Influence of Ethanol on the Pharmacokinetic Properties of Delta D9-Tetrahydrocannabinol in Oral Fluid

• Published in: Journal of analytical toxicology Vol. 37; no. 3; pp. 152 - 158
• Main Authors: Toennes, Stefan W, Schneider, Kirsten, Wunder, Cora, Kauert, Gerold F, Moeller, Manfred R, Theunissen, Eef L, Ramaekers, Johannes G
• Format: Journal Article
• Language: English
• Published: 01-04-2013
• ISSN: 0146-4760

Oral fluid (OF) tests aid in identifying drivers under the influence of drugs. In this study, 17 heavy cannabis users consumed alcohol to achieve steady blood alcohol concentrations of 0 to 0.7 g/L and smoked cannabis 3 h afterward. OF samples were obtained before and up to 4 h after smoking and on-site tests were performed (Drager DrugTest 5000 and Securetec DrugWipe 5+). Maximum concentrations of tetrahydrocannabinol (THC) immediately after smoking (up to 44,412 ng/g) were below 4,300 (median 377) ng/g 1 h after smoking and less than 312 (median 88) ng/g 3 h later with 5 of 49 samples negative, suggesting that recent cannabis use might occasionally not be detectable. An influence of alcohol was not observed. Drinking 300 mL variably influenced THC concentrations (median only -29.6%), which suggests that drinking does not markedly affect on-site test performance. Many (92%) Drager tests performed 4 h after smoking were still positive, indicating sufficient sensitivity for recent cannabis use. Differences in the results of a roadside study with DrugTest 5000 (sensitivity 84.8%, specificity 96.0%, accuracy 84.3%) could be explained by a higher number of true negatives, differences between OF and serum and differences between occasional and chronic users.