Elimination of tritium-labelled cannabinols in the rat with special reference to the development of tests for the identification of cannabis users

Abstract A method is described for the preparation of tritium-labelled Δ9-tetrahydrocannabinol and other cannabinols. Intravenously injected Δ9-tetrahydrocannabinol-H 3 is eliminated very slowly by the rat; half of the administered dose still remained in the body after one week. About 80 per cent of the drug is excreted in metabolized form via faeces, the remainder being eliminated also as metabolites in the urine. During the first 24 hr 2–6 per cent of the injected activity appears in the urine, but less than 0.006 per cent of the dose, if any, is excreted unchanged. A considerable amount of the activity is readily extractable with ether and possibly an identification method for Cannabis-users may be based on the occurrence of this metabolite. Δ9-Tetrahydrocannabinol is apparently not excreted as a glucuronide.