Using a loose-leaf vaporizer to study tobacco-cannabis co-administration: A proof-of-concept study

We examined differences in Δ-9-tetrahydrocannabinol (THC) and nicotine intake, pharmacokinetics, subjective and physiologic effects from use of cannabis only, tobacco only, and a mixture of cannabis and tobacco using a PAX-3 vaporizer.

Eight (7M, 1F) healthy adults who use both cannabis and tobacco participated in a 3-arm, within-subject study. Participants were administered 3 standardized puffs of cannabis only, tobacco only, or a 50-50 mixture with a PAX-3. Blood was collected and questionnaires were administered before and after the last puff.

Average maximum plasma THC concentration (C_max) and area under the plasma THC concentration-time curve (AUC) were significantly higher after vaping the mixture compared to cannabis only [C_max: 25.7 ± 14.0ng/mL vs. 9.7 ± 6.5ng/mL, p < 0.04 (mean±SD); AUC: 590 ± 555ng/mL•min vs. 306 ± 258ng/mL•min, p < 0.02]. Similarly, plasma nicotine C_max and AUC_(0→360) were significantly higher after vaping the mixture compared to tobacco only [C_max: 1.6 ± 0.71ng/mL vs. 0.55 ± 0.32ng/mL, p < 0.02; AUC: 135 ± 35.7ng/mL•min vs. 63.1 ± 25.4ng/mL•min, p < 0.01]. Although elevated from use of the mixture, heart rate changes were not significantly different across study conditions. Subjective effects generally did not differ across study conditions, but this may have been due to the small sample size of the study.

Vaping cannabis and tobacco together leads to greater exposure to THC and nicotine than the substances by themselves. Despite differences in THC exposure, subjective effects and heart rate were not different between the mixture and cannabis only, indicating potential attenuation of THC-related effects by nicotine.