Dextromethorphan (DXM), sold under the trade name Robitussin among others, is a cough suppressant used in many cough and cold medicines.[6] It affects serotonin, norepinephrine, NMDA, and sigma-1 receptors in the brain, all of which have been implicated in the pathophysiology of depression. In 2022, the FDA approved the combination dextromethorphan/bupropion to serve as a rapid acting antidepressant in patients with major depressive disorder.[7]
It is in the morphinan class of medications with sedative, dissociative, and stimulant properties (at lower doses). Dextromethorphan does not have a significant affinity for the mu-opioid receptor activity typical of morphinan compounds and exerts its therapeutic effects through several other receptors.[8] In its pure form, dextromethorphan occurs as a white powder.[9]
^Kukanich B, Papich MG (October 2004). "Plasma profile and pharmacokinetics of dextromethorphan after intravenous and oral administration in healthy dogs". Journal of Veterinary Pharmacology and Therapeutics. 27 (5): 337–341. doi:10.1111/j.1365-2885.2004.00608.x. PMID15500572.
^Dicpinigaitis P (2022-09-12). "The Current and Emerging Treatment Landscape for Chronic Cough". The American Journal of Managed Care. Uncovering the Economic Burden of Chronic Cough and the Promising Role of Emerging Targeted Therapies. 28 (9): S159–S165. doi:10.37765/ajmc.2022.89244. PMID36198074. S2CID252736111. By sales, dextromethorphan is the most widely used OTC antitussive drug in the United States, and approximately 85% to 90% of OTC cough medicines contain dextromethorphan
^Majeed A, Xiong J, Teopiz KM, Ng J, Ho R, Rosenblat JD, et al. (March 2021). "Efficacy of dextromethorphan for the treatment of depression: a systematic review of preclinical and clinical trials". Expert Opinion on Emerging Drugs. 26 (1): 63–74. doi:10.1080/14728214.2021.1898588. PMID33682569. S2CID232141396.