A new study published by the National Institute on Drug Abuse specified that cannabis in combination with alcohol causes a higher increase in TCH concentrations in the blood. The main psychoactive component of Cannabis is TCH, which acts as the active ingredient for the drug.
The current movement to decriminalize Cannabis in a number of states has caused public health concerns including the fact that Cannabis is more easily available to teenagers. The current available statistics by the U.S. Department of Transportation has found an increased accident risk of 0.7 for cannabis use, 7.4 for alcohol use, and 8.4 for cannabis and alcohol use combined, in a study of 1,882 motor vehicle accidents.
The study participants consisted of 19 adult participants who drank placebo or low-dose alcohol (with a target peak breath-alcohol concentration of approximately 0.065%) 10 minutes prior to inhaling 500 mg of placebo, low-dose (2.9% THC), or high-dose (6.7% THC) vaporized cannabis.
The researchers found that with no alcohol, the median maximum blood concentrations for low and high THC doses were 32.7 and 42.2 µg/L THC, respectively, and 2.8 and 5.0 µg/L 11-OH-THC. With alcohol, the median maximum blood concentrations for low and high THC doses were 35.3 and 67.5 µg/L THC and 3.7 and 6.0 µg/L 11-OH-THC, which is significantly higher than without alcohol.
“The significantly higher blood THC and 11-OH-THC [median maximum concentration] values with alcohol possibly explain increased performance impairment observed from cannabis-alcohol combinations,” said lead study author Marilyn A. Huestis, PhD, of the National Institute on Drug Abuse, Baltimore, Maryland. “Our results will help facilitate forensic interpretation and inform the debate on drugged driving legislation.”
Marilyn A. Huestis, PhD et al. Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol. Clinical Chemistry, May 2015 DOI: 10.1373/clinchem.2015.238287