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Pharmacokinetics and subjective effects of a novel oral LSD formulation in healthy subjects

Article date: July 2019

By: Friederike Holze, Urs Duthaler, Patrick Vizeli, Felix Müller, Stefan Borgwardt, Matthias E. Liechti in Volume 85, Issue 7, pages 1474-1483


The aim of the present study was to characterize the pharmacokinetics and exposure–subjective response relationship of a novel oral solution of lysergic acid diethylamide (LSD) that was developed for clinical use in research and patients.


LSD (100 μg) was administered in 27 healthy subjects using a placebo‐controlled, double‐blind, cross‐over design. Plasma levels of LSD, nor‐LSD, and 2‐oxo‐3‐hydroxy‐LSD (O‐H‐LSD) and subjective drug effects were assessed up to 11.5 hours.


First‐order elimination kinetics were observed for LSD. Geometric mean maximum concentration (Cmax) values (range) of 1.7 (1.0–2.9) ng/mL were reached at a tmax (range) of 1.7 (1.0–3.4) hours after drug administration. The plasma half‐life (t1/2) was 3.6 (2.4–7.3) hours. The AUC was 13 (7.1–28) ng·h/mL. No differences in these pharmacokinetic parameters were found between male and female subjects. Plasma O‐H‐LSD but not nor‐LSD (< 0.01 ng/mL) concentrations could be quantified in all subjects. Geometric mean O‐H‐LSD Cmax values (range) of 0.11 (0.07–0.19) ng/mL were reached at a tmax (range) of 5 (3.2–8) hours. The t1/2 and AUC values of O‐H‐LSD were 5.2 (2.6–21) hours and 1.7 (0.85–4.3) ng·h/mL, respectively. The subjective effects of LSD lasted (mean ± SD) for 8.5 ± 2.0 hours (range: 5.3–12.8 h), and peak effects were reached 2.5 ± 0.6 hours (range 1.6–4.3 h) after drug administration. EC50 values were 1.0 ± 0.5 ng/mL and 1.9 ± 1.0 ng/mL for “good” and “bad” subjective drug effects, respectively.


The present study characterized the pharmacokinetics of LSD and its main metabolite O‐H‐LSD. The subjective effects of LSD were closely associated with changes in plasma concentrations over time.

DOI: 10.1111/bcp.13918

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