Correlation of performance test scores with “tissue concentration” of lysergic acid diethylamide in human subiects

A previously published two-compartment open model explains plasma concentrations of LSD-25 after intravenous injection of 2 mcg per kilogram of body weight. Performance scores on arithmetic tests were highly linearly correlated with the drug's concentration in the outer (tissue) compartment. The estimated volume of the inner (plasma) compartment was 16.3 percent of body weight, close to the value for extracellular water; the tissue compartment volume was 11.5 percent of body weight. The model-estimated half-life for loss of LSD-25 from the plasma compartment was 103 minutes, compared with a directly calculated half-life of 180 minutes.

Study at a glance

Abstract

Previously published plasma concentrations of LSD‐25, observed following intravenous iniection of 2 mcg. per kilogram of LSD‐25, have been found to be explained by the two‐compartment open model. Performance scores on arithmetic tests were shown to be highly linearly correlated with the concentration in the “tissue” (outer) compartment. The estimated volume of the plasma (inner) compartment was 16.3 per cent of body weight, which is approximately the value reported for extracellular water; the estimated volume of the tissue compartment was 11.5 per cent of body weight. The estimated half‐life for loss of LSD‐25 from the plasma compartment, based on the model, was 103 minutes compared with a half‐life of 180 minutes calculated directly from plasma concentrations.