Urinary elimination half-life of delta-1-tetrahydrocannabinol-7-oic acid in heavy marijuana users after smoking

The urinary excretion of delta 1-tetrahydrocannabinol-7-oic acid (delta 1-THC-7-oic acid), the major urinary metabolite of delta 1-THC, and the total amount of THC metabolites was studied in heavy marijuana users after smoking using high-performance liquid chromatography and the EMT-d.a.u. cannabinoid assay. An average elimination half-life (+/- SD) of 3.0 +/- 2.3 days was obtained for delta 1-THC-7-oic acid. The average ratio (+/- SD) of "EMIT readings"/delta 1-THC-7-oic acid concentrations was 1.23 +/- 1.03.