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Tuesday, August 26 Metabolism and Disposition of Drugs

Giroud C., Augsburger M., Rivier L., Mangin P.
Laboratoire de Toxicologie Analytique, IUML, Rue du Bugnon 21, CH-1005, Lausanne, Switzerland

During the last years, many hemp shops have been opened in Switzerland, selling seeds, plantlets, cosmetics, foodstuffs, etc. all made from cannabis. Recently, the Swiss Federal Office for Public Health issued provisional instructions in order to regulate the production of hemp foodstuffs. For instance, hemp teas made by pouring 200 mL of boiling water on 3 g of hemp must not contain more than 0.2 mg/kg of THC. In order to determine the circumstances other than drug abuse that could result in a positive test for cannabinoids, urinary excretion studies were performed with one volunteer following consumption of one cup of hemp tea. Since the ingestion of herbal milk teas by some "THC" abusers is a common practice, urinary excretion profiles were determined following intake of one cup of hemp milk tea.

Blood samples were collected and concentrations of THC, 11-OH-THC and carboxy-THC measured by GC/MS. The cannabinoid content of the plant material and the amount of free THC extracted during the two "tea-making" processes were also determined. Our results show that higher levels of free THC were extracted when milk was used instead of water for the preparation of the filtered hemp infusion (approx. 50 times). The total THC (THC + decarboxylated THC acid) concentration in the plant material was in the range of 0.5% g/g dry weight. In both cases, the infusion was prepared by boiling 3.6 g of plant material (a commercially available preparation made according to the manufacturer from dried flowers of Swiss natural hemp) in 200 ml of water or milk during half an hour. Urine remained positive (cut-off value: 15 ng carboxy-THC/ml) for about 41 hours and 140 hours following the intake of one cup of hemp tea infused with water or milk, respectively. Peak carboxy-THC concentrations were about 10 times higher with hem milk tea, reaching about 225 ng/ml urine. Moreover, significant levels of THC and metabolites were measured in blood samples collected 1, 3 and 5 hours after intake of the milk hemp tea. Maximum concentrations were in the range of 1.5, 7.3 and 23.6 ng/ml for THC, 11-OH-THC and carboxy-THC respectively. Only a mild euphoriant effect was reported after drinking a cup of the water infusion while strong intoxicant effects were noted following the ingestion of the hemp milk tea.

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