Effect of subject expectancy on the THC intoxication and disposition from smoked hashish cigarettes

Abstract

Subject expectancy on cannabis effects was assessed in a balanced-placebo study in experienced consumers who smoked cigarettes containing hashish (200 mg hashish with 11.5% THC per 1 g tobacco cigarette) (n = 24) or placebo (n = 24). Although statistically significant differences were not found between subjects who received the drug with positive or negative expectancy, a tendency toward more marked subjective effects was shown in subjects who expected and received the drug. This trend was supported by the significant difference observed in the mean AUC0-25 of the heart rate between subjects who smoked hashish with positive or negative expectancies. In subjects who received hashish, the sum AUC0-205 of THC and COOH-THC of those who expected the drug was greater than in those who did not expect it (p less than 0.05). The ratio THC/COOH-THC AUC0-205 was lower in those with positive expectancy than in those with negative expectancy (p less than 0.02). An increased metabolism of THC was shown in subjects with positive expectancy. Positive expectancy induced powerful subjective effects in the absence of active THC. Expectancy appeared to influence smoking behavior, as seen in higher plasma levels of cannabinoids for the group who received the drug.