Forensic aspects of the metabolism and excretion of cannabinoids following oral ingestion of cannabis resin

Abstract

Abstract Following oral ingestion of cannabis resin, δ9-THC−11−oic acid and its O-ester glucuronide were detected using RIA and combined hplc/RIA and shown to be major plasma metabolites of δ9-THC. δ9-THC−11−oic acid was not excreted in the urine in significant concentrations, the glucuronide conjugate being the major urinary metabolite detected. δ9-THC metabolites were detected in blood for up to 5 days and in urine for up to 12 days following a single oral dose of δ9-THC (20 mg). Estimates for the half life of δ9-THC−11−oic acid and its glucuronide in plasma, and total metabolites in urine have been obtained. Interpretation of blood or urine total cannabinoid levels is most difficult, however, drug/metabolite ratios and metabolite/metabolite ratios may have potential for indicating recent cannabis use.