Assessing cannabis consumption frequency: Is the combined use of free and glucuronidated THCCOOH blood levels of diagnostic utility?
Publisher DOI
PubMed ID
27732768
Abstract
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.
Date Issued
2017-07
Publication Type
Article
Subject(s)
Subjects
THCCOOH
•
THCCOOH-glucuronide
•
cannabis
•
consumption frequency
•
whole blood
Language(s)
en
Author(s)
Journal
Drug testing and analysis
Publisher
Wiley
ISSN
1942-7603
Access(Rights)
open.access