Alcohol Changed Selected THC Pharmacokinetic Measures Without Uniform Metabolite Effects
Alcohol did not shift every cannabinoid measurement in the same direction in a controlled study of heavy cannabis users. Selected THC pharmacokinetic changes occurred while metabolite comparisons remained nonsignificant.
The observed alcohol levels differed from targets
Nineteen heavy cannabis users received three alcohol conditions, then smoked a THC cigarette during the dosing period. The reported mean steady alcohol concentrations were lower than the planned targets. An account of the experiment should use achieved exposure rather than present the targets as observed values.
Some THC results changed
The higher alcohol condition was associated with a modestly longer apparent THC elimination half-life and a lower concentration at one reported post-smoking time. The authors proposed distribution between compartments as one possible explanation.
Metabolite findings were not equivalent positives
The abstract reports no significant ethanol effect on the measured pharmacokinetics of 11-hydroxy-THC or the carboxy metabolite. A visually lower or numerically different concentration is not automatically a statistically established effect.
The study used serial blood sampling; its measurements should retain the exact analytical matrix when quantitative values are applied elsewhere. An apparent half-life is not the duration of intoxication and does not determine a person's driving clearance. Nor do these exposure findings establish behavioral cross-tolerance to alcohol. The useful result is an analyte- and time-specific interaction under a defined research regimen.
Related: interpreting cannabis tolerance claims.
Research cited
Toennes SW; Schneider K; Kauert GF; Wunder C; Moeller MR; Theunissen EL; Ramaekers JG. Influence of ethanol on cannabinoid pharmacokinetic parameters in chronic users. Analytical and bioanalytical chemistry (2011). doi:10.1007/s00216-010-4449-2. Findings discussed from the study abstract.
