Time course of pharmacokinetic and hormonal effects of inhaled high-dose salvinorin A in humans

Introduction: Salvinorin A is a kappa opioid agonist and the principal psychoactive constituent of the Salvia divinorum plant, which has been used for hallucinogenic effects. Previous research on salvinorin A pharmacokinetics likely underestimated plasma levels typically resulting from the doses administered due to inefficient vaporization and not collecting samples during peak drug effects.Method: Six healthy adults inhaled a single high dose of vaporized salvinorin A (n = 4, 21 mcg/kg; n = 2, 18 mcg/kg). Participant- and monitor-rated effects were assessed every 2 min for 60 min post-inhalation. Blood samples were collected at 13 time points up to 90 min post-inhalation.Results: Drug levels peaked at 2 min and then rapidly decreased. Drug levels were significantly, positively correlated with participant and monitor drug effect ratings. Significant elevations in prolactin were observed beginning 5 min post-inhalation and peaking at 15 min post-inhalation. Cortisol showed inconsistent increases across participants. Hormonal responses were not well correlated with drug levels.Discussion: This is the first study to demonstrate a direct relationship between changes in plasma levels of salvinorin A and drug effects in humans. The results confirm the efficacy of an inhalation technique for salvinorin A.