Zopiclone
Studies and references cited across this article, graded by evidence strength.
Inconclusive means the cited source neither confirms nor refutes the claim — a lower-confidence badge, not an error.
Data points an editor reviewed and accepted for publication.
Value Provenance
Dosing
oraltrace
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Threshold | 2 mg | 2 mg | high |
| Low | 3.5–5 mg | 3.5–5 mg | high |
| Common | 5–7.5 mg | 5–7.5 mg | high |
| Strong | 7.5–15 mg | 7.5–15 mg | high |
| Heavy | 15+ mg | 15+ mg | high |
| Editorial | Seed data values consistent with clinical dosing literature. Therapeutic dose 7.5 mg (standard adult), elderly starting dose 3.75 mg. Bioavailability ~77% from Gaillot 1987. Work-notes confirm high confidence for oral dosage. | ||
ReasoningReasoningSeed data values consistent with clinical dosing literature. Therapeutic dose 7.5 mg (standard adult), elderly starting dose 3.75 mg. Bioavailability ~77% from Gaillot 1987. Work-notes confirm high confidence for oral dosage. Evidence basis: controlled_human_study | |||
Duration
oral
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Onsettrace | 10–30 minutes | 10–30 minutes | high |
| Editorial | Seed data 10-30 minutes; consistent with Tmax 0.5-1h (Fernandez 1995). Bitter taste appears at ~24 min (Caille 1984), drowsiness follows rapidly. | ||
ReasoningReasoningSeed data 10-30 minutes; consistent with Tmax 0.5-1h (Fernandez 1995). Bitter taste appears at ~24 min (Caille 1984), drowsiness follows rapidly. Evidence basis: controlled_human_study | |||
| Peaktrace | 3–4 hours | 3–4 hours | high |
| Editorial | Seed data 3-4 hours for peak. Consistent with Tmax 0.5-1h and elimination half-life 3.5-6.5h. Peak sedation aligns with peak plasma concentrations. | ||
ReasoningReasoningSeed data 3-4 hours for peak. Consistent with Tmax 0.5-1h and elimination half-life 3.5-6.5h. Peak sedation aligns with peak plasma concentrations. Evidence basis: controlled_human_study | |||
| Totaltrace | 3.5–9 hours | 3.5–9 hours | high |
| Editorial | Seed data 3.5-9 hours total subjective experience. Consistent with elimination half-life of 3.5-6.5h in healthy adults. Range reflects inter-individual variability in metabolism. | ||
ReasoningReasoningSeed data 3.5-9 hours total subjective experience. Consistent with elimination half-life of 3.5-6.5h in healthy adults. Range reflects inter-individual variability in metabolism. Evidence basis: controlled_human_study | |||
| After effectstrace | 2–10 hours | 2–10 hours | high |
| Editorial | Work-notes specify up to 10 hours residual psychomotor/cognitive impairment documented at 7.5 mg (Patat 2001). Not subjective sedation but measurable performance deficits including driving impairment. | ||
ReasoningReasoningWork-notes specify up to 10 hours residual psychomotor/cognitive impairment documented at 7.5 mg (Patat 2001). Not subjective sedation but measurable performance deficits including driving impairment. Evidence basis: controlled_human_study | |||
Safety
Toxicity Profiletrace
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Acute | low | low | high |
| Chronic | moderate | moderate | high |
| Organs Affected | neuro, hepatic, pulmonary | neuro, hepatic, pulmonary | high |
| Editorial | Work-notes specify acute=low, chronic=moderate with high confidence. Published literature consistently characterizes zopiclone as having low acute toxicity as a single agent (Gunja 2013). Chronic toxicity moderate due to dependence and cognitive effects. Seed data 'Acute: high' contradicted published evidence and has been corrected. FLAG: Seed toxicity values needed editorial correction. | ||
ReasoningReasoningWork-notes specify acute=low, chronic=moderate with high confidence. Published literature consistently characterizes zopiclone as having low acute toxicity as a single agent (Gunja 2013). Chronic toxicity moderate due to dependence and cognitive effects. Seed data 'Acute: high' contradicted published evidence and has been corrected. FLAG: Seed toxicity values needed editorial correction. Evidence basis: controlled_human_study | |||
Dependence Profiletrace
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Physical | moderate | moderate | high |
| Psychological | moderate | moderate | high |
| Compulsive Redosing | low | low | high |
| Dose Escalation | low | low | high |
| Editorial | Work-notes specify moderate physical and psychological dependence, low-to-moderate compulsive redosing and dose escalation, with high confidence. Seed data 'extremely physically and psychologically addictive' overstated published evidence — corrected per Goa & Heel 1986, Schifano 2019 EudraVigilance data showing dependence risk equivalent to zolpidem but lower than benzodiazepines. | ||
ReasoningReasoningWork-notes specify moderate physical and psychological dependence, low-to-moderate compulsive redosing and dose escalation, with high confidence. Seed data 'extremely physically and psychologically addictive' overstated published evidence — corrected per Goa & Heel 1986, Schifano 2019 EudraVigilance data showing dependence risk equivalent to zolpidem but lower than benzodiazepines. Evidence basis: controlled_human_study | |||
Withdrawal Profiletrace
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Severity | moderate | moderate | medium |
| Symptoms | rebound insomnia, anxiety, abnormal dreams, nausea | rebound insomnia, anxiety, abnormal dreams, nausea | medium |
| Fatal | No | No | medium |
| Medical Supervision | Not required | Not required | medium |
| Editorial | Work-notes specify withdrawal onset within 1-2 days (inferred from half-life), severity moderate, duration days to weeks (class-level data). Symptoms from Monti & Pandi-Perumal 2007 and Pchelina 2017 comparative study. Zopiclone-specific withdrawal duration not formally characterized — class-level inference. | ||
ReasoningReasoningWork-notes specify withdrawal onset within 1-2 days (inferred from half-life), severity moderate, duration days to weeks (class-level data). Symptoms from Monti & Pandi-Perumal 2007 and Pchelina 2017 comparative study. Zopiclone-specific withdrawal duration not formally characterized — class-level inference. Evidence basis: controlled_human_study | |||
Tolerance Profiletrace
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Buildup | slow | slow | medium |
| Half-life | — | — | medium |
| Full Reset | 10.5 days | 10.5 days | medium |
| Cross-tolerances | benzodiazepines, zolpidem, zaleplon | benzodiazepines, zolpidem, zaleplon | medium |
| Editorial | Work-notes specify slow buildup (medium confidence) based on 17-week sustained efficacy data. Full reset 10.5 days proposed with low confidence per work-notes instruction — value unverified. Cross-tolerances confirmed via shared GABA-A benzodiazepine binding site. | ||
ReasoningReasoningWork-notes specify slow buildup (medium confidence) based on 17-week sustained efficacy data. Full reset 10.5 days proposed with low confidence per work-notes instruction — value unverified. Cross-tolerances confirmed via shared GABA-A benzodiazepine binding site. Evidence basis: controlled_human_study | |||
Effects & Profile
Contraindications
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| other Concurrent CNS depressant usetrace | absolute | absolute | high |
| Editorial | Work-notes list this as absolute contraindication with high confidence. Article prose and research output confirm polydrug overdose as principal fatality context (Gunja 2013, Kuitunen 1990). | ||
ReasoningReasoningWork-notes list this as absolute contraindication with high confidence. Article prose and research output confirm polydrug overdose as principal fatality context (Gunja 2013, Kuitunen 1990). | |||
| pregnancy breastfeeding Breastfeedingtrace | absolute | absolute | high |
| Editorial | Work-notes list as absolute contraindication, high confidence. Gaillot 1983 documented milk/plasma ratio ~0.80. Article prose confirms. | ||
ReasoningReasoningWork-notes list as absolute contraindication, high confidence. Gaillot 1983 documented milk/plasma ratio ~0.80. Article prose confirms. | |||
| hepatic Severe hepatic impairmenttrace | relative | relative | high |
| Editorial | Work-notes list as relative (dose reduction mandatory), high confidence. Gaillot 1987 provides PK data in hepatic insufficiency. | ||
ReasoningReasoningWork-notes list as relative (dose reduction mandatory), high confidence. Gaillot 1987 provides PK data in hepatic insufficiency. | |||
| age Elderly (>70 years)trace | relative | relative | high |
| Editorial | Work-notes list as relative (dose reduction mandatory), high confidence. Gaillot 1987 PK data; Glass 2005 meta-analysis on elderly risk. | ||
ReasoningReasoningWork-notes list as relative (dose reduction mandatory), high confidence. Gaillot 1987 PK data; Glass 2005 meta-analysis on elderly risk. | |||
| psychiatric History of substance use disordertrace | relative | relative | high |
| Editorial | Work-notes list as relative contraindication, high confidence. Schifano 2019 EudraVigilance data; Cimolai 2007 addiction service documentation. | ||
ReasoningReasoningWork-notes list as relative contraindication, high confidence. Schifano 2019 EudraVigilance data; Cimolai 2007 addiction service documentation. | |||
| respiratory Respiratory insufficiencytrace | relative | relative | medium |
| Editorial | Work-notes list as relative contraindication, medium confidence. Class-level inference from GABA-A PAM mechanism; zopiclone-specific respiratory data in compromised populations not identified. | ||
ReasoningReasoningWork-notes list as relative contraindication, medium confidence. Class-level inference from GABA-A PAM mechanism; zopiclone-specific respiratory data in compromised populations not identified. | |||
| other Driving or machinery operation within 10 hourstrace | relative | relative | high |
| Editorial | Work-notes list as relative contraindication, high confidence. Patat 2001 documented 10h impairment window; Karhana 2025 confirms zopiclone as driving impairment standard. | ||
ReasoningReasoningWork-notes list as relative contraindication, high confidence. Patat 2001 documented 10h impairment window; Karhana 2025 confirms zopiclone as driving impairment standard. | |||
| pregnancy breastfeeding Pregnancytrace | relative | relative | medium |
| Editorial | Work-notes list as relative contraindication, medium confidence. No human pregnancy studies; fetal exposure inferred from breast milk data (Gaillot 1983). | ||
ReasoningReasoningWork-notes list as relative contraindication, medium confidence. No human pregnancy studies; fetal exposure inferred from breast milk data (Gaillot 1983). | |||
| neurological Myasthenia gravistrace | relative | relative | low |
| Editorial | Work-notes list class-level contraindications including myasthenia gravis. Inferred from GABA-A PAM class; no zopiclone-specific studies. | ||
ReasoningReasoningWork-notes list class-level contraindications including myasthenia gravis. Inferred from GABA-A PAM class; no zopiclone-specific studies. | |||
Timeline Phases
oral
| Field | Published | AI Proposed | Confidence |
|---|---|---|---|
| Afterglowtrace | 7200–14400 sec(i=0.15) | 7200–14400 sec(i=0.15) | high |
| Editorial | Work-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. | ||
ReasoningReasoningWork-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. Evidence basis: controlled_human_study | |||
| Onsettrace | 600–1800 sec(i=0.40) | 600–1800 sec(i=0.40) | high |
| Editorial | Work-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. | ||
ReasoningReasoningWork-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. Evidence basis: controlled_human_study | |||
| Peaktrace | 1800–14400 sec(i=1.00) | 1800–14400 sec(i=1.00) | high |
| Editorial | Work-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. | ||
ReasoningReasoningWork-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. Evidence basis: controlled_human_study | |||
| Resolutiontrace | 7200–10800 sec(i=0.30) | 7200–10800 sec(i=0.30) | high |
| Editorial | Work-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. | ||
ReasoningReasoningWork-notes specify onset (10–30 min), peak (0.5–4h), resolution (4–6h), afterglow (6–10h) for oral ROA. Duration values derived from Fernandez 1995 PK data (Tmax 0.5–1h, t½ 3.5–6.5h) and Patat 2001 residual impairment data (up to 10h). Afterglow driving advisory from work-notes verbatim. Evidence basis: controlled_human_study | |||
Dose Tier Summaries
Mild sedation and growing drowsiness at 3.5–5 mg oral, corresponding to the elderly and hepatically impaired starting dose range. Sleep onset is facilitated but not guaranteed. The bitter-metallic taste is prominent and consistent. Thought deceleration and mild analysis suppression may be noticed. Physical effects include mild muscle relaxation and bodily heaviness. Motor control impairment is minimal but present. Some individuals report mild dizziness. Dry mouth may occur. Mild next-morning grogginess is possible, particularly in slow metabolizers or elderly individuals. Functional impairment the following day is generally subclinical but cannot be excluded.
Work-notes specify 3.5–5 mg light range. Corresponds to clinical elderly starting dose (3.75 mg). Effects profile drawn from clinical trial literature and pharmacokinetic data.
ReasoningReasoning
Work-notes specify 3.5–5 mg light range. Corresponds to clinical elderly starting dose (3.75 mg). Effects profile drawn from clinical trial literature and pharmacokinetic data.
Evidence basis: controlled_human_study
Minimal sedation at 2 mg oral — a subtherapeutic dose below the elderly starting dose of 3.75 mg. The characteristic bitter-metallic taste appears within minutes as the first perceptible signal, accompanied by subtle drowsiness without reliable sleep induction. Physical effects are negligible at this level. Mild heaviness in the limbs may be noticed by sensitive individuals, but motor control and coordination remain intact. No meaningful muscle relaxation or respiratory effects. This dose is insufficient for clinical sleep induction and serves primarily as a perceptual threshold marker. Next-morning residual effects are unlikely at this level.
Work-notes specify 2 mg threshold with detailed description. Consistent with clinical literature — therapeutic dose is 7.5 mg, elderly starting dose 3.75 mg.
ReasoningReasoning
Work-notes specify 2 mg threshold with detailed description. Consistent with clinical literature — therapeutic dose is 7.5 mg, elderly starting dose 3.75 mg.
Evidence basis: controlled_human_study
Reliable sleep induction at 5–7.5 mg oral — the standard therapeutic range. Full hypnotic effect with preserved slow-wave sleep architecture. Sedation is pronounced and rapid, with most users falling asleep within 30 minutes. The bitter-metallic taste is universal. Thought deceleration and analysis suppression are moderate. Anterograde amnesia is possible at the upper end of this range. Physical effects include moderate muscle relaxation, motor control impairment sufficient to affect balance and coordination, and mild dizziness. Respiratory effects are negligible at this dose in healthy individuals. Residual psychomotor impairment is documented up to 10 hours post-dose at 7.5 mg. Do not drive or operate machinery for at least 8–10 hours after dosing, even if subjective drowsiness has resolved.
Work-notes specify 5–7.5 mg common range. Standard therapeutic dose is 7.5 mg. Patat 2001 documented 10h residual impairment. Sleep architecture data from multiple polysomnographic studies.
ReasoningReasoning
Work-notes specify 5–7.5 mg common range. Standard therapeutic dose is 7.5 mg. Patat 2001 documented 10h residual impairment. Sleep architecture data from multiple polysomnographic studies.
Evidence basis: controlled_human_study
Pronounced sedation at 7.5–15 mg oral, exceeding the standard therapeutic dose. Amnesia becomes increasingly likely and may be substantial — users may perform actions with no subsequent memory. Motor control impairment is significant, with marked ataxia and balance disruption. Disinhibition and emotional lability may emerge, particularly in elderly patients. Risk of complex sleep behaviors increases at this range — sleepwalking, sleep-eating, and other parasomnias have been documented across the Z-drug class. Confusion and cognitive impairment are prominent. Mild euphoria is reported by some users. This dose range exceeds clinical recommendations and carries meaningfully elevated risk. Residual impairment will extend well beyond 10 hours. Functional capacity the following day is likely compromised.
Work-notes specify 7.5–15 mg strong range. Effects at supratherapeutic doses drawn from Gunja 2013 Z-drug review, clinical case reports, and pharmacovigilance data. Complex sleep behavior risk from Chen 2013.
ReasoningReasoning
Work-notes specify 7.5–15 mg strong range. Effects at supratherapeutic doses drawn from Gunja 2013 Z-drug review, clinical case reports, and pharmacovigilance data. Complex sleep behavior risk from Chen 2013.
Evidence basis: published_case_series
Deep sedation or stupor at 15+ mg oral — well into overdose territory. Significant anterograde amnesia is expected, with extensive memory gaps covering hours of activity. Motor control impairment is severe, with high fall risk. Confusion and delirium may occur. Delusions of sobriety are possible, leading to dangerous decision-making. Respiratory depression risk increases at this level, particularly with any co-ingestant. Nausea and vomiting may occur. The combination of profound sedation with paradoxical behavioral activation can produce complex, dangerous behaviors with no subsequent recall. This dose requires medical monitoring. Flumazenil can reverse sedation if needed. Fatality risk as a single agent remains low, but rises substantially with concurrent CNS depressants. Do not combine with alcohol, opioids, or benzodiazepines under any circumstances.
Work-notes specify 15+ mg heavy range as overdose territory. Gunja 2013 describes clinical overdose presentations. Flumazenil reversal documented. Polydrug fatality context from forensic case series.
ReasoningReasoning
Work-notes specify 15+ mg heavy range as overdose territory. Gunja 2013 describes clinical overdose presentations. Flumazenil reversal documented. Polydrug fatality context from forensic case series.
Evidence basis: published_case_series
History
backfill Jun 4, 2026
Historical versions do not record which reviewer approved them; editorial accountability is recorded per value in the database and in the publication ledger going forward.
Sources
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- [2]strongZopiclone. A review of its pharmacodynamic and pharmacokinetic properties and therapeutic efficacy as an hypnoticGoa KL, Heel RC · 1986 · Drugspubmed 287497412 claims checked4 verified8 inconclusive
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- [5]moderateMolecular actions of (S)-desmethylzopiclone (SEP-174559), an anxiolytic metabolite of zopicloneFleck MW · 2002 · Journal of Pharmacology and Experimental Therapeuticspubmed 121307237 claims checked7 verified
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Claim Verification
Citation-bearing claims in this article were checked by an AI model against the abstract of the source they cite — every safety-critical claim, plus a sample of the rest. Verdicts below are model-issued, not human-issued; when an editor overrides a verdict, the override is recorded alongside it. Claims whose source does not support them are flagged for editorial review.
summary9 claims3verified6inconclusive
inconclusiveMarketed as Imovane and Zimovane, it produces rapid sleep induction at a standard oral dose of 7.5 mg, with a total duration of 3.5–9 hours driven by an elimination half-life of 3.5–6.5 hours in healthy adults[1]model confidence 70%
The abstract directly confirms the elimination half-life of 3.5–6.5 hours, but brand names (Imovane/Zimovane), the 7.5 mg standard dose, and total duration of 3.5–9 hours are not mentioned in the abstract. Those details would be in the full text of this comprehensive PK review.
Terminal elimination half-life 3.5-6.5 hours.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone was developed by Rhône-Poulenc S.A. as the first member of the cyclopyrrolone class, patented in 1972 and first approved in France in 1986[2]model confidence 70%
Abstract confirms zopiclone as 'first of the cyclopyrrolones, a new class of psychotherapeutic agents,' which supports part of the claim. However, Rhône-Poulenc S.A., the 1972 patent, and 1986 French approval are not in the abstract; they would be in the full text of this landmark review.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone is authorized in Canada, Australia, and much of Europe but is not marketed in the United States, where only eszopiclone received FDA approval in 2004[3]model confidence 65%
The abstract covers eszopiclone and mentions its availability in Europe and Canada, but does not address zopiclone's US regulatory status, Australia, or the specific FDA approval year of 2004 for eszopiclone.
Eszopiclone is the S-isomer of racemic zopiclone, available in Europe, Canada, and Latin America since 1987.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe compound was placed in Schedule IV of the US Controlled Substances Act in 2005.[4]model confidence 95%
The abstract is the actual DEA final rule text, directly confirming zopiclone's placement into Schedule IV of the Controlled Substances Act. The year 2005 is in the SCOPE of this regulatory document.
DEA places zopiclone, including its salts, isomers and salts of isomers into Schedule IV of the Controlled Substances Act.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedUnlike the highly α1-selective zolpidem, racemic zopiclone potentiates currents without marked selectivity between α1-, α2-, and α3-containing receptor assemblies, and requires the γ2 subunit for activity[5]model confidence 97%
Abstract directly confirms non-selectivity across alpha1, alpha2, alpha3-bearing receptors, gamma2 subunit requirement, and that these effects are shared with racemic zopiclone.
Not selective between alpha1, alpha2, alpha3-bearing receptors. Requires gamma2 subunit. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveThe primary experiential signature is rapid sedation with preserved slow-wave sleep architecture, accompanied by a characteristic bitter-metallic taste appearing within 24 minutes of dosing[6]model confidence 65%
The abstract confirms bitter taste at 24 min post-dose, but does not address preserved slow-wave sleep architecture or rapid sedation. This is a PK/drug-interaction study, not a sleep architecture study.
Bitter taste reported at 24 min post-dose.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedResidual psychomotor and cognitive impairment persists up to 10 hours post-dose at the standard 7.5 mg oral dose[7]model confidence 98%
Abstract directly and explicitly confirms that zopiclone 7.5mg shows significant detrimental residual effects on psychomotor/cognitive functions up to 10h after dose.
Zopiclone 7.5mg showed significant detrimental residual effects on psychomotor/cognitive functions up to 10h after dose administration.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveDependence develops with prolonged use, though published literature consistently characterizes zopiclone's dependence potential as lower than that of benzodiazepines[2]model confidence 60%
Abstract does not mention dependence potential or comparison to benzodiazepines in this regard. As a comprehensive early review, this information would likely be in the full text, but cannot be confirmed from the abstract alone.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveNo human LD₅₀ data exist; deaths from zopiclone alone are rare, with fatality predominantly associated with polydrug overdose[8]model confidence 65%
Abstract is a comprehensive forensic toxicology review covering overdose and fatalities, which is the right scope for this claim, but the specific assertions about LD50 absence and rarity of solo deaths are not detailed in the abstract.
Comprehensive forensic toxicology review of Z-drugs including zopiclone. Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
history4 claims1verified3inconclusive
verifiedThe clinical program demonstrated comparable hypnotic efficacy to established benzodiazepines with the claimed advantages of preserved slow-wave sleep architecture and lower next-day residual sedation at the standard 7.5 mg dose.[2]model confidence 90%
Abstract directly confirms comparable efficacy to nitrazepam, flurazepam, triazolam, temazepam, and minimal next-day impairment. REM sleep unaffected is also noted, consistent with SWS preservation claim.
Comparable efficacy to nitrazepam 5mg, flurazepam 15-30mg, triazolam 0.5mg, temazepam 20mg. Minimal next-day impairment. REM sleep substantially unaffected.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveA prototype synthesis was patented in 1972, and the compound was described as the first member of the cyclopyrrolone chemical class — a novel scaffold bearing no structural relationship to the barbiturate, benzodiazepine, or imidazopyridine families[2]model confidence 65%
Abstract confirms zopiclone is first of the cyclopyrrolones, supporting the structural novelty claim. Patent year of 1972 and specific structural comparisons are not in the abstract.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveThe first human pharmacokinetic and metabolism studies were published in 1982–1983, establishing the core absorption, distribution, and elimination parameters that guided subsequent clinical development.[9]model confidence 65%
Abstract describes early PK data (bioavailability, half-life, clearance) consistent with foundational PK characterization, but publication year of 1982–1983 is not stated in the abstract.
Earlier version of PK data: bioavailability >75%, t1/2 4-5h, total body clearance 300ml/min.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveThe US Food and Drug Administration approved eszopiclone (Lunesta) in December 2004 for insomnia treatment — the first hypnotic approved in the United States without a limitation on duration of use[3]model confidence 60%
Abstract covers eszopiclone pharmacology but does not mention the FDA approval date, Lunesta brand name, or the claim about being the first without a duration limitation.
Eszopiclone is the S-isomer of racemic zopiclone, available in Europe, Canada, and Latin America since 1987.
checked by claude-sonnet-4-6 · May 9, 2026
chemistry2 claims2verified
verifiedZopiclone is the prototypical member of the cyclopyrrolone class, a family of heterocyclic compounds structurally unrelated to benzodiazepines, barbiturates, or the imidazopyridine scaffold shared by zolpidem[2]model confidence 88%
Abstract directly confirms zopiclone is first of the cyclopyrrolones, a new class — implying structural novelty and distinction from existing drug classes.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe carboxylate linkage is metabolically labile, providing the primary site for hepatic decarboxylation — the dominant metabolic route, accounting for over 50% of the administered dose in animal models.[10]model confidence 90%
Abstract directly confirms decarboxylation as the dominant metabolic route at >50% in this multi-species study.
Major metabolic routes: decarboxylation >50%, N-demethylation and N-oxidation >30%.
checked by claude-sonnet-4-6 · May 9, 2026
pharmacology21 claims15verified4partial2inconclusive
verifiedCYP3A4 is the principal cytochrome P450 isoform involved in hepatic metabolism.[14]model confidence 90%
Abstract directly confirms that CYP3A4 plays an important role in zopiclone's N-demethylation, N-oxidation, and decarboxylation.
CYP3A4 plays important role.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedZopiclone is a positive allosteric modulator (PAM) of ionotropic GABA-A receptors, binding at the benzodiazepine site located at the interface of the α and γ₂ subunits[2]model confidence 80%
Abstract confirms binding at the benzodiazepine receptor complex, which is consistent with the GABA-A benzodiazepine site claim. The specific α/γ₂ subunit interface is not stated, but the BZD receptor complex binding is the core of the claim.
Binding thought to occur to benzodiazepine receptor complex.
checked by claude-sonnet-4-6 · May 9, 2026
partialZopiclone and its active S-enantiomer show preferential interaction with omega-1 (α1-containing) receptors over omega-2 (α2/α3-containing) subtypes, though this selectivity is substantially less pronounced than that of zolpidem[11]model confidence 72%
Abstract confirms Z-drugs interact preferentially with omega-1 over omega-2 receptors, supporting the first part of the claim. However, the specific comparison that zopiclone's selectivity is 'substantially less pronounced than zolpidem' is not addressed — the abstract treats all Z-drugs together.
Interact preferentially with omega-1 (alpha-1) receptors vs omega-2 for BZDs.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedFunctional electrophysiology studies demonstrated that racemic zopiclone and the S-desmethylzopiclone metabolite (SEP-174559) potentiate GABA-A currents across α1-, α2-, and α3-containing assemblies without meaningful subtype selectivity, and that potentiation strictly requires the γ2 subunit.[5]model confidence 99%
Abstract directly confirms all elements: no selectivity between alpha1/2/3 receptors, gamma2 subunit requirement, and that these effects are shared with racemic zopiclone.
Not selective between alpha1, alpha2, alpha3-bearing receptors. Requires gamma2 subunit. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
partialStructural analysis of eszopiclone at the benzodiazepine binding pocket revealed a binding mode dependent on specific hydrogen bonds at γ2 loops D and E and α1 loops A, B, and C — mechanistically distinct from zolpidem, which relies primarily on hydrophobic shape complementarity within the pocket.[12]model confidence 78%
Abstract confirms hydrogen bond-dependent binding at gamma2 loop E and alpha1 loop C, and zolpidem shape-recognition mechanism. However, the claim additionally specifies gamma2 loop D and alpha1 loops A and B, which are not mentioned in the abstract — these may be overstated.
Mutations in gamma2 loop E and alpha1 loop C differentially affected ligand affinity. Eszopiclone docking: single model stabilized by several hydrogen bonds. Zolpidem: three orientations with few polar interactions.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedSecondary pharmacological actions include noncompetitive inhibition of nicotinic acetylcholine (nACh) receptors and inhibition of NMDA receptor currents at micromolar concentrations in vitro[5]model confidence 92%
Abstract directly confirms noncompetitive nACh receptor inhibition and NMDA receptor current inhibition, shared with racemic zopiclone. The 'micromolar concentrations' qualifier is not in the abstract but core mechanism is confirmed.
Also inhibits nicotinic acetylcholine receptors (noncompetitively) and NMDA receptor currents. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone also exhibits anticonvulsant, muscle relaxant, and anxiolytic activity in animal models.[2]model confidence 55%
The abstract does not mention anticonvulsant, muscle relaxant, or anxiolytic activity. As a comprehensive pharmacodynamic review, this information would likely appear in the full text, but cannot be verified from the abstract.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedZopiclone is rapidly absorbed following oral administration, reaching peak plasma concentrations (T_max) within 0.5–1 hour in healthy young adults[1]model confidence 80%
Abstract explicitly confirms rapid absorption after oral administration. Specific T_max of 0.5–1h is not stated but consistent with 'rapidly absorbed'; full text of this comprehensive PK review would contain the T_max data.
After oral administration, zopiclone is rapidly absorbed, with a bioavailability of approximately 80%.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAbsolute oral bioavailability is approximately 77%, reflecting a first-pass hepatic extraction of 20–25%[13]model confidence 95%
Abstract directly confirms absolute bioavailability of 77% and first-pass effect of 20%. The claimed range of 20–25% is consistent with the abstract's reported 20% value.
First-pass effect of 20%, absolute bioavailability 77%.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedProtein binding ranges from 45–80% across published studies.[1]model confidence 99%
Abstract directly states 'Plasma protein binding 45-80%', exactly matching the claim.
Plasma protein binding 45-80%.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedProtein binding ranges from 45–80% across published studies.[10]model confidence 85%
Abstract reports plasma protein binding ~45%, which is the lower bound of the stated range. The claim is about the range 'across published studies,' and this study represents one data point at the lower end of that range.
Plasma protein binding ~45%.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveThe volume of distribution ratio (Vdc/Vdt) is 3.2[13]model confidence 80%
Abstract does not mention volume of distribution or any Vdc/Vdt ratio. The abstract covers Tmax, bioavailability, half-life, and liver/elderly PK but not distribution volumes.
Tmax 0.5h in young volunteers. First-pass effect of 20%, absolute bioavailability 77%. Half-life 5.1h.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedHepatic metabolism proceeds through three primary routes: (1) decarboxylation, accounting for greater than 50% of the dose and producing CO₂ exhaled via the lungs; (2) N-demethylation, yielding the inactive N-desmethylzopiclone metabolite; and (3) N-oxidation, producing the pharmacologically active N-oxide metabolite[1]model confidence 97%
Abstract directly confirms all three metabolic routes: ~50% decarboxylation and exhalation, inactive N-demethylated derivative, and active N-oxide metabolite.
Metabolites: inactive N-demethylated derivative and active N-oxide metabolite. ~50% decarboxylated and exhaled.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedHepatic metabolism proceeds through three primary routes: (1) decarboxylation, accounting for greater than 50% of the dose and producing CO₂ exhaled via the lungs; (2) N-demethylation, yielding the inactive N-desmethylzopiclone metabolite; and (3) N-oxidation, producing the pharmacologically active N-oxide metabolite[10]model confidence 93%
Abstract directly confirms decarboxylation >50% and N-demethylation and N-oxidation. Activity characterizations (inactive/active) are not specified in this abstract but are confirmed in citation [1].
Major metabolic routes: decarboxylation >50%, N-demethylation and N-oxidation >30%.
checked by claude-sonnet-4-6 · May 9, 2026
partialCYP3A4 is the principal cytochrome P450 isoform involved in hepatic metabolism.[15]model confidence 78%
Abstract states zopiclone is biotransformed by 'multiple CYP isozymes in addition to CYP3A4,' confirming CYP3A4 involvement but not confirming it as 'principal.' The phrasing suggests other isozymes are also meaningfully involved.
Zopiclone biotransformed by multiple CYP isozymes in addition to CYP3A4.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe elimination half-life in healthy young adults is 3.5–6.5 hours, with controlled studies reporting a mean of approximately 5.1 hours[1]model confidence 97%
Abstract directly confirms terminal elimination half-life of 3.5–6.5 hours, matching the stated range exactly.
Terminal elimination half-life 3.5-6.5 hours.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe elimination half-life in healthy young adults is 3.5–6.5 hours, with controlled studies reporting a mean of approximately 5.1 hours[13]model confidence 97%
Abstract directly reports half-life of 5.1h in young volunteers, confirming the stated mean.
Half-life 5.1h.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe elimination half-life in healthy young adults is 3.5–6.5 hours, with controlled studies reporting a mean of approximately 5.1 hours[6]model confidence 88%
Abstract reports elimination half-life of 3.8h, which falls within the stated range of 3.5–6.5 hours, supporting the claim.
Elimination half-life 3.8h.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedLess than 7% of the dose is excreted unchanged in urine; total body clearance is approximately 300 mL/min, with renal clearance contributing only ~10 mL/min[10]model confidence 90%
Abstract directly confirms total body clearance of 300 mL/min and <7-10% excreted unchanged. Renal clearance of ~10 mL/min is not stated but the very low unchanged renal excretion is consistent.
Total body clearance 300ml/min. <7-10% excreted unchanged.
checked by claude-sonnet-4-6 · May 9, 2026
partialZopiclone is detectable in saliva, with the characteristic bitter taste appearing at approximately 24 minutes post-dose when saliva concentrations reach ~50 ng/mL[6]model confidence 75%
Abstract confirms bitter taste appearing at 24 minutes post-dose. The specific saliva concentration threshold of ~50 ng/mL is not mentioned in the abstract and cannot be verified from it.
Bitter taste reported at 24 min post-dose.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe compound is excreted in breast milk with a milk/plasma ratio of approximately 0.80.[10]model confidence 99%
Abstract directly states milk/plasma ratio ~0.80 in nursing mothers.
Milk/plasma ratio ~0.80 in nursing mothers.
checked by claude-sonnet-4-6 · May 9, 2026
receptor pharmacology3 claims3verified
verifiedFunctional electrophysiology data demonstrated that racemic zopiclone and the S-desmethylzopiclone metabolite potentiate GABA-evoked currents across α1β2γ2, α2β2γ2, and α3β2γ2 receptor configurations without significant subtype selectivity[5]model confidence 97%
Abstract directly confirms no selectivity between alpha1, alpha2, alpha3-bearing receptors with gamma2 requirement, and that effects are shared with racemic zopiclone.
Not selective between alpha1, alpha2, alpha3-bearing receptors. Requires gamma2 subunit. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe potentiation is strictly γ2-dependent: no modulation occurs at receptors lacking the γ2 subunit[5]model confidence 99%
Abstract directly states 'Requires gamma2 subunit.'
Requires gamma2 subunit.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAt micromolar concentrations in vitro, zopiclone and S-desmethylzopiclone noncompetitively inhibit nicotinic acetylcholine receptor currents and reduce NMDA receptor-mediated currents[5]model confidence 92%
Abstract directly confirms noncompetitive nACh inhibition and NMDA current inhibition shared with racemic zopiclone. Micromolar concentrations are not specified in the abstract but the mechanism is confirmed.
Also inhibits nicotinic acetylcholine receptors (noncompetitively) and NMDA receptor currents. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
neuroscience4 claims4inconclusive
inconclusiveThe sedative and hypnotic effects are mediated primarily through α1-containing GABA-A receptors concentrated in cortical and thalamic regions, while the broader α2/α3 engagement contributes to anxiolytic and muscle relaxant properties.[2]model confidence 55%
Abstract confirms BZD receptor complex binding but does not address subunit-specific mechanisms or regional distribution in the abstract. These mechanistic details are not in this early review's abstract.
Binding thought to occur to benzodiazepine receptor complex.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone's preservation of slow-wave sleep, in contrast to benzodiazepines, may reflect its distinct binding mode at the benzodiazepine pocket, though no direct mechanistic explanation for this differential sleep architecture effect has been published.[12]model confidence 60%
Abstract covers structural differences in binding modes between eszopiclone and zolpidem but does not address SWS preservation or sleep architecture in relation to binding mode.
Suggests eszopiclone relies on specific residue interactions while zolpidem relies on shape recognition.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveResidual next-day impairment — psychomotor slowing, impaired highway driving performance, and anterograde amnesia — correlates with persistent receptor occupancy beyond the period of subjective sedation[16]model confidence 65%
Abstract confirms measurement of next-morning driving, psychomotor, and memory performance — the right scope — but does not address receptor occupancy as the mechanism.
Measured next-morning driving performance, memory functioning, psychomotor performance, and mood.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveWhy does zopiclone preserve slow-wave sleep while benzodiazepines suppress it, given that both act at the same allosteric site? The different hydrogen bonding patterns identified in structural studies provide a hypothesis but no functional explanation has been demonstrated.[12]model confidence 60%
Abstract covers structural binding mode differences between eszopiclone and zolpidem but does not address SWS preservation or the benzodiazepine comparison on sleep architecture.
Suggests eszopiclone relies on specific residue interactions while zolpidem relies on shape recognition.
checked by claude-sonnet-4-6 · May 9, 2026
pharmacokinetic detail5 claims2verified3partial
partialMetabolic clearance decreases, resulting in elevated bioavailability (up to ~168% of the young-adult value in the oldest subjects studied), and the elimination half-life extends to approximately 8.1 hours[13]model confidence 75%
Abstract directly confirms half-life extends to 8.1h in elderly over 74. The specific bioavailability increase to ~168% of young-adult value is not in the abstract and cannot be verified.
In elderly over 74: half-life up to 8.1h.
checked by claude-sonnet-4-6 · May 9, 2026
partialSevere hepatic impairment delays T_max to approximately 3.5 hours, increases bioavailability to ~97%, and prolongs the elimination half-life to ~8.4 hours due to reduced metabolic clearance[13]model confidence 75%
Abstract directly confirms half-life prolongation to 8.4h in liver insufficiency. T_max delay to 3.5h and bioavailability increase to ~97% are not mentioned in the abstract.
In liver insufficiency: prolonged t1/2 8.4h.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedDecarboxylation is the dominant pathway in animal models, accounting for over 50% of the administered dose, with the liberated CO₂ exhaled via the lungs[10]model confidence 93%
Abstract directly confirms decarboxylation >50% in this multi-species study. CO₂ exhalation is the expected product of decarboxylation.
Major metabolic routes: decarboxylation >50%.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedN-demethylation produces the inactive N-desmethylzopiclone metabolite, and N-oxidation yields the pharmacologically active N-oxide metabolite[1]model confidence 99%
Abstract directly states 'inactive N-demethylated derivative and active N-oxide metabolite.'
Metabolites: inactive N-demethylated derivative and active N-oxide metabolite.
checked by claude-sonnet-4-6 · May 9, 2026
partialCYP3A4 is the principal cytochrome P450 isoform involved, with additional CYP enzymes contributing to metabolism but not yet individually characterized.[15]model confidence 78%
Abstract confirms multiple CYP isozymes including CYP3A4 are involved, and that other CYPs besides CYP3A4 contribute. However, the claim that CYP3A4 is 'principal' is not supported — the abstract states multiple isozymes are involved without indicating primacy.
Zopiclone biotransformed by multiple CYP isozymes in addition to CYP3A4.
checked by claude-sonnet-4-6 · May 9, 2026
clinical evidence9 claims7verified2inconclusive
inconclusiveSimilar long-term findings have been reported for eszopiclone at 3 mg for up to 12 months[3]model confidence 65%
Abstract covers eszopiclone PK and side effects but does not mention 12-month efficacy data. This specific long-term duration claim cannot be verified from the abstract.
Eszopiclone is the S-isomer of racemic zopiclone, available in Europe, Canada, and Latin America since 1987.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA triple-blind, placebo-controlled trial (NCT03075241) in 62 patients with Alzheimer's disease compared zopiclone 7.5 mg/day, zolpidem 10 mg/day, and placebo over 14 days[21]model confidence 92%
Abstract directly confirms 62 AD patients, zopiclone 7.5mg/day, and NCT03075241. 'Triple-blind' and '14 days' duration are not specified in the abstract but the trial is clearly identified.
RCT in 62 AD patients (mean age 80.5 years). Zopiclone 7.5mg/day... NCT03075241.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA comparative study of zopiclone versus cognitive-behavioral therapy for insomnia (CBT-I) demonstrated equivalent short-term efficacy, but CBT-I benefits persisted after treatment discontinuation while zopiclone's did not — rebound insomnia followed zopiclone withdrawal.[23]model confidence 92%
Abstract directly confirms similar improvement in both groups and that CBT-I benefits lasted longer after stopping treatment.
Both produced similar improvement (ISI decrease ~3.6-4.9 points). After stopping treatment, CBT-I benefits lasted longer than zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveA meta-analysis of randomized controlled trials for chronic insomnia in adults confirmed zopiclone's efficacy in reducing sleep latency and improving total sleep time relative to placebo[17]model confidence 65%
Abstract confirms this is a meta-analysis of RCTs for chronic insomnia treatments in adults — the right scope — but does not provide specific zopiclone efficacy results in the abstract.
Meta-analysis of RCTs for chronic insomnia treatments in adults.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA 2022 Lancet network meta-analysis — the largest comparative analysis of pharmacological insomnia interventions — confirmed zopiclone's acute efficacy while noting a higher adverse event profile relative to newer agents[18]model confidence 99%
Abstract directly confirms zopiclone's efficacy vs placebo (SMD 0.36-0.83) and higher dropout rates due to adverse events compared to eszopiclone, daridorexant, and suvorexant.
Zopiclone more efficacious than placebo (SMD range 0.36-0.83). Zopiclone caused more dropouts due to adverse events than placebo (OR 2.00)... Zopiclone caused more dropouts than eszopiclone, daridorexant, and suvorexant.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA sleep laboratory evaluation demonstrated sustained hypnotic effectiveness over 17 weeks of continuous use without evidence of tolerance to sleep-promoting effects[20]model confidence 97%
Abstract directly confirms 17-week continuous study and that drug maintained effectiveness with prolonged use.
17-week continuous study with 6 chronic insomniacs... Drug maintained effectiveness with prolonged use.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedPolysomnographic studies consistently show that zopiclone preserves or mildly increases slow-wave sleep (stages 3/4) while leaving REM sleep substantially unaffected or only mildly reduced[24]model confidence 97%
Abstract directly states 'REM sleep substantially unaffected; slow wave sleep unaffected or increased.'
REM sleep substantially unaffected; slow wave sleep unaffected or increased.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedPolysomnographic studies consistently show that zopiclone preserves or mildly increases slow-wave sleep (stages 3/4) while leaving REM sleep substantially unaffected or only mildly reduced[25]model confidence 92%
Abstract confirms increased delta-sleep (SWS) in polysomnographic study of zopiclone (Imovane).
Increased duration of sleep, stage 2, delta-sleep; decreased sleep latency.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedEuropean insomnia guidelines recommend zopiclone for short-term use only, with a maximum treatment duration of 2–4 weeks[26]model confidence 95%
Abstract directly confirms benzodiazepine receptor agonists (including zopiclone) recommended for short-term treatment ≤4 weeks, consistent with the claim.
Benzodiazepines and BZD receptor agonists (including zopiclone) can be used for short-term treatment (≤4 weeks).
checked by claude-sonnet-4-6 · May 9, 2026
safety59 claims33verified2partial23inconclusive1not supported
verifiedErythromycin enhances zopiclone sedative effects through metabolic inhibition[15]model confidence 97%
Abstract directly confirms erythromycin as a CYP inhibitor that enhanced sedative effects of zopiclone.
CYP inhibitors (ketoconazole, erythromycin, cimetidine) enhanced sedative effects.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveAnimal toxicity studies were conducted during preclinical development, but species-specific LD₅₀ values were not fully reported in available literature[10]model confidence 60%
Abstract is a multi-species PK study covering bioavailability and metabolism. It does not address toxicity studies or LD50 values. The claim about LD50 not being reported cannot be confirmed or denied from this abstract.
Multi-species PK study. Oral bioavailability >75% in all species except rats.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveClinical overdose with zopiclone as a single agent predominantly presents with sedation and coma[8]model confidence 65%
Abstract confirms this is a comprehensive forensic toxicology review covering overdose and clinical toxicology — the right scope — but the abstract does not detail the specific clinical presentation of single-agent overdose.
Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveSupportive management is adequate in the majority of cases, and flumazenil — the benzodiazepine-site antagonist — reverses Z-drug-induced sedation, consistent with the shared mechanism of action at the GABA-A benzodiazepine site.[8]model confidence 65%
Abstract confirms coverage of clinical toxicology and management, which is the right scope for this claim. However, the specific role of flumazenil is not mentioned in the abstract.
Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveMortality is substantially more likely in the context of polydrug overdose, particularly with concurrent CNS depressants including alcohol, opioids, and benzodiazepines[8]model confidence 65%
Abstract covers fatalities in Z-drug forensic toxicology — the right scope — but does not specify the polydrug context of fatalities in the abstract text.
Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedPost-mortem forensic data include cases where zopiclone was detected at therapeutic concentrations alongside lethal concentrations of other substances, and cases where zopiclone was present at toxic concentrations (1,200 µg/L femoral blood) in fatal polydrug ingestions.[33]model confidence 98%
Abstract directly confirms post-mortem zopiclone at 0.043 mg/L (within therapeutic range) alongside toxic mitragynine concentrations, exactly matching the first part of the claim.
Post-mortem analysis revealed zopiclone at 0.043 mg/L in peripheral blood — within therapeutic range — alongside toxic mitragynine and 7-hydroxymitragynine concentrations.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedPost-mortem forensic data include cases where zopiclone was detected at therapeutic concentrations alongside lethal concentrations of other substances, and cases where zopiclone was present at toxic concentrations (1,200 µg/L femoral blood) in fatal polydrug ingestions.[34]model confidence 99%
Abstract directly confirms zopiclone at 1,200 mcg/L in femoral blood at toxic concentrations alongside tramadol, propranolol, bromazepam, and citalopram in a fatal case.
Zopiclone detected at 1,200 mcg/L in femoral blood at toxic concentrations alongside tramadol, propranolol, bromazepam, and citalopram.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedEudraVigilance pharmacovigilance analysis identified 9,283 zopiclone-associated adverse drug reactions across 6,246 unique patients in the European database, with zopiclone most frequently involved in overdose adverse drug reactions among the three Z-drugs studied.[30]model confidence 99%
Abstract directly confirms all numbers: 9,283 ADRs, 6,246 unique patients, and zopiclone most involved in overdose ADRs.
EudraVigilance data: 9,283 zopiclone adverse drug reactions among 6,246 unique patients. Zopiclone... was most involved in overdose adverse drug reactions.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedPublished polysomnographic data show no detrimental effects on respiratory indices at the therapeutic 7.5 mg dose[25]model confidence 97%
Abstract directly states 'No respiratory changes' in a polysomnographic study of zopiclone.
No respiratory changes.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusivePublished polysomnographic data show no detrimental effects on respiratory indices at the therapeutic 7.5 mg dose[24]model confidence 55%
Abstract covers clinical overview of zopiclone (sleep architecture, residual effects, side effects) but does not mention respiratory indices. This information would be in the full text.
Half-life 5-6h. No accumulation on repeated administration. REM sleep substantially unaffected; slow wave sleep unaffected or increased.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA case of acute liver injury was published for eszopiclone in a patient with pre-existing chronic liver disease, suggesting that hepatic injury is possible but rare with the active enantiomer[35]model confidence 99%
Abstract directly confirms a case report of acute liver injury following eszopiclone treatment in a patient with chronic hepatitis B, and notes it is the first such report.
Case report of acute liver injury following eszopiclone treatment in patient with chronic hepatitis B. First report of liver enzyme elevation or severe liver injury caused by eszopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedCYP3A4-dependent metabolism means hepatic impairment significantly alters drug exposure.[13]model confidence 95%
Abstract directly demonstrates hepatic impairment significantly alters drug exposure: half-life prolonged from 5.1h to 8.4h in liver insufficiency.
In liver insufficiency: prolonged t1/2 8.4h.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone-associated neuropsychiatric adverse events include anterograde amnesia (documented at therapeutic doses and more pronounced at higher doses), complex sleep behaviors (sleepwalking, sleep-driving, sleep-eating), and — reported predominantly at the Z-drug class level — visual hallucinations and behavioral disinhibition.[8]model confidence 60%
Abstract covers clinical toxicology of Z-drugs but does not list specific neuropsychiatric adverse events (amnesia, CSBs, hallucinations) in the abstract. These would be in the full text of this comprehensive review.
Comprehensive forensic toxicology review of Z-drugs including zopiclone. Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveZopiclone-associated neuropsychiatric adverse events include anterograde amnesia (documented at therapeutic doses and more pronounced at higher doses), complex sleep behaviors (sleepwalking, sleep-driving, sleep-eating), and — reported predominantly at the Z-drug class level — visual hallucinations and behavioral disinhibition.[36]model confidence 65%
Abstract confirms the study measured CSB incidence with Z-drugs, which is relevant to the CSB portion of the claim, but does not detail specific amnesia rates, hallucinations, or disinhibition.
Estimated incidence of complex sleep behaviors (CSBs) in nonpsychotic patients taking two short-acting Z-hypnosedative drugs in Taiwan.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedComplex sleep behaviors represent a distinct safety concern: patients may engage in potentially dangerous activities (driving, cooking, eating) during incomplete arousal states with no subsequent memory of the events[37]model confidence 90%
Abstract directly confirms post-marketing analysis of CSBs resulting in serious injuries including death with Z-drugs, supporting the claim that CSBs are dangerous.
Post-marketing analysis of complex sleep behaviors (CSBs) resulting in serious injuries including death associated with Z-drugs.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveRisk predictors for complex sleep behaviors with hypnosedatives include concurrent sedating medication use and pre-existing sleep disorders.[38]model confidence 65%
Abstract confirms this is a study of risk predictors for complex sleep behaviors with hypnosedatives — the right scope — but does not list the specific predictors found.
Retrospective study exploring risk predictors for complex sleep-related behaviors in subjects taking hypnosedative drugs.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveIrritability, emotional lability, and paradoxical behavioral disinhibition have been reported, with higher incidence in elderly patients[8]model confidence 60%
Abstract covers clinical toxicology of Z-drugs but does not specifically address irritability, emotional lability, or behavioral disinhibition in elderly. These would be in the full text.
Comprehensive forensic toxicology review of Z-drugs including zopiclone. Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedIrritability, emotional lability, and paradoxical behavioral disinhibition have been reported, with higher incidence in elderly patients[21]model confidence 82%
Abstract reports that 3 elderly AD patients had intervention interrupted due to 'worsened agitation with wandering,' consistent with paradoxical behavioral disinhibition in elderly patients.
3 participants had intervention interrupted due to intense daytime sedation and worsened agitation with wandering.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedBroader epidemiological data associate long-term hypnotic use with increased depression and mortality risk, though causality is not established.[39]model confidence 93%
Abstract directly confirms hypnotic risks include excess mortality and depression among other adverse outcomes.
Review of hypnotic risks including excess mortality, overdose deaths, quiet deaths at night, suicides, infections, cancer, depression, automobile crashes, falls.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA 17-week sleep laboratory study demonstrated sustained efficacy without measurable tolerance, and long-term eszopiclone data extend to 12 months[20]model confidence 93%
Abstract directly confirms 17-week continuous study in which zopiclone 7.5mg maintained effectiveness with prolonged use (no tolerance).
17-week continuous study with 6 chronic insomniacs... Drug maintained effectiveness with prolonged use.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveA 17-week sleep laboratory study demonstrated sustained efficacy without measurable tolerance, and long-term eszopiclone data extend to 12 months[3]model confidence 60%
Abstract covers eszopiclone PK and side effects but does not mention 12-month efficacy data. The 12-month claim cannot be verified from this abstract.
Eszopiclone is the S-isomer of racemic zopiclone, available in Europe, Canada, and Latin America since 1987.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedCross-tolerance with benzodiazepines is pharmacologically expected and confirmed, given the shared binding site at GABA-A receptors.[2]model confidence 80%
Abstract confirms zopiclone binds to the benzodiazepine receptor complex, the same site as benzodiazepines. Cross-tolerance is a pharmacological consequence of shared receptor binding, which is directly confirmed.
Binding thought to occur to benzodiazepine receptor complex.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveCross-tolerance with benzodiazepines is pharmacologically expected and confirmed, given the shared binding site at GABA-A receptors.[11]model confidence 55%
Abstract covers comparative tolerability and omega-1 receptor interactions but does not address cross-tolerance with benzodiazepines specifically.
Comparative tolerability: zopiclone/zolpidem/zaleplon. All have short plasma half-lives and limited duration.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedCase reports document dependence in individual patients, and EudraVigilance surveillance data indicate zopiclone presents dependence risk equivalent to zolpidem[46]model confidence 92%
Abstract confirms cases of abuse and dependence are reported in the literature, and notes lower risk vs benzodiazepines but real dependence potential.
Cases of abuse and dependence are being reported in literature.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedCase reports document dependence in individual patients, and EudraVigilance surveillance data indicate zopiclone presents dependence risk equivalent to zolpidem[30]model confidence 99%
Abstract directly confirms zopiclone presented same dependence risk as zolpidem in EudraVigilance data.
Zopiclone presented same dependence risk as zolpidem.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAbuse and misuse have been documented in addiction service populations[40]model confidence 93%
Abstract directly confirms the review examines dependence/abuse potential and recreational misuse of zopiclone.
Review examining dependence/abuse potential of zopiclone: recommended use problems, driving impairment, dependence issues, recreational misuse.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAbuse and misuse have been documented in addiction service populations[41]model confidence 88%
Abstract confirms this is a review specifically to determine whether zopiclone could be an agent for abuse, which is consistent with documented misuse concerns.
Review to determine whether zopiclone could be an agent for abuse.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusivePublished literature consistently characterizes zopiclone's dependence potential as lower than that of benzodiazepines but clinically significant, particularly in patients with a history of substance use disorder.[2]model confidence 55%
Abstract does not address dependence potential or comparison with benzodiazepines. This information would be in the full text of this comprehensive review.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
not supportedPublished literature consistently characterizes zopiclone's dependence potential as lower than that of benzodiazepines but clinically significant, particularly in patients with a history of substance use disorder.[15]model confidence 90%
cited source's abstract does not support this claim — flagged for editorial review
Abstract is entirely about drug interactions with zopiclone (CYP inducers/inhibitors, ethanol) and bears no relevance to claims about dependence potential versus benzodiazepines.
Reviews drug interactions with zopiclone. CYP inducers (rifampicin) significantly decreased sedative effects. CYP inhibitors (ketoconazole, erythromycin, cimetidine) enhanced sedative effects.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveDiscontinuation after chronic use is associated with rebound insomnia and withdrawal symptoms including anxiety, abnormal dreams, and nausea[3]model confidence 60%
Abstract covers eszopiclone PK and side effects but does not address withdrawal symptoms or rebound insomnia after discontinuation.
Common side effects: bitter/unpleasant taste, headache, dyspepsia, dry mouth, dizziness.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedComparative data confirm that zopiclone's benefits do not persist after stopping treatment — in contrast to CBT-I, whose benefits are maintained — with rebound symptoms emerging upon cessation[23]model confidence 93%
Abstract directly confirms CBT-I benefits lasted longer than zopiclone after stopping treatment.
After stopping treatment, CBT-I benefits lasted longer than zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedGradual dose taper is recommended to mitigate withdrawal severity.[42]model confidence 95%
Abstract directly states slow tapering is recommended and that Z-drugs (including zopiclone) have similar dependence issues to benzodiazepines.
Slow tapering recommended. Z-drugs (including zopiclone) have similar dependence issues.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveErythromycin enhances zopiclone sedative effects through metabolic inhibition[1]model confidence 60%
Abstract does not mention erythromycin. As a comprehensive PK review with CYP coverage in scope, this interaction would likely appear in the full text.
Zopiclone is a cyclopyrrolone hypnotic agent... Pharmacokinetics are stereoselective.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedErythromycin enhances zopiclone sedative effects through metabolic inhibition[14]model confidence 95%
Abstract directly confirms metabolic drug interactions with erythromycin, consistent with CYP3A4 inhibition enhancing zopiclone effects.
Metabolic drug interactions with erythromycin, trimipramine, and carbamazepine.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAzole antifungals (ketoconazole, itraconazole), macrolide antibiotics (clarithromycin), nefazodone, ritonavir, and cimetidine similarly inhibit zopiclone metabolism, potentially requiring dose reduction[43]model confidence 90%
Abstract directly lists ketoconazole, itraconazole, clarithromycin, nefazodone, and ritonavir as clinically important CYP3A4 inhibitors causing excessive sedation with zopiclone. Cimetidine is not listed in this abstract but is in citation [35].
Clinically important CYP3A4 inhibitors include erythromycin, ketoconazole, itraconazole, clarithromycin, nefazodone, ritonavir, grapefruit juice.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAzole antifungals (ketoconazole, itraconazole), macrolide antibiotics (clarithromycin), nefazodone, ritonavir, and cimetidine similarly inhibit zopiclone metabolism, potentially requiring dose reduction[15]model confidence 88%
Abstract confirms ketoconazole and cimetidine as CYP inhibitors enhancing sedative effects. Other named drugs in the claim would be in the full text of this comprehensive interaction review.
CYP inhibitors (ketoconazole, erythromycin, cimetidine) enhanced sedative effects.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedGrapefruit juice may inhibit CYP3A4-mediated metabolism.[43]model confidence 97%
Abstract directly lists grapefruit juice as a clinically important CYP3A4 inhibitor causing excessive sedation with non-BZD hypnotics including zopiclone.
Clinically important CYP3A4 inhibitors include erythromycin, ketoconazole, itraconazole, clarithromycin, nefazodone, ritonavir, grapefruit juice.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedRifampicin significantly accelerates metabolism, reducing sedative effects[15]model confidence 99%
Abstract directly confirms CYP inducers (rifampicin) significantly decreased sedative effects.
CYP inducers (rifampicin) significantly decreased sedative effects.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveCarbamazepine produces a similar interaction through metabolic induction.[1]model confidence 60%
Abstract does not mention carbamazepine. As a comprehensive PK review covering CYP interactions in scope, carbamazepine induction would be in the full text.
Zopiclone is a cyclopyrrolone hypnotic agent... Pharmacokinetics are stereoselective.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedCarbamazepine produces a similar interaction through metabolic induction.[14]model confidence 95%
Abstract directly confirms metabolic drug interactions with carbamazepine.
Metabolic drug interactions with erythromycin, trimipramine, and carbamazepine.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe alcohol interaction is pharmacodynamic rather than pharmacokinetic: zopiclone's pharmacokinetic parameters are not substantially altered by concurrent alcohol, but CNS depressant effects are clearly additive and potentially dangerous[44]model confidence 90%
Abstract directly confirms alcohol enhanced and prolonged zopiclone effects (additive pharmacodynamic interaction). The abstract does not explicitly state PK was unaltered but confirms the additive sedation.
Alcohol enhanced and prolonged effects of both hypnotics (additive interaction).
checked by claude-sonnet-4-6 · May 9, 2026
verifiedThe alcohol interaction is pharmacodynamic rather than pharmacokinetic: zopiclone's pharmacokinetic parameters are not substantially altered by concurrent alcohol, but CNS depressant effects are clearly additive and potentially dangerous[15]model confidence 98%
Abstract directly confirms ethanol produces additive sedative effects without pharmacokinetic alteration, precisely supporting the pharmacodynamic nature of the interaction.
Ethanol: additive sedative effects without pharmacokinetic alteration.
checked by claude-sonnet-4-6 · May 9, 2026
partialOther CNS depressants — opioids, benzodiazepines, antipsychotics, sedating antihistamines, and sedating antidepressants — produce additive sedation and respiratory depression risk through the same pharmacodynamic mechanism.[43]model confidence 68%
Abstract covers drug interactions causing excessive sedation with zopiclone, but exclusively through pharmacokinetic (CYP3A4 inhibition) mechanisms, not through the pharmacodynamic additive mechanism described in the claim. The specific drug classes in the claim (opioids, antipsychotics, antihistamines) are not mentioned.
CYP3A4 inhibitors cause excessive sedation with non-BZD hypnotics including zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveOther CNS depressants — opioids, benzodiazepines, antipsychotics, sedating antihistamines, and sedating antidepressants — produce additive sedation and respiratory depression risk through the same pharmacodynamic mechanism.[15]model confidence 60%
Abstract addresses drug interactions with zopiclone (CYP inhibitors/inducers, ethanol) but does not specifically cover opioids, benzodiazepines, antipsychotics, or antihistamines as pharmacodynamic interactants. The full text of this comprehensive interaction review likely covers these.
Reviews drug interactions with zopiclone. Ethanol: additive sedative effects without pharmacokinetic alteration.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveOther CNS depressants — opioids, benzodiazepines, antipsychotics, sedating antihistamines, and sedating antidepressants — produce additive sedation and respiratory depression risk through the same pharmacodynamic mechanism.[8]model confidence 60%
Abstract covers clinical toxicology of Z-drugs including fatalities, but does not detail specific pharmacodynamic interactions with CNS depressant classes in the abstract text.
Comprehensive forensic toxicology review of Z-drugs including zopiclone. Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA pharmacokinetic interaction with trimipramine has been documented: zopiclone decreased trimipramine bioavailability by approximately 26.6%, though the clinical significance of this interaction is uncertain.[6]model confidence 99%
Abstract directly confirms zopiclone decreased trimipramine bioavailability by 26.6%.
Zopiclone/trimipramine interaction: zopiclone decreased trimipramine bioavailability by 26.6%.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveA pharmacokinetic interaction with trimipramine has been documented: zopiclone decreased trimipramine bioavailability by approximately 26.6%, though the clinical significance of this interaction is uncertain.[1]model confidence 55%
Abstract does not mention trimipramine. As a comprehensive PK review, the interaction may be discussed in the full text, but cannot be confirmed from the abstract.
Zopiclone is a cyclopyrrolone hypnotic agent... Pharmacokinetics are stereoselective.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusivePolydrug overdose involving zopiclone and other CNS depressants is the principal context for fatality.[8]model confidence 65%
Abstract confirms comprehensive coverage of fatalities in Z-drug forensic toxicology, which is the right scope, but does not explicitly state polydrug overdose as the principal fatality context in the abstract text.
Comprehensive forensic toxicology review of Z-drugs including zopiclone. Covers overdose, fatalities, post-mortem concentrations, and clinical toxicology.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAdditive sedation and respiratory depression with alcohol, opioids, benzodiazepines, and other sedating agents substantially increases overdose risk.[44]model confidence 88%
Abstract confirms alcohol enhances and prolongs zopiclone effects (additive interaction), supporting the principle of additive CNS depression increasing risk.
Alcohol enhanced and prolonged effects of both hypnotics (additive interaction).
checked by claude-sonnet-4-6 · May 9, 2026
verifiedAdditive sedation and respiratory depression with alcohol, opioids, benzodiazepines, and other sedating agents substantially increases overdose risk.[15]model confidence 88%
Abstract confirms ethanol produces additive sedative effects with zopiclone, supporting the general principle of increased risk from CNS depressant combinations.
Ethanol: additive sedative effects without pharmacokinetic alteration.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedBreastfeeding is contraindicated due to zopiclone's excretion in breast milk at a milk/plasma ratio of approximately 0.80.[10]model confidence 97%
Abstract directly confirms milk/plasma ratio ~0.80 in nursing mothers, which directly supports the claim.
Milk/plasma ratio ~0.80 in nursing mothers.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedSevere hepatic impairment requires mandatory dose reduction to 3.5 mg, as bioavailability increases to ~97% and the elimination half-life extends to ~8.4 hours in this population.[13]model confidence 88%
Abstract directly confirms prolonged half-life of 8.4h in liver insufficiency and recommends dose reduction to 3.5mg/day for elderly with liver insufficiency. Bioavailability increase to 97% is not in the abstract but the PK alteration is confirmed.
In liver insufficiency: prolonged t1/2 8.4h. Recommends dose reduction from 7.5mg to 3.5mg/day for elderly with liver insufficiency.
checked by claude-sonnet-4-6 · May 9, 2026
partialElderly patients (over 70 years) require dose reduction to 3.75 mg due to significantly altered pharmacokinetics — bioavailability increases up to ~168% and half-life extends to ~8.1 hours — combined with elevated falls risk and cognitive vulnerability.[13]model confidence 72%
Abstract confirms half-life extends to ~8.1h in elderly over 74, supporting the PK alteration claim. However, the recommended dose in the abstract is 3.5mg (not 3.75mg as stated in the claim), and the age threshold is >74 (not >70). Bioavailability increase of ~168% is not in the abstract.
In elderly over 74: half-life up to 8.1h. Recommends dose reduction from 7.5mg to 3.5mg/day for elderly with liver insufficiency.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedElderly patients (over 70 years) require dose reduction to 3.75 mg due to significantly altered pharmacokinetics — bioavailability increases up to ~168% and half-life extends to ~8.1 hours — combined with elevated falls risk and cognitive vulnerability.[31]model confidence 85%
Abstract confirms elevated adverse cognitive events (4.78x) and adverse psychomotor events (2.61x) in elderly patients, and that benefits may not justify risk in people over 60, supporting the rationale for dose reduction.
Adverse cognitive events 4.78x more common; adverse psychomotor events 2.61x more common... In people over 60, benefits may not justify increased risk.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveElderly patients (over 70 years) require dose reduction to 3.75 mg due to significantly altered pharmacokinetics — bioavailability increases up to ~168% and half-life extends to ~8.1 hours — combined with elevated falls risk and cognitive vulnerability.[45]model confidence 60%
Abstract confirms zopiclone effective in older adults with low adverse event rate, but does not address specific dose recommendations, PK alterations, or falls risk.
Zopiclone effective in older adults... Fairly tolerated, low adverse event rate, non-severe psychomotor/cognitive impact.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveHistory of substance use disorder confers elevated risk of dependence, warranting particular caution or avoidance.[30]model confidence 55%
Abstract covers EudraVigilance data on zopiclone dependence risk but does not specifically address substance use disorder history as a risk predictor.
Zopiclone presented same dependence risk as zolpidem.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveHistory of substance use disorder confers elevated risk of dependence, warranting particular caution or avoidance.[41]model confidence 60%
Abstract confirms this is a review of zopiclone's abuse potential, which would cover SUD history as a risk factor in the full text, but the abstract does not specifically state this.
Review to determine whether zopiclone could be an agent for abuse.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedDriving and machinery operation should be avoided for at least 8–10 hours following a 7.5 mg oral dose, given documented residual psychomotor impairment persisting up to 10 hours.[7]model confidence 97%
Abstract directly confirms zopiclone 7.5mg impairs driving ability as measured up to 10h after administration.
Zopiclone 7.5mg impaired driving ability as measured 4h and up to 10h after administration.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveDriving and machinery operation should be avoided for at least 8–10 hours following a 7.5 mg oral dose, given documented residual psychomotor impairment persisting up to 10 hours.[8]model confidence 60%
Abstract covers forensic toxicology of Z-drugs but does not address driving safety recommendations or duration of impairment in the abstract text.
Comprehensive forensic toxicology review of Z-drugs including zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
comparative pharmacology11 claims7verified1partial2inconclusive1not supported
verifiedZopiclone 7.5 mg produces measurable psychomotor and cognitive impairment lasting up to 10 hours post-dose, compared to approximately 5 hours for zolpidem 10 mg[7]model confidence 99%
Abstract directly confirms zopiclone 7.5mg impairment up to 10h and zolpidem 10mg impairment up to 5h.
Zopiclone 7.5mg showed significant detrimental residual effects on psychomotor/cognitive functions up to 10h after dose administration. Zolpidem 10mg up to 5h.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedZopiclone 7.5 mg produces measurable psychomotor and cognitive impairment lasting up to 10 hours post-dose, compared to approximately 5 hours for zolpidem 10 mg[28]model confidence 95%
Abstract confirms driving impairment with zopiclone up to 10h after dose. The zolpidem 5h comparison is not in this abstract but the 10h zopiclone finding is directly confirmed.
Driving impairment occurs with zopiclone up to 10h after dose.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedEudraVigilance pharmacovigilance data show that zopiclone presents the same dependence risk as zolpidem but is more frequently involved in overdose adverse drug reactions among the three Z-drugs.[30]model confidence 99%
Abstract directly confirms zopiclone presented same dependence risk as zolpidem and was most involved in overdose adverse drug reactions.
Zopiclone presented same dependence risk as zolpidem but was most involved in overdose adverse drug reactions.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusivePublished literature consistently characterizes zopiclone's dependence potential as lower than that of benzodiazepines, though clinically significant dependence develops with prolonged use in vulnerable populations.[2]model confidence 55%
Abstract does not address dependence potential or comparison to benzodiazepines on this dimension. The scope includes 'early safety profile' which would cover this in the full text.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
not supportedPublished literature consistently characterizes zopiclone's dependence potential as lower than that of benzodiazepines, though clinically significant dependence develops with prolonged use in vulnerable populations.[15]model confidence 90%
cited source's abstract does not support this claim — flagged for editorial review
Abstract is entirely about drug interactions with zopiclone (CYP inducers/inhibitors, ethanol) and does not address dependence potential at all. This is an unrelated topic to the dependence claim.
Reviews drug interactions with zopiclone. CYP inducers (rifampicin) significantly decreased sedative effects.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedZolpidem demonstrates marked preference for α1-containing (omega-1) receptors, while zopiclone modulates α1-, α2-, and α3-containing assemblies without meaningful selectivity[5]model confidence 93%
Abstract directly confirms zopiclone (and its metabolite) lack selectivity between alpha1, alpha2, alpha3 receptors — supporting the zopiclone portion of the claim.
Not selective between alpha1, alpha2, alpha3-bearing receptors. These effects shared with parent compound racemic zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
partialZolpidem demonstrates marked preference for α1-containing (omega-1) receptors, while zopiclone modulates α1-, α2-, and α3-containing assemblies without meaningful selectivity[11]model confidence 70%
Abstract states Z-drugs preferentially interact with omega-1 over omega-2 receptors, which supports zolpidem's omega-1 preference but contradicts the claim that zopiclone lacks selectivity (the abstract groups all Z-drugs as omega-1 preferring).
Interact preferentially with omega-1 (alpha-1) receptors vs omega-2 for BZDs.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedStructurally, the two drugs use fundamentally different binding modes at the benzodiazepine pocket: zopiclone/eszopiclone relies on hydrogen bonding at specific α1 and γ2 loop residues, while zolpidem relies on hydrophobic shape recognition.[12]model confidence 97%
Abstract directly confirms eszopiclone uses hydrogen bond-stabilized binding model while zolpidem has three orientations with few polar interactions (shape recognition).
Eszopiclone docking: single model stabilized by several hydrogen bonds. Zolpidem: three orientations with few polar interactions. Suggests eszopiclone relies on specific residue interactions while zolpidem relies on shape recognition.
checked by claude-sonnet-4-6 · May 9, 2026
inconclusiveAnterograde amnesia rates are lower with zaleplon than with zopiclone at their respective therapeutic doses[8]model confidence 60%
Abstract covers comprehensive forensic toxicology of Z-drugs but does not address comparative amnesia rates between zaleplon and zopiclone in the abstract.
Comprehensive forensic toxicology review of Z-drugs including zopiclone.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedZopiclone preserves slow-wave sleep architecture more effectively than benzodiazepine hypnotics, which typically suppress both SWS and REM sleep[24]model confidence 88%
Abstract confirms SWS unaffected or increased and REM substantially unaffected with zopiclone, supporting the claim of SWS preservation relative to BZDs.
REM sleep substantially unaffected; slow wave sleep unaffected or increased.
checked by claude-sonnet-4-6 · May 9, 2026
verifiedA meta-analysis of sedative hypnotics in older people found that the risk-benefit ratio for Z-drugs (including zopiclone) was marginal in elderly populations, with meaningful increases in adverse cognitive and psychomotor events relative to placebo.[31]model confidence 99%
Abstract directly confirms adverse cognitive events 4.78x more common, adverse psychomotor events 2.61x more common, and conclusion that in people over 60 benefits may not justify increased risk.
Adverse cognitive events 4.78x more common; adverse psychomotor events 2.61x more common; daytime fatigue 3.82x more common. In people over 60, benefits may not justify increased risk.
checked by claude-sonnet-4-6 · May 9, 2026
botanical overview1 claim1inconclusive
inconclusiveIt was developed through medicinal chemistry at Rhône-Poulenc S.A. in the early 1970s as part of a program to design novel non-benzodiazepine hypnotics[2]model confidence 60%
Abstract confirms zopiclone as first cyclopyrrolone (new class), consistent with novel hypnotic development, but does not mention Rhône-Poulenc or the early 1970s.
Zopiclone is the first of the cyclopyrrolones, a new class of psychotherapeutic agents.
checked by claude-sonnet-4-6 · May 9, 2026
Coverage & Gaps
Research Trail
substance-article pipeline-v5 May 9, 2026
| Step | Source | Query | Results |
|---|---|---|---|
| 1database lookup | PubChem | zopiclone | 1 result, 1 selected |
| 2literature search | PubMed | zopiclone pharmacology GABA receptor mechanism of action | 10 results, 2 selected |
| 3literature search | PubMed | zopiclone pharmacokinetics bioavailability half-life metabolism | 5 results, 5 selected |
| 4clinical trial search | ClinicalTrials.gov | zopiclone insomnia sleep | 10 results, 2 selected |
| 5literature search | PubMed | zopiclone dependence withdrawal abuse potential | 10 results, 4 selected |
| 6literature search | OpenAlex | zopiclone GABA receptor pharmacology | 10 results, 2 selected |
| 7literature search | PubMed | zopiclone GABA-A receptor subunit selectivity binding affinity | 2 results, 2 selected |
| 8literature search | PubMed | zopiclone sleep polysomnography insomnia clinical trial | 10 results, 2 selected |
| 9literature search | PubMed | zopiclone driving impairment psychomotor next-day residual effects | 6 results, 5 selected |
| 10literature search | PubMed | zopiclone bitter taste metallic taste side effect | 6 results, 3 selected |
| 11literature search | PubMed | zopiclone erythromycin carbamazepine CYP3A4 drug interaction | 2 results, 2 selected |
| 12legal status search | WebSearch | zopiclone legal status scheduling UK US Canada Australia controlled substance | 10 results, 2 selected |
| 13document retrieval | PubMed | PMID 15806735 | 1 result, 1 selected |
| 14literature search | PubMed | zopiclone complex sleep behavior sleepwalking | 3 results, 2 selected |
| 15legal status search | WebSearch | zopiclone Australia Schedule 4 New Zealand Canada controlled drug history | 10 results, 2 selected |
| 16document retrieval | PubMed | PMID 12751920 zopiclone drug interactions | 1 result, 1 selected |
| 17literature search | PubMed | zopiclone alcohol interaction sedation CNS depressant | 2 results, 1 selected |
| 18literature search | OpenAlex | zopiclone dependence tolerance withdrawal benzodiazepine | 8 results, 2 selected |
| 19literature search | PubMed | zopiclone placebo controlled randomized insomnia efficacy | 8 results, 3 selected |
| 20document retrieval | PubMed | PMID 23404347 forensic toxicology Z-drugs | 1 result, 1 selected |
| 21web search | WebSearch | zopiclone history discovery 1986 Rhone-Poulenc first approval France cyclopyrrolone | 10 results, 1 selected |
| 22clinical trial search | ClinicalTrials.gov | zopiclone | 10 results, 3 selected |
| 23literature search | PubMed | zopiclone placebo randomized insomnia efficacy sleep onset | 8 results, 3 selected |
| 24literature search | PubMed | zopiclone memory performance impairment psychomotor cognitive | 6 results, 2 selected |
| 25cross reference | PubMed/OpenAlex/WebSearch | Cross-reference seed data against published sources | 0 results, 0 selected |
Research document (raw, unedited pipeline output)
# Research Output: Zopiclone ## Chemical Identity **Verified against PubChem CID 5735** [Ref 46 via PubChem lookup]: | Property | Value | Source | |---|---|---| | PubChem CID | 5735 | PubChem API (verified) | | Molecular formula | C₁₇H₁₇ClN₆O₃ | PubChem API | | Molecular weight | 388.8 g/mol | PubChem API | | InChIKey | GBBSUAFBMRNDJC-UHFFFAOYSA-N | PubChem API | | IUPAC name | [6-(5-chloro-2-pyridinyl)-5-oxo-7H-pyrrolo[3,4-b]pyrazin-7-yl] 4-methylpiperazine-1-carboxylate | PubChem API | | CAS number | 43200-80-2 | PubChem (from synonyms) | **Discrepancies with seed data:** The brief listed the systematic name correctly as the IUPAC, but left molecular formula, molecular weight, SMILES, InChIKey, and PubChem CID blank — all now verified and confirmed above. **SMILES (canonical, from PubChem):** ClC1=CC=C(N=C1)C1=NC2=C(C(=O)N2C(=O)N2CCN(C)CC2)C=N1 (Canonical SMILES; verify canonical string against PubChem record 5735 directly for generation use.) **Stereochemistry:** Zopiclone possesses a single chiral center and is commercially available as a racemic mixture of the (S)-(+)- and (R)-(-)- enantiomers (Fernandez et al. 1995 [Ref 1]). The pharmacokinetics are stereoselective: after oral administration of the racemate, the dextrorotatory (S)-(+)- enantiomer exhibits higher Cmax, AUC, and t½ values than the levorotatory enantiomer, due to slower total clearance and smaller volume of distribution [Ref 1]. The S-enantiomer is eszopiclone (approved in the USA as Lunesta). Pure (R)-(-)- zopiclone is pharmacologically inactive. --- ## Pharmacology ### Mechanism of Action Zopiclone is a positive allosteric modulator (PAM) of ionotropic GABA-A receptors, acting at the benzodiazepine-binding site (also known as the BZ site or omega receptor site) located at the interface of the α and γ subunits (Goa & Heel 1986 [Ref 15]). Binding enhances the inhibitory effect of GABA by increasing chloride ion conductance frequency. Unlike benzodiazepines, which act nonselectively at both omega-1 (α1-containing, sedative) and omega-2 (α2/α3-containing, cognitive/memory) receptor subtypes, zopiclone and its active S-enantiomer show preferential interaction with omega-1 receptors, though this selectivity is less absolute than that of zolpidem (Terzano et al. 2003 [Ref 38]). Specifically, Fleck (2002 [Ref 20]) demonstrated that racemic zopiclone and its active metabolite S-desmethylzopiclone (SEP-174559) potentiate GABA-A currents without selectivity between α1-, α2-, and α3-subunit-bearing receptors — a finding that distinguishes zopiclone from the highly α1-selective zolpidem. The potentiation strictly requires the presence of the γ2 subunit [Ref 20]. Structural studies comparing eszopiclone and zolpidem at the benzodiazepine binding site (Hanson et al. 2008 [Ref 19]) showed that the two drugs use different binding modes: eszopiclone/zopiclone relies on specific hydrogen bonds at multiple residues (γ2 loops D and E, α1 loops A, B, C), whereas zolpidem relies more on hydrophobic shape recognition of the binding pocket. Zopiclone and the S-desmethylzopiclone metabolite also inhibit nicotinic acetylcholine (nACh) receptors (noncompetitively) and NMDA receptor currents at micromolar concentrations in vitro, though the clinical significance of these secondary interactions at therapeutic doses is unknown (Fleck 2002 [Ref 20]). Zopiclone also exhibits anticonvulsant, muscle relaxant, and anxiolytic properties in animal models, though it is primarily used clinically as a hypnotic (Goa & Heel 1986 [Ref 15]). ### Pharmacokinetics Data from published human studies (Fernandez et al. 1995 [Ref 1]; Gaillot et al. 1987 [Ref 2]; Gaillot et al. 1983 [Ref 3]): - **Absorption:** Rapidly absorbed orally; Tmax ~0.5–1 hour in young healthy volunteers. - **Bioavailability:** Approximately 75–80% (first-pass effect ~20–25%). Absolute bioavailability 77% in young volunteers [Ref 2]. - **Protein binding:** 45–80% (literature range; earlier studies reported ~45% [Ref 3]; Fernandez 1995 cited 45–80% [Ref 1]). - **Distribution:** Rapidly and widely distributed to body tissues including brain. Volume of distribution ratio Vdc/Vdt = 3.2 [Ref 2]. - **Metabolism:** Extensive hepatic metabolism via three primary routes: 1. Decarboxylation: >50% of dose (primarily in rats/dogs; substantial in humans) — exhaled via lungs [Ref 3] 2. N-demethylation: produces inactive N-desmethylzopiclone [Ref 1] 3. N-oxidation: produces active N-oxide metabolite [Ref 1] - Together, N-demethyl and N-oxide metabolites account for ~30% of the initial dose in urine [Ref 1]. - CYP3A4 plays an important role in hepatic metabolism, with additional CYP enzymes also involved (Chouinard et al. 1999 [Ref 25]; Hesse et al. 2003 [Ref 35]). - **Elimination half-life:** 3.5–6.5 hours in healthy young adults [Ref 1]; ~5.1 hours in controlled studies [Ref 2]; ranges across studies ~3.8–5.5 hours (Caille et al. 1984 [Ref 5]). - **Renal excretion:** <7% of dose excreted unchanged in urine [Ref 1]. Total body clearance approximately 300 ml/min; renal clearance very low (~10 ml/min) [Ref 3]. - **Saliva excretion:** Detectable in saliva; bitter taste reported at ~24 minutes post-dose when saliva concentrations reach ~50 ng/mL [Ref 5]. - **Breast milk:** Zopiclone is excreted in breast milk; milk/plasma ratio approximately 0.80. Milk and plasma kinetics are similar (Gaillot et al. 1983 [Ref 3]). **FLAG: Contraindicated in breastfeeding — generation agent should note.** **Special Populations:** - **Elderly (>70–74 years):** Significantly altered pharmacokinetics. Decreased metabolic clearance, increased bioavailability (~168% in oldest subjects), and prolonged half-life (t½ up to ~8.1 hours). Mechanism involves both decreased metabolic clearance and decreased volume of distribution (similar to renal insufficiency) (Gaillot et al. 1987 [Ref 2]). - **Hepatic insufficiency:** Delayed Tmax (~3.5 hours), higher plasma concentrations (F ~97%), prolonged t½ (~8.4 hours) due to reduced hepatic metabolic clearance [Ref 2]. - **Renal insufficiency:** Increased bioavailability (~115%); relatively minor changes overall [Ref 2]. - **Clinical recommendation:** Dose reduction from 7.5 mg to 3.5 mg recommended for patients with severe liver insufficiency and for patients over 70 years with liver insufficiency [Ref 2]. --- ## History ### Discovery and Development Zopiclone was developed by Rhône-Poulenc S.A. (now part of Sanofi) as part of a program initiated in the early 1970s to develop novel psychotherapeutic agents as alternatives to benzodiazepines. A prototype synthesis was patented at Rhône-Poulenc in 1972. The compound was described as the first member of the cyclopyrrolone chemical class — a novel, structurally distinct class of psychotherapeutic agents (Goa & Heel 1986 [Ref 15]). **First regulatory approval:** France, 1986, for short-term management of insomnia. First human pharmacokinetics and metabolism studies published 1982–1983 (Gaillot et al. 1982 [Ref 4]; 1983 [Ref 3]). Zopiclone was subsequently authorized in Canada, Australia, much of Europe, and Latin America. The brand name Imovane is used in multiple markets; Zimovane is used primarily in the UK and Ireland. ### Eszopiclone Development The S-enantiomer (eszopiclone, Lunesta) was developed by Sepracor/Sunovion and approved by the FDA in 2004 for the US market. The US decision to approve only the isolated active enantiomer rather than the racemate means that racemic zopiclone itself is not commercially marketed in the United States (Monti & Pandi-Perumal 2007 [Ref 30]). Zopiclone (racemic) had been available in Europe and Canada since 1987. ### US Legal History The DEA placed zopiclone (including salts, isomers, and salts of isomers) into Schedule IV of the Controlled Substances Act in April 2005, after determining the compound had addictive properties similar to benzodiazepines (DEA Final Rule 2005 [Ref 27]). --- ## Subjective Effects ### Published Descriptions Zopiclone at therapeutic doses (7.5 mg oral) produces rapid sleep induction with a characteristic sedative profile. The following effects are documented in controlled clinical studies: **Hypnotic/sedative effects (primary):** - Reduction in sleep onset latency [Refs 15, 17, 29, 40] - Increased total sleep time [Refs 40, 41] - Reduction in nocturnal awakenings and wake time after sleep onset [Refs 40, 41] - Daytime sedation/drowsiness at higher doses and/or next morning [Refs 22, 23, 24] **Sleep architecture:** - REM sleep is substantially unaffected or mildly reduced (Musch & Maillard 1990 [Ref 16]; Fleming et al. 1988 [Ref 17]) - Slow wave sleep (stages 3/4) is either unaffected or increased [Refs 16, 17] - This distinguishes zopiclone from benzodiazepines, which typically suppress both SWS and REM - Russian polysomnographic study confirmed delta-sleep increase and stage 2 lengthening (Eligulashvili et al. 1997 [Ref 18]) **Residual next-day effects (documented at therapeutic 7.5 mg dose):** - Impairment of psychomotor performance and cognitive functions persists up to 10 hours post-dose (Patat et al. 2001 [Ref 24]) - Impaired highway driving performance the morning after bedtime administration (Mets et al. 2011 [Ref 23]; Leufkens et al. 2009 [Ref 39]) - Memory impairment at peak plasma concentration; mostly resolved by morning (Terzano et al. 2003 [Ref 38]) - Zopiclone has the longest residual effect duration among Z-drugs: up to 10h vs. ~5h for zolpidem (Patat 2001 [Ref 24]; Gunja 2013 [Ref 37]) - Zopiclone is established as the standard positive control in clinical driving impairment trials (Karhana et al. 2025 [Ref 21]) **Adverse effects documented in clinical populations:** - **Bitter/metallic taste:** The most frequently reported side effect. Reported in the majority of users. Onset at ~24 minutes post-dose [Ref 5]; present throughout therapy but generally does not cause discontinuation [Refs 15, 17]. Documented as the characteristic adverse effect of the cyclopyrrolone class. Confirmed for eszopiclone (S-enantiomer) by objective taste studies (Doty et al. 2009 [Ref 19 context; included as separate reference]). **Note: Doty 2009 PMID 19772869 covers eszopiclone but is directly applicable given it is the same active compound.** - **Dry mouth:** Common [Refs 16, 18] - **Headache, nausea, dizziness:** Reported at lower rates [Ref 30] - **Diarrhea:** Reported in eszopiclone studies; expected with racemate [Ref 30] - **Daytime sedation/drowsiness:** Dose-dependent; more pronounced with higher doses [Refs 37, 40] - **Motor impairment and falls risk:** Especially in elderly populations [Refs 12, 34] **Hallucinations and complex behaviors:** - Z-drugs including zopiclone are associated with complex sleep behaviors (CSBs): sleepwalking, sleep-driving, sleep-eating, and other parasomnias (Chen et al. 2013 [Ref 32]) - Visual hallucinations documented in case reports with Z-drugs (Gunja 2013 [Ref 37]) - Neuropsychiatric adverse events including hallucinations, amnesia, and parasomnia more commonly reported with zolpidem in published case series, but apply to the Z-drug class; zopiclone-specific hallucination data limited in formal literature [Ref 37] - Anterograde amnesia: documented for zopiclone, especially at higher doses, and at rates higher than zaleplon (Gunja 2013 [Ref 37]) - Irritability, emotional lability, and behavioral disinhibition reported, especially in elderly patients [Refs 37, 41] **Bitter taste onset timeline:** Zopiclone's distinctive bitter-metallic taste is a pharmocokinetically-linked phenomenon, appearing in saliva before any sedative effects are maximal (~24 minutes post-dose) and correlating with plasma/saliva drug levels [Ref 5]. This is consistent across the racemate and S-enantiomer (Doty et al. 2009). --- ## Safety & Toxicity ### Therapeutic Index and Overdose Published LD50 data for zopiclone in humans is not available in the published clinical literature. Animal studies exist (Gaillot et al. 1983 [Ref 3]) but species-specific toxicity data was not fully reported in available abstracts. **Clinical overdose presentations (Gunja 2013 [Ref 37]):** - Predominantly sedation and coma - Respiratory depression possible - Supportive management is adequate in the majority of cases - **Flumazenil (benzodiazepine antagonist) has been reported to reverse sedation** from all three Z-drugs, consistent with their mechanism of action at the BZD binding site - Deaths from Z-drugs alone are rare; **mortality is substantially more likely in polydrug overdose** [Ref 37] **Post-mortem data:** - In one forensic case, zopiclone was detected at 0.043 mg/L in peripheral blood — within therapeutic range — in the context of fatal mitragynine/7-OH-mitragynine poisoning, demonstrating zopiclone's detection in post-mortem specimens (Karinen et al. 2014 [Ref: PMID 25453780 — see citation 48 below]) - In a fatal multidrug bezoar case, zopiclone was detected at 1,200 mcg/L in femoral blood at toxic concentrations alongside multiple other CNS depressants (Drevin et al. 2024 [Ref 49 below]) - Jones et al. (2016 [Ref 50 below]) compiled post-mortem femoral blood concentrations of drugs in single-drug fatalities vs. multi-drug poisoning deaths; zopiclone cited in database **Pharmacovigilance:** - EudraVigilance analysis (Schifano et al. 2019 [Ref 43]): 9,283 zopiclone-associated adverse drug reactions across 6,246 unique patients identified in European database. Zopiclone presented the **same dependence risk as zolpidem** but was **most involved in overdose adverse drug reactions** among the three Z-drugs studied. ### Organ Toxicity - **Respiratory:** Published polysomnographic data show no detrimental effects on respiratory indices at therapeutic doses (Eligulashvili et al. 1997 [Ref 18]; Musch & Maillard 1990 [Ref 16]). The brief's "acute toxicity: high" notation conflicts with published literature suggesting zopiclone has a better respiratory safety profile than barbiturates, though less so than orexin antagonists. **FLAG: "Acute toxicity: high" in seed data appears to contradict published literature characterizing zopiclone as having relatively low acute toxicity as a single agent. Needs editorial review.** - **Hepatic:** No major liver toxicity reported for racemic zopiclone at therapeutic doses. An acute liver injury case was published for eszopiclone in a patient with pre-existing chronic liver disease (Wu et al. 2021 [Ref: PMID 34160387]). Given eszopiclone is the active enantiomer, risk exists but appears rare. ### Cardiovascular No specific data found on cardiac effects. QTc data not identified in literature search for zopiclone specifically. --- ## Harm Reduction ### Contraindications from Published Sources 1. **Concurrent CNS depressants:** Additive/synergistic sedation and respiratory depression with alcohol (Kuitunen et al. 1990 [Ref 36]; Hesse et al. 2003 [Ref 35]), opioids, benzodiazepines, other sedatives, antihistamines, antipsychotics. 2. **Driving and operating machinery:** Patients should be counseled to avoid driving for at least 8–10 hours post-dose given zopiclone 7.5 mg's documented residual impairment lasting up to 10 hours (Patat 2001 [Ref 24]; Gunja 2013 [Ref 37]). 3. **Pregnancy:** Not well-studied in humans. Animal data shows excretion in breast milk (milk/plasma ratio ~0.80), making breastfeeding a contraindication (Gaillot et al. 1983 [Ref 3]). 4. **Hepatic impairment:** Significantly prolonged half-life and elevated plasma concentrations; dose reduction to 3.5 mg mandatory in severe hepatic insufficiency (Gaillot et al. 1987 [Ref 2]). 5. **Elderly patients:** Significantly altered pharmacokinetics; half-life nearly doubled; falls and cognitive impairment risk substantially elevated (Glass et al. 2005 [Ref 34]; Louzada et al. 2021 [Ref 40]). 6. **History of substance use disorder:** Patients with substance abuse history at elevated risk of dependence (Schifano et al. 2019 [Ref 43]; Cimolai 2007 [Ref 10]). 7. **Respiratory insufficiency:** Caution advised given GABA-A modulator mechanism; limited specific data for zopiclone in COPD/sleep apnea found in literature. ### Risk Reduction Strategies from Published Sources - **Duration limitation:** Clinical guidelines recommend maximum 2–4 weeks of use (Riemann et al. 2023 [Ref 44]; Davies et al. 2017 [Ref 8]). - **Dose reduction in elderly:** Starting dose 3.75 mg rather than 7.5 mg [Ref 2]. - **Avoid abrupt discontinuation** after chronic use to prevent rebound insomnia and withdrawal symptoms. - **Flumazenil** available as reversal agent in overdose contexts [Ref 37]. - **Testing:** Zopiclone can be detected via LC-MS in blood, urine, oral fluid, and post-mortem specimens. No colorimetric reagent test strips exist specifically for zopiclone as a harm reduction tool [Ref 37]. --- ## Tolerance & Dependence ### Tolerance Early clinical studies (Fleming et al. 1988 [Ref 17]) demonstrated that zopiclone maintained hypnotic effectiveness over 17 weeks of continuous use without evidence of tolerance developing to sleep-promoting effects. Similar findings for the S-enantiomer (eszopiclone) at 3 mg for up to 12 months (Monti & Pandi-Perumal 2007 [Ref 30]). However, the clinical consensus notes that tolerance to the hypnotic effects of benzodiazepines and Z-drugs generally develops within 3–4 weeks (Touitou 2007 [Ref cited in prior searches]; Barbera & Shapiro 2005 [Ref previously cited]). **Seed data cross-tolerance claim (benzodiazepines):** Confirmed — zopiclone acts at the same GABA-A benzodiazepine binding site; cross-tolerance with benzodiazepines is pharmacologically expected and consistent with published literature [Refs 15, 38]. **Tolerance buildup timeline (seed data: "within a couple of weeks of daily use"):** Consistent with published literature for the class. No specific controlled study quantifying zopiclone tolerance onset was identified in this search. **Full reset: 10.5 days (seed data):** This specific value was not verified in published literature during this search. The claim appears to be an approximation based on 5× half-life calculations (~5.5h × 5 = ~27.5h for the drug to clear) combined with receptor upregulation timelines, but was not found in a specific published study. **FLAG: Seed value "full reset 10.5 days" not verified against a primary source. Needs editorial review.** ### Dependence Published literature confirms dependence potential: - Case reports of dependence documented (Guo & Zhou 2025 [Ref 6]) - EudraVigilance data: zopiclone presents the same dependence risk as zolpidem (Schifano et al. 2019 [Ref 43]) - Abuse and misuse documented in addiction service populations (Curreen & Lidmila 2014 [Ref 9]; Cimolai 2007 [Ref 10]) **Compared to benzodiazepines:** Published literature consistently characterizes zopiclone as having a *lower* dependence and abuse potential than benzodiazepines (Goa & Heel 1986 [Ref 15]; Barbera & Shapiro 2005 [Ref 15 context]; Hesse et al. 2003 [Ref 35]). The brief's seed characterization of zopiclone as "extremely physically and psychologically addictive" is not well-supported by the published literature, which typically describes moderate dependence potential. **FLAG: "Extremely physically and psychologically addictive" appears to overstate the published evidence. Most sources describe a lower dependence potential than BZDs but real addictive liability in vulnerable populations.** **Withdrawal:** After chronic use, discontinuation is associated with rebound insomnia and withdrawal symptoms including anxiety, abnormal dreams, and nausea (Monti & Pandi-Perumal 2007 [Ref 30]; Lader 2012 [PMID 22882333]). Comparison studies (Pchelina et al. 2017 [Ref 29]) confirmed that zopiclone benefits did not persist after stopping treatment (vs. CBT-I, whose benefits were maintained). --- ## Interactions ### CYP3A4 Interactions (Hesse et al. 2003 [Ref 35]; Chouinard et al. 1999 [Ref 25]; Dresser et al. 2000 [Ref 26]; Fernandez et al. 1995 [Ref 1]) **CYP3A4 Inhibitors (increase zopiclone levels/effect):** - Erythromycin: increases zopiclone exposure; enhanced sedation [Refs 1, 25, 35] - Ketoconazole, itraconazole, other azole antifungals: CYP3A4 inhibition; dose reduction may be required [Refs 26, 35] - Clarithromycin, nefazodone, ritonavir: similar interaction expected [Ref 26] - Cimetidine (H2 antagonist): inhibits zopiclone metabolism [Ref 35] - Grapefruit juice: CYP3A4 inhibition possible [Ref 26] **CYP3A4 Inducers (decrease zopiclone levels/effect):** - Rifampicin: significantly induces metabolism, decreased sedative effects; dose increase may be needed [Ref 35] - Carbamazepine: reported interaction; metabolic induction [Refs 1, 25] **Pharmacodynamic Interactions:** - **Alcohol:** Additive CNS depressant effects; zopiclone peak effects enhanced and prolonged. Pharmacokinetic parameters of zopiclone not substantially altered by alcohol (no pharmacokinetic interaction), but pharmacodynamic effects are clearly additive and potentially dangerous (Kuitunen et al. 1990 [Ref 36]; Hesse et al. 2003 [Ref 35]). - **Trimipramine:** Zopiclone decreased trimipramine bioavailability by ~26.6% (Caille et al. 1984 [Ref 5]; Fernandez et al. 1995 [Ref 1]); clinical significance uncertain. - **Other CNS depressants (opioids, benzodiazepines, antipsychotics, antihistamines, sedating antidepressants):** Additive sedation and respiratory depression risk [Refs 26, 35, 37]. **Lethality risk:** The brief correctly notes potential lethality when mixed with depressants. Published forensic data confirm polydrug overdose is the principal context for fatality (Gunja 2013 [Ref 37]). --- ## Legal Status | Jurisdiction | Status | Schedule/Classification | Notes | |---|---|---|---| | United States | DEA Schedule IV | Controlled Substances Act | Final rule effective April 4, 2005 [Refs 27, 33]. Not commercially marketed — only eszopiclone (Lunesta) available. | | United Kingdom | Schedule 4, Part I | Misuse of Drugs Act 1971 | Prescription-only medicine (POM). | | Canada | Schedule IV | Controlled Drugs and Substances Act (CDSA) | Available by prescription; generics widely available. | | New Zealand | Class C5 | Misuse of Drugs Act (amendment 2022) | Was prescription medicine; rescheduled as controlled drug. | | Australia | Schedule 4 (prescription only) | Therapeutic Goods Act | Imovane distributed by Sanofi-Aventis. | | European Union | Prescription only | National regulations vary | Widely available across EU countries. | | Brazil | Prescription controlled | ANVISA | Available. | **Note on web-sourced legal data:** Jurisdiction-specific legal status information was drawn primarily from web sources (DEA Federal Register, government websites). Australian Schedule was confirmed as S4 from web sources but not via a government regulatory database API. All legal status data should be verified at time of article publication. --- ## Clinical Trials ### Directly Relevant Trials Identified **NCT03075241 — Zopiclone in Alzheimer's Disease (completed)** - Sponsor: University of Brasília - Phase: Not specified (peer-reviewed RCT published in Neuropsychopharmacology 2022) - Zopiclone 7.5 mg/day vs. zolpidem 10 mg/day vs. placebo, 62 patients, 14-day treatment - Key finding: Zopiclone improved sleep duration (+81 min MNSD) and WASO (-26 min) vs. placebo; 3 participants discontinued due to intense sedation and worsened agitation (Louzada et al. 2022 [Ref 41]) **NCT02807922 — Pharmacological Treatment of Insomnia in Palliative Care (Phase 4, completed)** - Sponsor: St. Olavs Hospital, Norway - Conditions: Insomnia in palliative care patients - Zopiclone included as pharmacological intervention **NCT02570581 — MELA Study: Hedonic study on taste of drugs crushed in food (Phase 1, completed)** - Sponsor: CHU de Nice, France - Conditions: Healthy volunteers - Directly relevant to zopiclone's documented bitter taste adverse effect ### Notes on Clinical Trial Coverage The majority of registered clinical trials for the cyclopyrrolone class concern eszopiclone (the US-approved enantiomer), not racemic zopiclone. This reflects the US market structure (only eszopiclone marketed in USA). Historical RCTs supporting zopiclone's approval were conducted in Europe and Canada in the 1980s–1990s, predating ClinicalTrials.gov registration requirements; these appear only in peer-reviewed literature, not as registered trials. --- ## Community Feedback Analysis No community feedback was submitted for this substance (Part A2 was empty). --- ## Gaps & Flags ### Safety-Critical Flags for Human Review 1. **⚠️ FLAG — Seed toxicity data contradiction:** The brief states "Acute: high; Chronic: high" for toxicity AND "Notes: low toxicity" in the same field. These are contradictory. Published literature consistently characterizes zopiclone as having relatively low acute toxicity as a monodrug; lethality occurs predominantly in polydrug overdose. Recommend editorial resolution. 2. **⚠️ FLAG — "Extremely physically and psychologically addictive" overstates published evidence:** Published literature describes zopiclone's dependence potential as real but generally lower than benzodiazepines. Multiple review articles specifically contrast zopiclone's dependence risk favorably against benzodiazepines. "Extremely" addictive is not supported. Recommend revising to "physically and psychologically addictive, with dependence potential lower than benzodiazepines but clinically significant with prolonged use." 3. **⚠️ FLAG — Tolerance full reset value "10.5 days" not verified:** No primary published source was identified for this specific value. It may derive from receptor normalization studies (which are not zopiclone-specific) or from pharmacokinetic extrapolation. Recommend editorial verification or removal if unsourced. 4. **⚠️ FLAG — Australian scheduling not confirmed via primary regulatory source:** Web sources indicate zopiclone is Schedule 4 (prescription only) in Australia via Therapeutic Goods Administration, but a TGA database lookup was not performed. Verify before publication. 5. **⚠️ FLAG — Breastfeeding contraindication:** Zopiclone distributes into breast milk (milk/plasma ratio ~0.80). This should be explicitly included in contraindications; it was absent from the seed data contraindications field. 6. **⚠️ FLAG — No LD50 human data identified:** No published human LD50 or therapeutic index data was found for zopiclone. Animal data exists from the 1983 preclinical studies but was not fully reported in available abstracts. 7. **⚠️ FLAG — SMILES string needs direct PubChem API verification:** PubChem canonical SMILES for CID 5735 should be fetched directly and included in the database record; the string above is reconstructed for reference. ### Data Gaps - **CYP enzymes beyond CYP3A4:** Zopiclone is metabolized by multiple CYP enzymes in addition to CYP3A4, but the specific additional isozymes were not identified in available abstracts. - **Specific Ki or EC50 values at GABA-A subunit combinations:** No published binding affinity data tables (Ki values) for zopiclone at specific GABA-A subunit combinations were identified. The 2008 Hanson study (eszopiclone) is the closest published structural data. - **Seizure threshold and withdrawal seizures:** While benzodiazepine withdrawal can cause seizures, zopiclone-specific withdrawal seizure data was not identified in this search. - **Long-term sleep architecture data:** Most polysomnographic studies are short-term (2–17 weeks); long-term effects on REM and SWS not well characterized for zopiclone specifically. - **Specific hallucination incidence data for zopiclone:** Effect profile includes auditory-hallucinations, external-hallucinations, visual-drifting, shadow-people, etc. These are supported by class-level data (Z-drug hallucination literature) and Gunja 2013, but zopiclone-specific incidence figures were not found. - **Recreational use characterization:** Zopiclone is mentioned in abuse/misuse literature but specific recreational dose ranges, routes beyond oral, and experiential accounts beyond the clinical setting are not well-documented in peer-reviewed literature. - **Effect profile intensity/frequency values:** All 24 seed effect slugs lack intensity and frequency values. These should be informed by the pharmacodynamic literature assembled above (e.g., sedation = high intensity/very common; bitter taste not in effect taxonomy but metallic taste may map to gustatory-hallucination at low intensity).