TY  - JOUR
PY  - 2016//
TI  - Assessing cannabis consumption frequency: is the combined use of free and glucuronidated THCCOOH blood levels of diagnostic utility?
JO  - Drug testing and analysis
A1  - Hädener, Marianne
A1  - Martin Fabritius, Marie
A1  - König, Stefan
A1  - Giroud, Christian
A1  - Weinmann, Wolfgang
SP  - 1043
EP  - 1051
VL  - 9
IS  - 7
N2  - Heavy cannabis consumption is considered incompatible with safe driving. In Swiss traffic policy, drivers suspected of regular cannabis use are therefore required to undergo medical assessment of their long-term fitness to drive. A whole blood concentration of the cannabis metabolite 11-nor-9-carboxy-Δ(9) -tetrahydrocannabinol (THCCOOH) of 40 µg/L is currently used by Swiss forensic experts as decision limit for regular cannabis consumption. The present study aimed to investigate the suitability of THCCOOH-glucuronide blood levels as an additional and/or better marker for the frequency of cannabis use. Whole blood samples collected from 23 heavy (≥10 joints/month) and 25 occasional smokers (≥1 joint/month, but ≤ 1 joint/week) enrolled in a placebo-controlled cannabis smoking study were analyzed for THCCOOH and THCCOOH-glucuronide. Based on ROC curve analysis concentration thresholds could be established for distinguishing between these two groups. Proposed thresholds for heavy use were THCCOOH-glucuronide > 52 µg/L (100% specificity; 41% sensitivity) and/or total THCCOOH > 58 µg/L (100% specificity; 43% sensitivity). Optimum thresholds for occasional use were THCCOOH-glucuronide < 5 µg/L (73% specificity; 97% sensitivity) and/or total THCCOOH < 5 µg/L (62% specificity; 98% sensitivity). Our results indicate that the THCCOOH-glucuronide whole blood concentration is a useful parameter that complements the free THCCOOH level to assess the frequency of cannabis consumption. The consideration of the blood concentrations of both free and glucuronidated THCCOOH improves the identification of heavy users whose fitness to drive has to be carefully assessed.<br><br>This article is protected by copyright. All rights reserved.<p />  <p>Language: en</p>
LA  - en
SN  - 1942-7603
UR  - http://dx.doi.org/10.1002/dta.2114
ID  - ref1
ER  -