Zaleplon improves sleep without producing rebound effects in outpatients with insomnia. Zaleplon Clinical Study Group

The efficacy and safety of three doses of zaleplon, a novel non-benzodiazepine hypnotic, were compared with those of placebo in outpatients with insomnia in this 4-week study, using zolpidem 10 mg as active comparator. Postsleep questionnaires were used to determine treatment effects on the patient's perception of sleep, as well as any development of pharmacological tolerance during therapy or rebound insomnia or withdrawal symptoms upon discontinuation of therapy. During week 1, sleep latency was significantly shorter with zaleplon 5, 10, and 20 mg compared to placebo. The significant decrease in sleep latency persisted through week 4 with zaleplon 20 mg, and was again evident with zaleplon 10 mg at week 3. Zaleplon 20 mg also had significant effects on sleep duration, number of awakenings, and sleep quality compared to placebo. No pharmacological tolerance developed during treatment with zaleplon and there were no indications of rebound insomnia or withdrawal symptoms after treatment discontinuation. Zolpidem 10 mg had significant effects on sleep latency, sleep duration, and sleep quality compared to placebo. However, a significantly greater incidence of withdrawal symptoms and a suggestion of sleep difficulty after treatment discontinuation (rebound insomnia) for all sleep measures was seen with zolpidem compared to placebo. There was no significant difference in the frequency of adverse events with active treatment compared to placebo. These results show that zaleplon provides effective treatment of insomnia with a favourable safety profile.