273113129990089. PMID23844685.
↑"Comparison of ketamine, 7,8-dihydroxyflavone, and ANA-12 antidepressant effects in the social defeat stress model of depression". Psychopharmacology232 (23): 4325–35. December 2015. doi:10.1007/s00213-015-4062-3. PMID26337614.
"Investigational drugs for treating major depressive disorder". Expert Opinion on Investigational Drugs26 (1): 9–24. January 2017. doi:10.1080/13543784.2017.1267727. PMID27960559.