RESIDUAL EFFECTS OF EVENING AND MIDDLE-OF-THE-NIGHT ADMINISTRATION OFZALEPLON-10 AND ZALEPLON-20 MG ON MEMORY AND ACTUAL DRIVING PERFORMANCE

Zaleplon, a new pyrazolopyrimidine hypnotic, possesses an unusually sh ort elimination half-life (ca 1 h). This study was conducted to determ ine whether middle-of-the-night administration of zaleplon affects mem ory or driving performance the following morning. Twenty-eight healthy volunteers participated in a double-blind, 7-way, crossover study. Th ey ingested capsules twice on each treatment night; once before initia ting sleep and again after being briefly awakened 5 h later. Treatment s were: placebo at both times, zaleplon 10 or 20 mg, or zopiclone 7.5 mg followed by placebo, or the same in reverse order. Subjects arose 3 h after the second dose. One hour later, sleep quality and mood were assessed by questionnaires and balance and memory in a test battery. A standardized actual driving test was undertaken between 5 and 6 h aft er the second dose. All drugs similarly improved sleep quality, but on ly zopiclone hindered awakening. Evening zaleplon doses were without s ignificant effects. Late-night zaleplon had minor effects in one memor y test. Evening zopiclone shared these effects and also significantly impaired driving performance. Late-night zopiclone's effects were sign ificant in every test. Its effects on driving were severe. The results suggest that zaleplon 10 mg certainly, and 20 mg probably, can be tak en at bedtime or later in the night,up to 5 h before driving with litt le risk of serious impairment. (C) 1998 John Wiley & Sons, Ltd.