Plasma concentrations of LSD have not been determined in any of the published LSD fMRI studies to date therefore, it is unclear how LSD exposure in the body is linked to subjective effects in these studies. This approach likely detects significant correlations for subjective effects that show large between-subject variance but not for subjective effects of the substance that are consistently present in all subjects. Researchers have correlated subjective drug effects with brain functional magnetic resonance imaging (fMRI) data.

A second goal was to link the plasma concentration changes over time within subjects to the acute subjective and autonomic effects of LSD to derive half-maximal effective concentration (EC 50) values using standard pharmacokinetic-pharmacodynamic modeling.

Therefore, the primary goal of the present study was to describe the pharmacokinetics of a controlled administration of oral LSD by assessing the plasma concentration-time profile of two doses of LSD (100 and 200 µg). Unknown are the time point at which peak concentrations are reached and the actual or predicted concentrations of LSD at the time point at which pharmacodynamic outcomes were collected. However, plasma exposure and thus the actual presence of LSD in the body have not been documented in any of these studies to date. Recent studies have reported the effects of LSD on various neuronal correlates of brain activation. The concentrations of LSD were maximal after 1.5 h (median) and gradually declined to very low levels by 12 h, with an elimination half-life of 3.6 h. We recently reported the first pharmacokinetic data for orally administered LSD (200 µg) in 16 male and female subjects. Another non-systematic study sampled blood after administration of LSD 160 µg in 13 subjects up to 2.5–5 h but because of sparse and short sampling could not derive pharmacokinetic parameters. A small study in five male subjects reported a mean plasma elimination half-life of LSD of 175 min after intravenous administration (2 µg/kg). However, basic pharmacokinetic information on LSD is largely missing. Additionally, considerable interest has been seen in its therapeutic potential, and experimental clinical research with LSD has recently been reinitiated. Lysergic acid diethylamide continues to be used for recreational and personal purposes. Lysergic acid diethylamide has seen worldwide interest with regard to pharmacology, psychiatry, and society at large. Lysergic acid diethylamide (LSD) is the prototypical hallucinogen.

Half life 2 completo