Eszopiclone 2 mg · Tablets

The mechanism of action of eszopiclone as a hypnotic is unclear; however, its effect could be related to its interaction with GABA-receptor complexes at binding domains located close to or allosterically coupled to benzodiazepine receptors.

The pharmacokinetics of eszopiclone have been investigated in healthy subjects (adult and elderly) and in patients with hepatic disease or renal disease. In healthy subjects, the pharmacokinetic profile was examined after single doses of up to 7.5 mg and after once-daily administration of 1, 3, and 6 mg for 7 days. Eszopiclone is rapidly absorbed, with a time to peak concentration (t max) of approximately 1 hour and a terminal-phase elimination half-life (t 1/2) of approximately 6 hours. In healthy adults, eszopiclone does not accumulate with once-daily administration, and its exposure is dose-proportional over the range of 1 to 6 mg.

Absorption and Distribution — Eszopiclone is rapidly absorbed following oral administration. Peak plasma concentrations are achieved within approximately 1 hour after oral administration. Eszopiclone is weakly bound to plasma protein (52 to 59%). The large free fraction suggests that eszopiclone disposition should not be affected by drug-drug interactions caused by protein binding. The blood-to-plasma ratio for eszopiclone is less than one, indicating no selective uptake by red blood cells.

Metabolism — Following oral administration, eszopiclone is extensively metabolized by oxidation and demethylation. The primary plasma metabolites are (S)-zopiclone-N-oxide and (S)-N-desmethyl zopiclone; the latter compound binds to GABA receptors with substantially lower potency than eszopiclone, and the former compound shows no significant binding to this receptor. In vitrostudies have shown that CYP3A4 and CYP2E1 enzymes are involved in the metabolism of eszopiclone. Eszopiclone did not show any inhibitory potential on CYP450 1A2, 2A6, 2C9, 2C19, 2D6, 2E1, and 3A4 in cryopreserved human hepatocytes.

Elimination — After oral administration, eszopiclone is eliminated with a mean t 1/2of approximately 6 hours. Up to 75% of an oral dose of racemic zopiclone is excreted in the urine, primarily as metabolites. A similar excretion profile would be expected for eszopiclone, the S-isomer of racemic zopiclone. Less than 10% of the orally administered eszopiclone dose is excreted in the urine as parent drug.

Effect of Food — In healthy adults, administration of a 3 mg dose of eszopiclone after a high-fat meal resulted in no change in AUC, a reduction in mean C maxof 21%, and delayed t maxby approximately 1 hour. The half-life remained unchanged, approximately 6 hours. The effects of eszopiclone on sleep onset may be reduced if it is taken with or immediately after a high-fat/heavy meal.

Age — Compared with nonelderly adults, subjects 65 years and older had an increase of 41% in total exposure (AUC) and a slightly prolonged elimination of eszopiclone (t 1/2approximately 9 hours). C maxwas unchanged. Therefore, in elderly patients the dose should not exceed 2 mg.

Gender — The pharmacokinetics of eszopiclone in men and women are similar.

Race — In an analysis of data on all subjects participating in Phase 1 studies of eszopiclone, the pharmacokinetics for all races studied appeared similar.

Hepatic Impairment — Pharmacokinetics of a 2 mg eszopiclone dose were assessed in 16 healthy volunteers and in 8 subjects with mild, moderate, and severe liver disease. Exposure was increased 2-fold in severely impaired patients compared with the healthy volunteers. C maxand t maxwere unchanged. No dose adjustment is necessary for patients with mild-to-moderate hepatic impairment. Dose reduction is recommended for patients with severe hepatic impairment. Eszopiclone should be used with caution in patients with hepatic impairment [see Dosage and Administration ( 2.3)].

Renal Impairment — The pharmacokinetics of eszopiclone were studied in 24 patients with mild, moderate, or severe renal impairment. AUC and C maxwere similar in the patients compared with demographically matched healthy control subjects. No dose adjustment is necessary in patients with renal impairment, since less than 10% of the orally administered eszopiclone dose is excreted in the urine as parent drug.