Eszopiclone
Eszopiclone is a non-benzodiazepine hypnotic used in adults for insomnia, including sleep onset and maintenance. It modulates GABA-A receptors with a moderate half-life that supports overnight sleep without long next-day residue.
- Chemical formula
- C17H17ClN6O3
- CAS number
- 138729-47-2
- ATC code
- N05CF04
- Molecular weight
- 388.81 g/mol
- Drug class
- Non-benzodiazepine hypnotic (Z-drug)
- Also known as
- S-zopiclone, Eszopiclona
What is it?
Eszopiclone is the active S-enantiomer of zopiclone and was approved in the United States in 2004. It is supplied as oral tablets and dispensed only on prescription. Compared with classical benzodiazepines, eszopiclone is structurally distinct, although it acts on the same GABA-A receptor complex. The molecule is intended for short to intermediate-term management of insomnia in adults whose sleep difficulties affect daytime function.
Mechanism of action
Eszopiclone is a positive allosteric modulator of the GABA-A receptor at a site close to the benzodiazepine binding site. It enhances inhibitory chloride conductance in central nervous system neurons, hyperpolarising them and producing sedation, sleep induction and prolongation of total sleep time. Selectivity profile across GABA-A subunits differs slightly from classic benzodiazepines, and the moderate half-life supports sleep maintenance.
Pharmacokinetics
Eszopiclone is rapidly absorbed orally, with peak plasma concentrations reached within one hour. Plasma protein binding is approximately 50% to 60%. The drug is metabolised in the liver primarily by CYP3A4 and CYP2E1 to inactive metabolites. The terminal half-life is approximately six hours, intermediate between short-acting and long-acting hypnotics, supporting both sleep onset and maintenance. Hepatic impairment, age and CYP3A4 inhibitors increase exposure.
Indications
Eszopiclone is approved in adults for the treatment of insomnia, including difficulty falling asleep and difficulty maintaining sleep. According to international guidelines, treatment should be limited in duration, with periodic reassessment, although clinical trials have evaluated longer-term use. Cognitive-behavioural therapy for insomnia is recommended as the first-line approach for chronic insomnia where available. Eszopiclone is not indicated for paediatric patients.
Safety profile
Common adverse effects include unpleasant taste, headache, dry mouth, drowsiness and dizziness. Complex sleep behaviours such as sleep-walking, sleep-eating and sleep-driving have been reported, in particular when combined with alcohol or other CNS depressants, and represent a contraindication to continued use. Anterograde amnesia and next-day impairment, especially of driving, are documented. According to the prescribing information, the lowest effective dose should be used, especially in elderly patients, and concomitant alcohol should be avoided.
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Frequently asked questions
How does eszopiclone differ from zolpidem? ▾
Both are non-benzodiazepine Z-drug hypnotics, but eszopiclone has a longer half-life (approximately 6 hours versus 2.5 hours for zolpidem), which supports both sleep onset and sleep maintenance. Zolpidem is more focused on sleep onset because of its shorter half-life. Tolerability and side-effect profiles overlap. According to the prescribing information, the choice between them is made by the prescriber based on the type of insomnia, comorbidity and response.
Is the bitter taste from eszopiclone normal? ▾
Yes. An unpleasant or metallic taste is one of the most common adverse effects of eszopiclone and is mentioned explicitly in the prescribing information. It is not considered dangerous and tends to be reported throughout treatment. Patients can take the tablet with water and ensure it is swallowed promptly. Persistent or severe taste disturbance should be discussed with the prescriber, who may adjust the regimen.
Can eszopiclone be used long-term? ▾
Eszopiclone is one of the few hypnotics evaluated in randomised trials lasting six months or more, which has supported approval without a strict label limit on duration in some markets. However, most clinical guidelines still recommend the shortest effective course, with periodic reassessment, because of dependence and complex sleep behaviour risks. According to the prescribing information, longer use should be supervised by the prescriber.
Are complex sleep behaviours associated with eszopiclone? ▾
Yes, like other Z-drugs and benzodiazepines. Reports include sleep-walking, sleep-eating, telephoning or driving while not fully awake, mostly in patients also using alcohol, other CNS depressants or higher than recommended doses. Although uncommon, the consequences can be serious. According to regulatory communications, any episode of complex sleep behaviour is a contraindication to continued use.
What are the main contraindications for eszopiclone? ▾
Eszopiclone is contraindicated in known hypersensitivity to the molecule and in patients with previous complex sleep behaviours while taking it. Caution is required in severe respiratory insufficiency, severe hepatic impairment, in older adults, in patients with substance use disorders and during pregnancy and breastfeeding. According to the prescribing information, the medical history must be reviewed by a clinician before any prescription.
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