Glutethimide and 4-OH glutethimide: pharmacokinetics and effect on performance in man.

The relationship between the plasma concentration of glutethimide (G) and the change from baseline of the standard error of the mean (deltaSDE) of a tracking test was determined in 7 volunteers. There was excellent positive correlation (r = 0.91) between log G and log deltaSDE and good correlation between log G and deltaSDE (r = 0.77). The metabolite, 4 hydroxyglutethimide, did not contribute significantly to the effect of G administered in therapeutic doses. No trend in performance versus level was found with 5 other tests (finger tapping, card sorting, digit substitution, subtraction, and subjective perception of drowsiness). Although the numbers were small, when the volunteers were divided into smokers (3) and nonsmokers (4) G decreased tracking ability to a greater extent in smokers than in nonsmokers.