Detection of Δ9‐tetrahydrocannabinol (THC) in oral fluid using two point‐of‐collection testing devices following oral administration of a THC and cannabidiol containing oil

Abstract

AbstractPoint‐of‐collection testing (POCT) devices are widely used in roadside and workplace drug testing to identify recent cannabis use by measuring the presence of Δ9‐tetrahydrocannabinol (THC) in oral fluid (OF). However, the performance of POCT devices with oral medicinal cannabis products remains poorly described. In a randomised, double‐blinded, crossover trial, adults with insomnia disorder (n = 20) received a single (2 mL) oral dose of oil containing 10 mg THC + 200 mg cannabidiol, or placebo, prior to sleep. Participants were tested with the Securetec DrugWipe® 5S (10 ng/mL THC cut‐off) and Dräger DrugTest® 5000 (25 ng/mL THC cut‐off) POCT devices at baseline (pre‐treatment) and then at 0.5, 10, and 18 h post‐treatment. An OF sample, taken at each time point, was also analysed using liquid chromatography–tandem mass spectrometry. Large individual variability in OF THC concentrations was observed 0.5 h post‐treatment (range: 0–425 ng/mL; mean (SD) 48.7 (107.5) ng/mL). Both the Securetec DrugWipe® 5S and DrugTest® 5000 demonstrated poor sensitivity to THC at 0.5 h post‐treatment (25% and 50%, respectively). At 10 and 18 h post‐treatment, all participant OF THC concentrations were below screening cut‐offs, and all test results were negative. These findings highlight the relatively poor sensitivity of both devices in detecting recent use of an oral medicinal cannabis product. They also suggest a low probability of obtaining a positive THC result the morning after (‘one‐off’) use. Further research is required to establish the probability of obtaining a positive THC result with regular medicinal cannabis use.