Zopiclone

Products

Zopiclone is commercially available in tablet form (Imovane, auto-generics). It has been approved in many countries since 1993. In the United States, the pure -enantiomer eszopiclone is also available (Lunesta).

Structure and properties

Zopiclone (C17H17ClN6O3, Mr = 388.8 g/mol) is a racemate and belongs to the cyclopyrrolones. It exists as a white to slightly yellowish powder that is practically insoluble in water. Zopiclone has a bitter taste.

Effects

Zopiclone (ATC N05CF01) has sleep-inducing, depressant, anticonvulsant, and muscle relaxant properties. As with the benzodiazepines, the effects are due to binding to the GABAA receptor, although zopiclone has no obvious structural similarities to this group of drugs. Zopiclone, unlike the other Z-drugs, has a relatively long half-life of 5 hours.

Indications

For short-term treatment of sleep disorders. Zopiclone should be used only for severe symptoms.

Dosage

According to the drug label. The tablets are taken immediately before bedtime. Zopiclone should not be stopped suddenly or withdrawal symptoms may occur.

Contraindications

  • Hypersensitivity
  • Severe hepatic insufficiency
  • Severe respiratory insufficiency
  • Myasthenia gravis
  • Severe sleep apnea syndrome
  • Pre-existing severe psychiatric illness

Full precautions can be found in the drug label.

Interactions

Zopiclone is metabolized by CYP3A4. CYP2C8 also appears to be involved. CYP3A4 inhibitors may result in a significant increase in plasma concentration. Inducers reduce efficacy. Centrally depressant drugs such as opioids, antidepressants, neuroleptics, sleep aids, antianxiety agents, sedatives, antiepileptic drugs, older antihistamines, and alcohol may increase adverse effects.

Adverse effects

The most common adverse effect is a bitter taste after ingestion. Possible adverse effects include dry mouth, indigestion, vomiting, dizziness, headache, drowsiness on awakening, drowsiness, confusion, anterograde amnesia, sleepwalking, agitation, incoordination, central disturbances such as hallucinations, mood and personality changes. After discontinuation, withdrawal symptoms and sleep disturbances (“rebound insomnia“) may occur.