Delta-9 THC

Δ⁹-THC (delta-9-tetrahydrocannabinol) is the principal intoxicating constituent of Cannabis sativa and the reference compound against which other cannabinoids are compared. Structurally it differs from its Δ⁸ isomer by the position of a single double bond in the cyclohexene ring (between C9 and C10, using dibenzopyran numbering). Pharmacokinetically, inhaled Δ⁹-THC reaches peak plasma concentrations within minutes, while oral bioavailability is low (~6–20%) and highly variable due to first-pass metabolism via CYP2C9 and CYP3A4 to the active 11-hydroxy-THC and then to 11-nor-9-carboxy-THC (Huestis, 2007, Chemistry & Biodiversity 4:1770). FDA-approved as dronabinol (Marinol, 1985) and present in nabiximols (Sativex). The 2017 NASEM report concluded there is "conclusive or substantial" evidence for efficacy in chemotherapy-induced nausea, chronic pain, and multiple-sclerosis spasticity. → See also: THC, THCA, CB1 receptor.