Amnesic Effects of Lormetazepam

Abstract

Sixteen healthy men, age 18–35, each received lormetazepam (1.5 mg), flurazepam (30 mg), temazepam (30 mg) and placebo (double-blind in a Latin Square design) 30 min before bedtime for 2 consecutive nights followed by a 12 day washout between conditions. Three hours after drug (2.5 h after bedtime) subjects were awakened and administered a 16-item memory task. Fifteen minutes after the awakening subjects returned to bed, were instructed to go to sleep, and remained in bed for an additional 5.5 h. Immediately after the memory tasks, before returning to bed, subjects recalled almost all of the 16 items when placebo was administered before bedtime. Immediate recall was significantly poorer than placebo after temazepam and flurazepam, but not after lormetazepam. Morning recall was reduced significantly from the immediate nighttime level in each condition; this loss was smallest with placebo. All active drug conditions produced significantly greater amnesia than placebo. This amnesia was smallest after lormetazepam and greatest after temazepam, which differed significantly from each other. All active drugs significantly reduced latency measures of the return to sleep after the 15 min awakening; it was shortest with temazepam and longest with flurazepam. This study showed a relation between the hypnotic and amnesic effects of these drugs which is consistent with their pharmacokinetic properties.