Zopiclone
Zopiclone is a nonbenzodiazepine hypnotic of the cyclopyrrolone class, commonly grouped among the 'Z-drugs' that emerged in the 1980s and 1990s as treatments for insomnia.citation needed First introduced by Rhône-Poulenc in 1986, it acts on the GABA-benzodiazepine receptor complex despite being structurally unrelated to benzodiazepines or barbiturates. Zopiclone is reported to produce hallucinogenic effects when taken without the intent to sleep and is considered habit-forming. A persistent metallic taste is a commonly noted side effect.
Dosage & Duration
Dosage
Doses are population estimates that vary widely between individuals.
Duration
Subjective Effects
Legacy content. A statistically backed ontology from Mindstate Design Labs is coming soon.
Effects vary widely by individual, dose, and context.
Physical
The physical effects of zopiclone can be broken down into several components which progressively intensify proportional to dosage.
Cognitive
The general head space of zopiclone is described by many as one of intense sedation and decreased inhibition. It contains a large number of typical depressant cognitive effects.
Pharmacology
Pharmacodynamics
Zopiclone acts as a positive allosteric modulator at GABA-A receptors, binding at the benzodiazepine site on receptor subtypes containing α1, α2, α3, and α5 subunits.citation needed It functions as a full agonist at this site, enhancing the inhibitory actions of GABA at the chloride channel complex. Although one study found slight selectivity for the α1 and α5 subtypes, zopiclone is generally regarded as unselective across the four GABA-A subtypes it binds. It also shows agonist activity at the translocator protein.
Pharmacokinetics
Zopiclone is rapidly absorbed after oral administration with a bioavailability of approximately 75-80% and peak plasma concentrations within 1-2 hours.citation needed Plasma protein binding is weak, averaging 52-59%. It is extensively metabolized in the liver through decarboxylation (roughly 50% of a dose, with decarboxylated products excreted via the lungs), demethylation, and side chain oxidation.1 CYP3A4 and CYP2E1 have been identified as the principal hepatic enzymes involved, while hepatic microsomal enzymes have also been described as not significantly involved in clearance. The two major metabolites are N-desmethylzopiclone, which has been variably reported as pharmacologically active (with partial agonist and predominantly anxiolytic properties) or as inactive, and zopiclone-N-oxide, which has been described as both weakly active and inactive.citation needed The elimination half-life averages approximately 5 hours, ranging from 3.5 to 6.5 hours.
Caution
Use cautionThese combinations are not usually physically harmful, but may produce undesirable effects, such as physical discomfort or overstimulation. Extreme use may cause physical health issues. Synergistic effects may be unpredictable. Care should be taken when choosing to use this combination.
Tolerance
Tolerance timelines are rules of thumb, not exact schedules, and vary widely between individuals and use patterns.
Benzodiazepines, Other nonbenzodiazepine hypnotics (Z-drugs), Other GABA-A receptor positive allosteric modulators
Harm Potential
Addiction & Dependence
Psychological
ModerateZopiclone has significant potential for psychological dependence, with cases of addiction and habituation well-documented.citation needed Compulsive redosing and blackouts are reported, and animal self-administration studies suggest high reinforcing potential. Some evidence suggests it may be more addictive than benzodiazepines. Those with a history of substance misuse or mental health disorders are at increased risk.
Physical
ModeratePhysical dependence develops with prolonged use, even at therapeutic doses.citation needed Withdrawal symptoms similar to benzodiazepine withdrawal can occur even after gradual dose reduction, including significant agitation and anxiety that may require emergency medical attention. Convulsions are not typical at therapeutic doses and withdrawal is not considered life-threatening.
Toxicity
Long-term use has been associated with cognitive impairment including anterograde amnesia;citation needed impairments in body balance, standing steadiness, and motor coordination occur during intoxication and may persist the following day, with only partial tolerance developing to these effects over time.
Psychosis Risk
Hallucinations, confusion, nightmares, and paradoxical effects are reported rarely.citation needed Hallucinogenic effects may occur if the drug is taken while attempting to stay awake rather than for sleep.
Seizure Risk
Withdrawal symptoms from therapeutic doses do not typically present with convulsions and are therefore not considered life-threatening in this regard.citation needed
History & Culture
Zopiclone was developed by the French pharmaceutical company Rhône-Poulenc S.A. and first introduced to the market in 1986.citation needed Rhône-Poulenc has since become part of Sanofi, which remains the primary global manufacturer. Upon its release, zopiclone was marketed as…
Legality
By Country
CanadaPrescription only
SpainPrescription only
United KingdomPrescription only medicineReferences
Source Pages
Citations
- Critical pre-review report: Zopiclone. Expert Committee on Drug Dependence, 45th Meeting. (n.d.). https://cdn.who.int/media/docs/default-source/controlled-substances/45th-ecdd/zopiclone_draft.pdf1
- Health Canada Prescription Drug List. canada.ca (n.d.). https://www.canada.ca/content/dam/hc-sc/documents/services/drugs-health-products/drug-products/prescription-drug-list/notice-multiple-additions-18/pdl_list_fin_ord-eng.pdf1
- BIFIMED: Buscador de la Información sobre la situación de financiación de los medicamentos. sanidad.gob.es (n.d.). https://www.sanidad.gob.es/profesionales/medicamentos.do?cn=759452&metodo=verDetalle1
- Zopiclone 7.5mg film-coated tablets - Summary of Product Characteristics (SmPC). (n.d.). https://www.medicines.org.uk/emc/product/10590/smpc1
- 21 CFR 1308.14. ecfr.gov (n.d.). https://www.ecfr.gov/current/title-21/part-1308/section-1308.141
- Schedules of Controlled Substances: Placement of Zopiclone Into Schedule IV. Final rule.. (n.d.). https://pubmed.ncbi.nlm.nih.gov/15806735/1
Further Reading
Article Status
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Recent changes8 human edits · latest
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16 August 2026
Lyrea · Changed a word in Pharmacology › Pharmacokinetics
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24 January 2026
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
Josie Kins · Updated the article · also 1,4-Butanediol, 1B-LSD, 1cP-AL-LAD and 573 more
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