Eszopiclone

Absorption

Eszopiclone is rapidly absorbed and the peak concentration is reached within about 1 hour after oral administration. The mean AUC after a 3 mg dose of eszopiclone was 278 ng/mL × h. The consumption of a high-fat has been shown to slow absorption. Steady-state concentrations of eszopiclone are reached within 24-48 hours.

Toxicity

The oral LD50 of eszopiclone in rats is 980 mg/kg and 3200 mg/kg in rabbits. Symptoms of overdose may include mental status changes and somnolence, demonstrating general exaggeration of the drug's pharmacological effects. Perform gastric lavage and offer supportive treatment if an overdose is suspected, including intravenous fluids as required. Flumazenil may be used. Vital signs should be closely monitored in addition to patient symptoms. Appropriate medical interventions should be employed. The possibility of an overdose with multiple drugs should be considered. Ensure to contact the local poison control center for the most updated management of hypnotic drug overdose.

Description

Eszopiclone is a non-benzodiazepine hypnotic agent indicated for the treatment of insomnia to induce sleep and for sleep maintenance. It has similar pharmacokinetic and pharmacodynamic parameters as the previously marketed non-benzodiazepine hypnotics zolpidem and zaleplon. However, unlike its predecessors, eszopiclone is not restricted to short-term treatment of insomnia. Clinical studies of up to 6 months of use show that patients do not develop tolerance to its effect. Eszopiclone is the (S)-enantiomer of zopiclone, which has been marketed as the racemic mixture in Europe for almost 20 years. These agents belong to the cyclopyrrolone class of drugs that act as agonists at the type A GABA receptor. Eszopiclone has approximately 50-fold higher binding affinity than its antipode (R)-zopiclone for GABA-A receptor (IC₅₀=21 and 1130 nM, respectively). In addition, the two enantiomers exhibit significant differences in their pharmacokinetic parameters and in vivo efficacy. In healthy volunteers, eszopiclone has 2-fold higher C_max and 2-fold greater elimination half-life than the (R)-enantiomer.The two most frequent adverse events associated with eszopiclone treatment are unpleasant taste and headache. Other less frequent side effects include somnolence, dry mouth, and nausea.

The Uses of Eszopiclone

Eszopiclone is the active stereoizomer of Zopiclone and belongs to the class of drug known as cyclopyrrones. It is a nonbenzodiazepine hypnotic agent used as a treatment for insomnia. This is a controlled substance (depressant) in the US but not in Canada.

Indications

Eszopiclone is indicated for the treatment of insomnia.

Background

Eszopiclone, marketed by Sepracor under the brand-name Lunesta, is a nonbenzodiazepine hypnotic drug used to treat insomnia. It is the active stereoisomer of zopiclone, belonging to the class of drugs known as cyclopyrrolones. Cyclopyrrolone drugs demonstrate high efficacy and low toxicity, offering a safer alternative to other drugs used for insomnia.
One major benefit of eszopiclone is that it is approved by the FDA for the long-term treatment of insomnia. This sets it apart from many other hypnotic sedatives, which are generally approved only for the relief of short-term (6-8 weeks) insomnia. Eszopiclone was initially approved by the FDA in 2004.

Pharmacokinetics

Eszopiclone rapidly induces sleep and decreases sleep latency. It also aids in the maintenance of sleep, preventing frequent awakenings. This drug has shown anticonvulsant and muscle relaxant properties in animals but is used in humans for its sedating effects.
Eszopiclone is a central nervous system depressant with various effects. These include changes in alertness and motor coordination and the risk of next morning impairment, increasing with the amount of eszopiclone administered. Exercise caution and advise against driving a motor vehicle or activities that require full mental alertness the next morning. Complex sleep behaviors may result from eszopiclone use. Eszopiclone should be discontinued in these cases. Avoid the use of alcohol and other CNS depressants when eszopiclone is administered. Advise patients to skip the eszopiclone dose if alcohol has been consumed before bed or during the evening. Use the smallest dose of eszopiclone as possible, especially in elderly patients, who may experience exaggerated drug effects. Though the potential for dependence and abuse with eszopiclone is lower than for other hypnotic drugs, this drug has been abused and is known to cause dependence.

Metabolism

Following oral administration, eszopiclone is extensively biotransformed and the major metabolites are S-desmethylzopiclone and zopiclone-N-oxide, which are largely inactive.. The enzymes involved in the metabolism of eszopiclone are CYP3A (the primary metabolizing enzyme), CYP2C8, and CYP2E1. The N-oxide derivative shows weak pharmacological activity in animals. The N-desmethyl metabolite is pharmacologically active.