Summary
Estazolam enhances the effect of GABA on its receptor, while Zopiclone directly activates GABA.
Estazolam causes a reduction in non-REM sleep (which is deeper sleep), whereas Zopiclone does not 
Zopiclone provides better sleep quality.
Estazolam has a slow onset and long duration (6-8 hours), while Zopiclone acts quickly and lasts shorter (4-6 hours) Zopiclone is “milder.”
Main Text
The differences between Estazolam and Zopiclone are mainly reflected in the following aspects:
Drug Category
· Estazolam: belongs to the benzodiazepine class of drugs.
· Zopiclone: belongs to the non-benzodiazepine class, a cyclopyrrolone derivative.
Mechanism of Action
· Estazolam: works by binding to GABA receptors in the central nervous system, non-selectively agonizing different α subunits of the γ-aminobutyric acid type A receptor (GABAA), prolonging the transmission time of the GABA neurotransmitter, thereby inhibiting brain activity and exerting sedative, anxiolytic, muscle relaxant, and anticonvulsant effects.
· Zopiclone: acts on benzodiazepine receptors, enhancing the inhibitory effect of γ-aminobutyric acid, with greater selectivity for the α1 subunit on GABAA.
Duration of Effect
· Estazolam: reaches peak blood concentration 3 hours after oral administration, with a half-life of 10-24 hours, and the effect usually lasts 6-8 hours.
· Zopiclone: rapidly absorbed after oral administration, with peak blood concentration around 1 hour, a half-life of about 5 hours, and a typical duration of effect of 4-6 hours.
Indications
· Estazolam: mainly used for anxiety, insomnia, also for tension, fear, and anticonvulsant treatment.
· Zopiclone: mainly used for various types of insomnia, especially difficulties in falling asleep or sleep maintenance disorders.
Adverse Reactions
· Estazolam: common side effects include drowsiness, tension, dizziness, hangover, weakness, lower limb pain, back pain, and may also cause visual disturbances, ear pain, eye pain, taste alteration, photophobia, tinnitus; long-term use may impair memory, and abrupt discontinuation may cause withdrawal symptoms.
· Zopiclone: common side effects include bitter taste, dry mouth, dizziness, headache; occasionally hallucinations; a few people may exhibit complex sleep behaviors such as sleepwalking or sleep-driving.
Use in Special Populations
· Estazolam: use with caution in acute alcohol intoxication with central nervous system suppression, liver and kidney impairment, myasthenia gravis, acute or prone-to-occur angle-closure glaucoma attacks, severe chronic obstructive pulmonary disease, pregnant and breastfeeding women; elderly are more sensitive and should have dose adjustments.
· Zopiclone: use with caution in pregnant and breastfeeding women; due to high concentration in breast milk, breastfeeding women should avoid use; elderly are more sensitive and should have dose adjustments.
Addictiveness
· Estazolam: long-term use may lead to easier dependence.
· Zopiclone: relatively lower potential for addiction but still should avoid long-term high-dose use.