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Pharmacokinetics and concentration-effect relationship of oral LSD in humans

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Background: The pharmacokinetics of oral lysergic acid diethylamide (LSD) are unknown, despite its common recreational use and renewed interest in its use in psychiatric research and practice.

Methods: We characterized the pharmacokinetic profile, pharmacokinetic-pharmacodynamic relationship, and urine recovery of LSD and its main metabolite after administration of a single oral dose of LSD (200 μg) in eight male and eight female healthy subjects.

Results: Plasma LSD concentrations were quantifiable (> 0.1 ng/ml) in all of the subjects up to 12 h after administration. Maximal concentrations of LSD (mean ± SD: 4.5 ± 1.4 ng/ml) were reached (median, range) 1.57 (0.5-4) h after administration. Concentrations then decreased following first-order kinetics with a half-life of 3.6 ± 0.9 h up to 12 h and slower elimination thereafter with a terminal half-life of 8.9 ± 5.9 h. One percent of the orally administered LSD was eliminated in urine as LSD, and 14% was eliminated as 2-oxo-3-hydroxy-LSD within 24 h. No sex differences were observed in the pharmacokinetic profiles of LSD. The acute subjective and sympathomimetic responses to LSD lasted up to 12 h and were closely associated with the concentrations in plasma over time and exhibited no acute tolerance.

Conclusions: These first data on the pharmacokinetics and concentration-effect relationship of oral LSD are relevant for further clinical studies and serve as a reference for the assessment of intoxication with LSD.

Dolder, P. C., Schmid, Y., Haschke, M., Rentsch, K. M., & Liechti, M. E. (2015). Pharmacokinetics and concentration-effect relationship of oral LSD in humans. International Journal of Neuropsychopharmacology, pyv072.

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