Long-term stability of cannabinoids in oral fluid after controlled cannabis administration

Cannabinoid stability in oral fluid (OF) is important for assuring accurate results since OF has become a valid alternative matrix of choice for drug testing. We previously published OF cannabinoid stability studies using Quantisal™, Oral-Eze®, and StatSure™ devices stored at room temperature for 1 week, 4 °C for up to 4 weeks, and at -20 °C up to 24 weeks. Extending refrigerated stability up to 3 months would be helpful for clinical and forensic testing, for re-analysis of OF samples and for batching research analyses. Individual authentic OF pools were prepared after controlled smoking of a 6.9% ∆⁹ -tetrahydracannabinol cannabis cigarette; the Quantisal™ device was utilized for OF collection. Fifteen healthy volunteers participated in the Institutional Review Board-approved study. Stability for THC, 11-nor-9-carboxy-THC (THCCOOH), ∆⁹ -tetrahydrocannabivarin (THCV), cannabidiol (CBD), and cannabigerol (CBG) were determined after storage at 4 °C for 1, 2, and 3 months. Results within ±20% of baseline concentrations were considered stable. All analytes were stable for up to 2 months at 4 °C for all participants with positive baseline concentrations. Baseline concentrations were highly variable. In total, THC, THCCOOH, THCV, CBD, and CBG were stable for 3 months at 4 °C for pooled positive specimens from 14 of 15, 8 of 9, 7 of 8, 8 of 9, and 9 of 10 participants, respectively. In conclusion, Quantisal™-collected OF specimens should be stored at 4 °C for no more than two months to assure accurate THC, THCCOOH, THCV, CBD, and CBG quantitative results; only one participant's OF was unstable at three months. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.