A double-blind study to establish the residual effects of zopiclone on performance in healthy volunteers.

Abstract

A double-blind study was designed to establish the residual effects of zopiclone on performance in healthy volunteers. 10 healthy male volunteers aged 22-45 years (mean age 27.4 years) were included in this study. 6 of the volunteers were cigar/cigarette smokers and were asked to smoke as little as possible on the study days. The subjects were randomly allocated to a balanced design in which each subject received single oral doses of placebo, 2.5-, 5-, 7.5- and 10-mg tablets of zopiclone under double-blind conditions. A battery of tests were performed 10 and 13 h after overnight ingestion of the drug. The tests comprised: EEG, auditory reaction time, tapping rate, digit symbol substitution test, symbol copying test, mood rating scales, side effects rating scales, and subjective assessments of sleep and performance. Zopiclone is shown to have useful hypnotic properties but residual effects are detectable using EEG and psychological tests both 10 and 13 h after ingestion. The 10-mg dose significantly impairs performance the next day; the 5-mg dose is almost devoid of residual psychomotor effects but is only marginally effective in hastening onset of sleep and does not improve sleep quality. The 7.5-mg dose has definite effects on sleep and limited residual effects the next day. No significant side effects were reported. In this study, using single doses in healthy subjects, the best balance between wanted hypnotic effects and unwanted residual effects the next day was provided by the 7.5-mg dose of zopiclone. It is recommended that further studies with repeated doses in healthy volunteer subjects and in insomniac patients use the 7.5-mg dose as the reference point.