Because a substantial number of patients with insomnia take hypnotics
for extended periods, maintenance of effectiveness and the effects of
withdrawal following long-term use are critical issues. In this multic
enter, single-blind study, patients between 18 and 60 years of age (me
an, 42 years) received placebo for 4 to 7 nights, followed by 12 weeks
of nightly treatment with zolpidem 15 mg, followed by placebo for 1 w
ithdrawal week. If adverse events occurred, the study design allowed f
or a dose reduction to 10 mg. Efficacy was evaluated subjectively usin
g the Clinical Global Impression scale at the end of the placebo run-i
n period and at the end of weeks 2, 4, 8, and 12 and placebo week 13,
In addition, patients completed self-reports, describing their sleep b
efore each visit. Of the 229 patients who received zolpidem, 155 patie
nts completed all 12 weeks of treatment. Thirty-three patients had the
ir dose decreased from 15 mg to 10 mg at some time during the study. A
dverse effects led to withdrawal in only 8% of the patients initially
enrolled. The incidence of side effects was considerably higher with t
he 15-mg dose compared with the 10-mg dose. Despite the prolonged use
of higher than currently recommended doses of zolpidem, no evidence of
rebound insomnia was reported. In addition, there was no evidence of
drug tolerance throughout the 12 weeks of drug administration. In agre
ement with recommendations of numerous previous studies, the 10-mg dos
e was found to be safe during the 12-week treatment period.