Purpose: The pharmacology, pharmacokinetics, indications, clinical efficacy, adverse effects, drug interactions, dosing, and administration of eszopiclone are discussed.

Summary: The pharmacology of eszopiclone is not well understood. Eszopiclone is the S-isomer of racemic zopiclone. The relative bioavailability of oral racemic zopiclone is about 80%. Eszopiclone is rapidly absorbed after oral administration, with peak serum concentrations ranging from 1 to 1.3 hours. The efficacy of eszopiclone has been evaluated in healthy adults, including elderly patients, for the treatment of transient and chronic insomnia. Compared with placebo, eszopiclone has been shown to considerably reduce sleep induction and improve sleep maintenance, duration, quality, and depth, as well as next-day functioning. The most common adverse effects reported are unpleasant taste, headache, and dry mouth. Dosing should be individualized, and the lowest effective dose should be used to minimize the risk of adverse events. The recommended starting dosage for nonelderly patients is 2 mg immediately before bedtime, with adjustment to 3 mg if clinically indicated. Dosage adjustment is necessary in patients with severe hepatic disease and in those receiving concomitant potent cytochrome P-450 isoenzyme 3A4 inhibitors. No dosage adjustment is required for patients with renal dysfunction. The cost of eszopiclone is 3.70 dollars per tablet for all dosage strengths (1-, 2-, and 3-mg tablets).

Conclusion: Its favorable adverse-effect profile and approved labeling for the treatment of chronic insomnia makes eszopiclone a viable alternative for insomnia treatment. Published data are limited, however, and more clinical trials, including comparator studies, are needed to further evaluate the use of this drug.