Oral Δ9-tetrahydrocannabinol (THC) is effective for attenuating cannabis withdrawal and may benefit treatment of cannabis use disorders. Oral fluid (OF) cannabinoid testing, increasing in forensic and workplace settings, could be valuable for monitoring during cannabis treatment.
Eleven cannabis smokers resided on a closed research unit for 51 days, and received daily 0, 30, 60, and 120 mg oral THC in divided doses for 5 days. There was a 5-puff smoked cannabis challenge on the 5thday. Each medication session was separated by 9 days of ad libitum cannabis smoking. OF was collected the evening prior to and throughout oral THC sessions and analyzed by 2-dimensional GC-MS for THC, cannabidiol (CBD), cannabinol (CBN), 11-hydroxy-THC (11-OH-THC), and 11-nor-9-carboxy-THC (THCCOOH).
During all oral THC administrations, THC OF concentrations decreased to ≤78.2, 33.2, and 1.4 μg/L by 24, 48, and 72h, respectively. CBN also decreased over time with concentrations 10-fold lower than THC, with none detected beyond 69h. CBD and 11-OH-THC were rarely detected, only within 19 and 1.6h post smoking, respectively. THCCOOH OF concentrations were dose-dependent and increased over time during 120 mg THC dosing. After cannabis smoking, THC, CBN, and THCCOOH concentrations showed a significant dose-effect and decreased significantly over time.
Oral THC dosing significantly affected OF THCCOOH but minimally contributed to THC OF concentrations; prior ad libitum smoking was the primary source of THC, CBD and CBN. Higher cannabinoid concentrations following active oral THC administrations versus placebo suggest a compensatory effect of THC tolerance on smoking topography.
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