Controlled cannabis vaporizer administration: Blood and plasma cannabinoids with and without alcohol (2015)

ENGLISH:
BACKGROUND: Increased medical and legal cannabis intake is accompanied by greater use of cannabis vaporization and more cases of driving under the influence of cannabis. Although simultaneous Delta9-tetrahydrocannabinol (THC) and alcohol use is frequent, potential pharmacokinetic interactions are poorly understood. Here we studied blood and plasma vaporized cannabinoid disposition, with and without simultaneous oral low-dose alcohol.
METHODS: Thirty-two adult cannabis smokers (>=1 time/3 months, <=3 days/week) drank placebo or low-dose alcohol (target approximately 0.065% peak breath-alcohol concentration) 10 min before inhaling 500 mg placebo, low-dose (2.9%) THC, or high-dose (6.7%) THC vaporized cannabis (6 within-individual alcohol-cannabis combinations). Blood and plasma were obtained before and up to 8.3 h after ingestion.
RESULTS: Nineteen participants completed all sessions. Median (range) maximum blood concentrations (Cmax) for low and high THC doses (no alcohol) were 32.7 (11.4-66.2) and 42.2 (15.2-137) µg/L THC, respectively, and 2.8 (0-9.1) and 5.0 (0-14.2) µg/L 11-OH-THC. With alcohol, low and high dose Cmax values were 35.3 (13.0-71.4) and 67.5 (18.1-210) µg/L THC and 3.7 (1.4-6.0) and 6.0 (0-23.3) µg/L 11-OH-THC, significantly higher than without alcohol. With a THC detection cutoff of >=1 µg/L, >=16.7% of participants remained positive 8.3 h postdose, whereas <=21.1% were positive by 2.3 h with a cutoff of >=5 µg/L.
CONCLUSIONS: Vaporization is an effective THC delivery route. The significantly higher blood THC and 11-OH-THC Cmax values with alcohol possibly explain increased performance impairment observed from cannabis-alcohol combinations. Chosen driving-related THC cutoffs should be considered carefully to best reflect performance impairment windows. Our results will help facilitate forensic interpretation and inform the debate on drugged driving legislation.
FRANÇAIS :
L'association cannabis-alcool tend à potentialiser le pouvoir des cannabinoïdes avec des taux de THC plus élevés que lors d'une consommation de cannabis seul, y compris lorsque le cannabis est inhalé par l'intermédiaire d'un vaporisateur. Ces valeurs plus élevées pourraient par ailleurs expliquer l'altération des performances des individus observée lors de ces polyconsommations et devraient à ce titre constituer un terrain d'investigation privilégié dans le cadre de la réglementation des conduites sous influence de substances. Ce sont les conclusions d'une étude contrôlée ayant mesuré la concentration de THC dans le sang et le plasma de 19 individus ayant inhalé du cannabis à faible dose/forte dose et consommé dans le même temps de l'alcool à faible dose VS placébo. [Actualités des addictions, 19/06/2015]