Anti-emetic

An anti-emetic is a pharmacological agent that suppresses nausea and vomiting. Cannabinoid anti-emetics, including Δ9-tetrahydrocannabinol (THC) and the FDA-approved synthetic analogues dronabinol (Marinol) and nabilone (Cesamet), act primarily as partial agonists at CB1 receptors expressed in the dorsal vagal complex and area postrema of the brainstem, attenuating emetic signaling mediated by serotonergic and dopaminergic inputs. The National Academies of Sciences, Engineering, and Medicine (NASEM 2017, The Health Effects of Cannabis and Cannabinoids) concluded there is conclusive evidence that oral cannabinoids are effective antiemetics for chemotherapy-induced nausea and vomiting (CINV), the strongest therapeutic rating in the report. A Cochrane review by Smith et al. (2015) of 23 randomized trials supported cannabinoids as useful for refractory CINV, though adverse events (dizziness, dysphoria, sedation) limit first-line use relative to 5-HT3 antagonists. Paradoxically, chronic heavy cannabis use is associated with the pro-emetic Cannabinoid Hyperemesis Syndrome. → See also: THC, CB1 Receptor, Dronabinol, CHS.