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Zolpidem CR effective for long-term use on as-needed basis among individuals with primary insomnia

Wednesday, December 12 2007 | Comments

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What's This? Zolpidem extended-release (zolpidem CR) appears to be an effective long-term treatment for chronic primary insomnia when taken on an as-needed basis, Phase IIIb data suggest.

In the double-blind study, researchers randomized 1,025 adults with chronic primary insomnia to take zolpidem CR 12.5 mg or placebo on an as-needed basis (3 to 7 times per week) for 6 months; 1,018 patients took >=1 dose of either zolpidem CR (n=669) or placebo (n=349).

Efficacy was assessed every fourth week of treatment with the Patient- and Clinician-rated Global Impression scales (PGI and CGI, respectively) and with daily morning questionnaires. The primary endpoint analysis focused on week 12 responses to the PGI item 1, which measures the extent to which the treatment aids sleep (possible responses: "helped me sleep," "did not affect my sleep," or "worsened my sleep").

The authors noted that 64.7% of the zolpidem CR group and 52.4% of the placebo group completed the study.

At week 12, 89.8% of patients treated with zolpidem CR reported that treatment aided their sleep compared with 51.4% of placebo-treated patients. The authors noted that, at each 4-week assessment during the entire 6-month treatment period, the zolpidem CR group showed significant improvement in PGI items 1 and 2 (a measure of a treatment's ability to induce sleep onset) relative to the placebo group (P<.0001 for both items at all time points).

For CGI responses at week 12, investigators rated 75% of zolpidem CR-treated patients as "much improved" or "very much improved" compared with 37.1% of placebo-treated patients. Differences between zolpidem CR and placebo in mean CGI scores were significant at each 4-week assessment during the entire treatment period (P<.0001).

Zolpidem CR was also associated with significantly greater reductions in mean wake after sleep onset (WASO) and significantly greater increases in total sleep time (TST) at each assessment during the 6-month treatment period (P<.0001 for both at each time point). At month 6, mean WASO had declined 68.27 min relative to baseline in the zolpidem CR group compared with 52.76 min in the placebo group; the corresponding increases in TST were 110.12 min and 84.57 min.

Morning questionnaire data showed that, relative to placebo-treated patients, zolpidem CR-treated patients reported significant improvement from baseline in the ability to concentrate (months 1 to 5, P<.0001; month 6, P=.0014) and a significant decrease from baseline in morning sleepiness (P<.0001 at all time points).

Treatment-emergent adverse events were reported by 63.2% of zolpidem CR-treated patients and 51.3% of placebo-treated patients. The most common adverse events were headache (10.5% vs 9.5%, respectively) and somnolence (5.7% vs 2.0%). (Krystal A, et al. Poster NR586.)

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