Metabolite

A metabolite is the product of enzymatic transformation of a parent xenobiotic. In cannabis pharmacology, the principal Δ9-THC metabolites are: 11-hydroxy-Δ9-THC (11-OH-THC) — active, equipotent or stronger than THC at CB1, readily crosses the blood-brain barrier, generated especially after oral dosing and responsible for the prolonged, intense effects of edibles; and 11-nor-9-carboxy-Δ9-THC (THC-COOH) — inactive terminal oxidation product, highly lipophilic, accumulated in adipose tissue, and the primary analyte in urinary drug testing (Huestis 2005 Handb Exp Pharmacol). CBD is metabolized to 7-OH-CBD (possibly active) and 7-COOH-CBD. Minor metabolites include glucuronide conjugates, which facilitate renal/biliary elimination. Metabolite ratios (e.g., THC/THC-COOH in blood) are used in forensic toxicology to distinguish recent from remote use. Citations: Huestis MA. Handb Exp Pharmacol. 2005;168:657-690; Stout SM, Cimino NM. Drug Metab Rev. 2014;46:86-95; Grotenhermen F. Clin Pharmacokinet. 2003;42:327-360.