title: Urinary excretion half-life of delta 1-tetrahydrocannabinol-7-oic acid in heavy marijuana users after smoking.
abstract: The urinary excretion of the total amount of delta 1-tetrahydrocannabinol (delta 1-THC) metabolites, with special emphasis on delta 1-tetrahydrocannabinol-7-oic acid (delta 1-THC-7-oic acid), was studied in thirteen heavy Cannabis users after smoking administration of delta 1-THC, followed by a four week discontinuation period. The total amount of delta 1-THC metabolites and the levels of delta 1-THC-7-oic acid could be followed up to 25 days after abstinence using EMIT d.a.u. cannabinoid assay and high-performance liquid chromatography (HPLC). The urinary excretion half-life, calculated from the concentrations of delta 1-THC-7-oic acid versus time, ranged from 0.8-9.8 days with a mean (+/- SD) of 3.0 +/- 2.3 days. Most of the delta 1-THC-7-oic acid was excreted as conjugate and only trace amounts of unconjugated delta 1-THC-7-oic acid were detected. The total concentrations of delta 1-THC-7-oic acid in urine were compared to the concentrations of "cross-reacting cannabinoids", within the linear range of 20-75 ng/mL, obtained in the semiquantitative EMIT d.a.u. cannabinoid assay. The average ratio of "EMIT concentrations"/delta 1-THC-7-oic acid concentrations obtained by HPLC analysis was 1.23 +/- 84% (C.V.) for 78 urine samples. A total of 83% of the samples with positive EMIT levels (cutoff 20 ng/mL) was confirmed by HPLC analysis (cutoff 7 ng/mL).
authors.affiliation: Department of Pharmacognosy, Uppsala, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Johansson
authors.forename: M M
authors.initials: MM
authors.lastname: Halldin
mesh_terms: D002186:Cannabinoids / Q000652:urine; D013759:Dronabinol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics / Q000652:urine; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000378:metabolism / Q000652:urine*
chemical_list: D002186:Cannabinoids; C009411:delta(6)-tetrahydrocannabinol-7-oic acid; D013759:Dronabinol