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

Abstract

Following oral ingestion of cannabis resin, delta 9-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 delta 9-THC. delta 9-THC-11-oic acid was not excreted in the urine in significant concentrations, the glucuronide conjugate being the major urinary metabolite detected. delta 9-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 delta 9-THC (20 mg). Estimates for the half life of delta 9-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.

Comparison of Cannabinoid Concentrations in Plasma, Oral Fluid and Urine in Occasional Cannabis Smokers After Smoking Cannabis Cigarette

“…The main urinary metabolite is eliminated such as THC-COOH-glucuronide [36]. THC-COOH free is present in urine in trace amounts [37,38,39]. Mean percentage of total THC dose excreted as THC-COOH metabolite was 1.9 +/-2.5%.…”

Review of Biologic Matrices (Urine, Blood, Hair) as Indicators of Recent or Ongoing Cannabis Use

“…After oral use, absorption is slow resulting in maximal THC plasma concentrations usually after 1 to 2 hours 7,10 ; in some cases maximal plasma concentrations were observed as late as 4 to 6 hours, 7,11 and several subjects showed more than one plasma peak. An extensive first-pass liver metabolism reduces the oral bioavailability of THC to 6% ± 3% (range, 4-12%).…”

“…The slow elimination is based on the slow rediffusion of THC from body fat and other tissues into the blood. After smoking a low-dose THC cigarette (16 mg), the limit of detection of 0.5 ng/mL of THC in plasma was reached after 7.2 (range, [3][4][5][6][7][8][9][10][11][12] hours, and after a high-dose cigarette (35 mg), the limit of detection was reached after 12.5 (range, hours. 4 THC-COOH was detectable for a considerably longer time of 3.5 (range, 2-7) days after the low dose and 6.3 (range, 3-7) days after smoking the high dose.…”

“…11,57,58 Generally these attempts have not been successful in predicting the time of exposure with reasonable accuracy. Huestis et al 59 reported on 2 mathematical models that are useful to predict the time of cannabis use.…”

Profils cinétiques du Δ9-tétrahydrocannabinol, du 11-hydroxy-Δ9-tétrahydrocannabinol et de l'acide 11-nor-Δ9-tétrahydrocannabinol- 9-carboxylique chez le sujet volontaire sain après administration orale de décoctions de cannabis ou de dronabinol

“…A notre connaissance, l'évaluation des effets d'une consommation orale de cannabis ou de THC pur sur la conduite automobile n'a pas encore été réalisée. Si plusieurs études d'administration orale de cannabis ont déjà été effectuées, les buts en étaient différents, il s'agissait notamment de comparer les pharmacoc i né-tiques des cannabinoïdes dans le plasma à celles obtenues lors d'une injection intraveineuse ou d'une inhalation de cannabis ou d'évaluer les effets cognitifs, subjectifs, physiologiques ou thérapeutiques du cannabis et du THC oral (21,28,(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45) …”