Study Summary

Sixteen healthy subjects were included in this double-blind, placebo-controlled, cross-over study examining the single-dose kinetics and pharmacokinetic-pharmacodynamic relationships of oral lysergic acid diethylamide (LSD). Participants were given 200 μg LSD or placebo over 2 experimental test sessions with a washout period of at least 7 days between sessions. LSD and 2-oxo-3-hydroxy-lysergic acid diethylamide (O-H-LSD) concentrations in plasma and urine were determined using a validated liquid-chromatography-tandem mass-spectrometry, and drug effect was measured using the visual analogue scale. The acute subjective and sympathomimetic responses to lysergic acid diethylamide lasted up to 12 hours and were closely associated with the concentrations in plasma over time. Maximal concentrations of lysergic acid diethylamide were reached 1.5 (median, range 0.5-4) hours after administration. One percent of the orally administered LSD was eliminated in urine as LSD, and 13% was eliminated as O-H-LSD within 24 hours.