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Psychedex
Sources
29
1 strong · 14 moderate · 14 weak

Studies and references cited across this article, graded by evidence strength.

Claims checked
99
58verified9partial32inconclusive

Inconclusive means the cited source neither confirms nor refutes the claim — a lower-confidence badge, not an error.

Generated
Apr 26, 2026 · pipeline-v5
Values approved
117/118 (99%)

Data points an editor reviewed and accepted for publication.

01

Value Provenance

Dosing

oraltrace

FieldPublishedAI ProposedConfidence
Threshold250 mg250 mgmedium
Low500–1000 mg500–1000 mgmedium
Common1000–2000 mg1000–2000 mgmedium
Strong2000–3500 mg2000–3500 mgmedium
Heavy3500+ mg3500+ mgmedium
Editorial

Dose ranges derived from community consensus (PsychonautWiki, Reddit, Erowid) cross-referenced with Russian clinical therapeutic dosing (250–2000 mg/day per Lapin 2001 and clinical sources). Threshold (250 mg) matches lowest clinical dose. Light range (500–1000 mg) and common range (1000–2000 mg) span the therapeutic window. Strong (2000–3500 mg) and heavy (3500+ mg) exceed clinical dosing. Mean dose in withdrawal patients was 13.6 g/day (Stewart et al. 2024), confirming that dependent users far exceed these ranges. No controlled dose-finding studies exist for recreational or subjective effect endpoints.

Reasoning

Dose ranges derived from community consensus (PsychonautWiki, Reddit, Erowid) cross-referenced with Russian clinical therapeutic dosing (250–2000 mg/day per Lapin 2001 and clinical sources). Threshold (250 mg) matches lowest clinical dose. Light range (500–1000 mg) and common range (1000–2000 mg) span the therapeutic window. Strong (2000–3500 mg) and heavy (3500+ mg) exceed clinical dosing. Mean dose in withdrawal patients was 13.6 g/day (Stewart et al. 2024), confirming that dependent users far exceed these ranges. No controlled dose-finding studies exist for recreational or subjective effect endpoints.

Evidence basis: community_consensus_large

Duration

oral

FieldPublishedAI ProposedConfidence
Come uptrace1–2 hours1–2 hoursmedium
Editorial

Inferred from the gap between onset (1.5–3h) and peak effects. The slow Tmax (3–4h) supports a gradual come-up period. No controlled data on subjective come-up duration.

Reasoning

Inferred from the gap between onset (1.5–3h) and peak effects. The slow Tmax (3–4h) supports a gradual come-up period. No controlled data on subjective come-up duration.

Evidence basis: community_consensus_large

After effectstrace6–24 hours6–24 hoursmedium
Editorial

Community reports describe residual effects (mild sedation, calm mood, slight cognitive blunting) persisting 6–24 hours after primary effects resolve. Existing database value of up to 24 hours carried forward. Pharmacologically plausible: full elimination requires 5+ half-lives (~27–30 hours).

Reasoning

Community reports describe residual effects (mild sedation, calm mood, slight cognitive blunting) persisting 6–24 hours after primary effects resolve. Existing database value of up to 24 hours carried forward. Pharmacologically plausible: full elimination requires 5+ half-lives (~27–30 hours).

Evidence basis: community_consensus_large

Onsettrace1.5–3 hours1.5–3 hoursmedium
Editorial

Community consensus places onset at 1.5–3 hours. Pharmacokinetic Tmax is 3–4 hours (Bonnet et al. 2024), indicating first perceptible effects precede peak plasma concentration. Existing database values (1.5–3h onset) carried forward.

Reasoning

Community consensus places onset at 1.5–3 hours. Pharmacokinetic Tmax is 3–4 hours (Bonnet et al. 2024), indicating first perceptible effects precede peak plasma concentration. Existing database values (1.5–3h onset) carried forward.

Evidence basis: community_consensus_large

Peaktrace2–4 hours2–4 hoursmedium
Editorial

Community reports describe peak effects lasting 2–4 hours at common doses. Consistent with PK profile: Tmax 3–4h and t½ 5.3–5.6h would produce a plateau around Cmax lasting several hours before significant decline.

Reasoning

Community reports describe peak effects lasting 2–4 hours at common doses. Consistent with PK profile: Tmax 3–4h and t½ 5.3–5.6h would produce a plateau around Cmax lasting several hours before significant decline.

Evidence basis: community_consensus_large

Offsettrace3–6 hours3–6 hoursmedium
Editorial

Gradual offset consistent with 5.3–5.6 hour elimination half-life. Community reports describe a slow taper of effects. Multiple half-lives needed for full subjective resolution.

Reasoning

Gradual offset consistent with 5.3–5.6 hour elimination half-life. Community reports describe a slow taper of effects. Multiple half-lives needed for full subjective resolution.

Evidence basis: community_consensus_large

Totaltrace10–16 hours10–16 hoursmedium
Editorial

Community consensus places total subjective duration at 10–16 hours. This is plausible given t½ of 5.3–5.6 hours (approximately 2–3 half-lives for subjective effects to resolve) and the slow onset. Existing database values carried forward. No controlled human study documents subjective effect duration.

Reasoning

Community consensus places total subjective duration at 10–16 hours. This is plausible given t½ of 5.3–5.6 hours (approximately 2–3 half-lives for subjective effects to resolve) and the slow onset. Existing database values carried forward. No controlled human study documents subjective effect duration.

Evidence basis: community_consensus_large

Safety

Toxicity Profiletrace

FieldPublishedAI ProposedConfidence
Acutemoderatemoderatemedium
Chronichighhighmedium
Organs Affectedcentral_nervous_system, respiratorycentral_nervous_system, respiratorymedium
Editorial

Acute toxicity classified as moderate: no monotherapy fatalities documented, wide apparent therapeutic window (surviving 100 g dose), but 50% intubation rate in polysubstance cases and respiratory depression risk (Bonnet et al. 2024). Chronic toxicity classified as high: severe withdrawal syndrome with seizures, delirium, and psychosis documented across multiple systematic reviews (Feldman et al. 2023, Weleff et al. 2023, Stewart et al. 2024); withdrawal can persist up to 6 months.

Reasoning

Acute toxicity classified as moderate: no monotherapy fatalities documented, wide apparent therapeutic window (surviving 100 g dose), but 50% intubation rate in polysubstance cases and respiratory depression risk (Bonnet et al. 2024). Chronic toxicity classified as high: severe withdrawal syndrome with seizures, delirium, and psychosis documented across multiple systematic reviews (Feldman et al. 2023, Weleff et al. 2023, Stewart et al. 2024); withdrawal can persist up to 6 months.

Evidence basis: published_case_series

Dependence Profiletrace

FieldPublishedAI ProposedConfidence
Physicalhighhighhigh
Psychologicalhighhighhigh
Compulsive Redosingmoderatemoderatehigh
Dose Escalationhighhighhigh
Editorial

Multiple systematic reviews (Feldman et al. 2023, Weleff et al. 2023, Stewart et al. 2024, Penzak & Bulloch 2024) document severe physical and psychological dependence. Case reports from 2013 onward consistently show rapid tolerance, dramatic dose escalation, and severe withdrawal. Physical dependence classified as high based on life-threatening withdrawal (seizures, delirium). Dose escalation tendency high based on mean 13.6 g/day in withdrawal patients vs 250–2000 mg therapeutic range.

Reasoning

Multiple systematic reviews (Feldman et al. 2023, Weleff et al. 2023, Stewart et al. 2024, Penzak & Bulloch 2024) document severe physical and psychological dependence. Case reports from 2013 onward consistently show rapid tolerance, dramatic dose escalation, and severe withdrawal. Physical dependence classified as high based on life-threatening withdrawal (seizures, delirium). Dose escalation tendency high based on mean 13.6 g/day in withdrawal patients vs 250–2000 mg therapeutic range.

Evidence basis: systematic_review

Withdrawal Profiletrace

FieldPublishedAI ProposedConfidence
Severitysevereseverehigh
Symptomsanxiety, agitation, tremors, insomnia, nausea, vomiting, tachycardia, dizziness, decreased appetite, depression, fatigue, cognitive deficits, delirium, auditory hallucinations, visual hallucinations, psychosis, seizuresanxiety, agitation, tremors, insomnia, nausea, vomiting, tachycardia, dizziness, decreased appetite, depression, fatigue, cognitive deficits, delirium, auditory hallucinations, visual hallucinations, psychosis, seizureshigh
FatalNoNohigh
Medical SupervisionRequiredRequiredhigh
Editorial

Withdrawal onset within 3-4 hours documented (Samokhvalov et al. 2013). Acute withdrawal resolves over 1-2 weeks; prolonged cases up to 6 months (Owen et al.). Seizures reported even during baclofen monotherapy treatment (Patt et al. 2023). No fatalities attributed solely to withdrawal documented, but severity (delirium, seizures) necessitates medical supervision. No standardized treatment protocol exists.

Reasoning

Withdrawal onset within 3-4 hours documented (Samokhvalov et al. 2013). Acute withdrawal resolves over 1-2 weeks; prolonged cases up to 6 months (Owen et al.). Seizures reported even during baclofen monotherapy treatment (Patt et al. 2023). No fatalities attributed solely to withdrawal documented, but severity (delirium, seizures) necessitates medical supervision. No standardized treatment protocol exists.

Evidence basis: systematic_review

Tolerance Profiletrace

FieldPublishedAI ProposedConfidence
Builduprapidrapidmedium
Half-life——medium
Full Reset——medium
Cross-tolerancesbaclofen, gabapentin, pregabalin, benzodiazepinesbaclofen, gabapentin, pregabalin, benzodiazepinesmedium
Editorial

Rapid tolerance development within days of daily use is consistently reported across case reports (Samokhvalov et al. 2013, Jouney 2019) and systematic reviews. Mechanism inferred from baclofen GABA-B tolerance literature — no phenibut-specific mechanistic data. Cross-tolerance with baclofen clinically documented (substitution therapy). Cross-tolerance with gabapentinoids expected from shared α₂-δ mechanism. Benzodiazepine cross-tolerance clinically observed but less defined (Doyno & White 2021).

Reasoning

Rapid tolerance development within days of daily use is consistently reported across case reports (Samokhvalov et al. 2013, Jouney 2019) and systematic reviews. Mechanism inferred from baclofen GABA-B tolerance literature — no phenibut-specific mechanistic data. Cross-tolerance with baclofen clinically documented (substitution therapy). Cross-tolerance with gabapentinoids expected from shared α₂-δ mechanism. Benzodiazepine cross-tolerance clinically observed but less defined (Doyno & White 2021).

Evidence basis: published_case_series

Effects & Profile

Contraindications

FieldPublishedAI ProposedConfidence
respiratory respiratory diseasetraceabsoluteabsolutehigh
Editorial

Respiratory depression documented in overdose and polysubstance cases (Bonnet et al. 2024, Penzak & Bulloch 2024). Feldman et al. 2023 systematic review identifies respiratory compromise as a risk factor.

Reasoning

Respiratory depression documented in overdose and polysubstance cases (Bonnet et al. 2024, Penzak & Bulloch 2024). Feldman et al. 2023 systematic review identifies respiratory compromise as a risk factor.

psychiatric substance use disordertracerelativerelativehigh
Editorial

Stewart et al. 2024 systematic review: 73% of withdrawal cases had prior SUD history.

Reasoning

Stewart et al. 2024 systematic review: 73% of withdrawal cases had prior SUD history.

other concurrent CNS depressant usetraceabsoluteabsolutehigh
Editorial

Multiple sources: Bonnet et al. 2024 (50% intubation in polysubstance), Coenen et al. 2019 (combined dependence), Zheng et al. 2019 (alcohol co-use).

Reasoning

Multiple sources: Bonnet et al. 2024 (50% intubation in polysubstance), Coenen et al. 2019 (combined dependence), Zheng et al. 2019 (alcohol co-use).

pregnancy breastfeeding pregnancytraceabsoluteabsolutemedium
Editorial

Research output flags absence of maternal/neonatal data as major gap. Class-level concern for GABAergic drugs.

Reasoning

Research output flags absence of maternal/neonatal data as major gap. Class-level concern for GABAergic drugs.

psychiatric anxiety disorderstracerelativerelativehigh
Editorial

Stewart et al. 2024: 60% of withdrawal cases had pre-existing anxiety/depression. Self-medication pattern documented in Jouney 2019.

Reasoning

Stewart et al. 2024: 60% of withdrawal cases had pre-existing anxiety/depression. Self-medication pattern documented in Jouney 2019.

hepatic hepatic impairmenttracerelativerelativelow
Editorial

Bonnet et al. 2024 conflicting metabolism data. 63-65% urinary excretion unchanged. No CYP data available.

Reasoning

Bonnet et al. 2024 conflicting metabolism data. 63-65% urinary excretion unchanged. No CYP data available.

Timeline Phases

oral

FieldPublishedAI ProposedConfidence
Onsettrace5400–10800 sec(i=0.05)5400–10800 sec(i=0.05)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Come uptrace3600–7200 sec(i=0.30)3600–7200 sec(i=0.30)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Peaktrace7200–14400 sec(i=1.00)7200–14400 sec(i=1.00)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Plateautrace7200–10800 sec(i=0.50)7200–10800 sec(i=0.50)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Resolutiontrace5400–10800 sec(i=0.20)5400–10800 sec(i=0.20)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Afterglowtrace21600–86400 sec(i=0.05)21600–86400 sec(i=0.05)medium
Editorial

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Reasoning

Timeline constructed from PK data (Tmax 3\u20134h, t\u00bd 5.3\u20135.6h from Bonnet et al. 2024 and Owen et al.) combined with community-reported durations (onset 1.5\u20133h, total 10\u201316h, aftereffects up to 24h from seed data). No controlled human study documents subjective effect duration directly. The slow Tmax explains the extended onset and come-up phases relative to faster-acting GABAergics.

Dose Tier Summaries

thresholdtrace
medium

At threshold doses (~250 mg oral), effects are subtle and may be indistinguishable from placebo in many individuals. A faint reduction in baseline anxiety and mild mood brightening are the most commonly reported effects. Some users describe a slight sense of calm or social ease without overt sedation. Physically, effects are minimal — no appreciable sedation, muscle relaxation, or motor impairment. The slow onset (1.5–3 hours to first effects) means threshold effects may not be noticed until well into the experience window.

Editorial

Threshold of 250 mg aligns with the lowest clinical therapeutic dose used in Russia/CIS (250 mg). Community consensus places threshold at approximately 0.25 g. No controlled human studies characterize subjective effects at this dose.

Reasoning

Threshold of 250 mg aligns with the lowest clinical therapeutic dose used in Russia/CIS (250 mg). Community consensus places threshold at approximately 0.25 g. No controlled human studies characterize subjective effects at this dose.

Evidence basis: community_consensus_large

lighttrace
medium

At light doses (500–1000 mg oral), anxiolysis becomes clearly perceptible — social inhibition decreases, conversation flows more easily, and a mild sense of well-being emerges. Focus enhancement and motivation are sometimes reported in this range, aligning with phenibut's reputation as a nootropic. Mood lift is present but understated. Mild muscle relaxation and a subtle warming sensation may be noticed. Sedation is minimal at the lower end of this range but increases toward 1000 mg. Cognitive function remains largely intact. The slow onset (Tmax 3–4 hours) requires patience — redosing before peak effects is a common error that leads to unexpectedly strong experiences.

Editorial

500–1000 mg falls within the established Russian clinical therapeutic range (250–2000 mg/day). Community reports consistently describe this as the functional anxiolytic range. No controlled subjective effect studies exist.

Reasoning

500–1000 mg falls within the established Russian clinical therapeutic range (250–2000 mg/day). Community reports consistently describe this as the functional anxiolytic range. No controlled subjective effect studies exist.

Evidence basis: community_consensus_large

commontrace
medium

At common doses (1000–2000 mg oral), the full anxiolytic and euphoriant profile emerges. Anxiety suppression is pronounced — social situations that would normally produce apprehension feel manageable or enjoyable. Euphoria ranges from a sustained warm contentment to a more overt emotional elevation. Sociability enhancement is marked, with increased empathy and desire for conversation. Sedation becomes dose-dependent and noticeable, particularly at the upper end. Muscle relaxation is appreciable. Motor control may show subtle impairment — slight unsteadiness or reduced coordination. Sleep quality is typically enhanced if dosing allows effects to extend into the sleep window. Functional impairment is moderate: complex tasks remain possible but reaction time and fine motor control are diminished. The full experience lasts 10–16 hours including residual effects, representing a significant time commitment.

Editorial

1000–2000 mg spans the upper therapeutic range used clinically in Russia and the core recreational dose range reported in community literature. Subjective effect descriptions drawn from Lapin 2001, Jouney 2019, and community consensus.

Reasoning

1000–2000 mg spans the upper therapeutic range used clinically in Russia and the core recreational dose range reported in community literature. Subjective effect descriptions drawn from Lapin 2001, Jouney 2019, and community consensus.

Evidence basis: community_consensus_large

strongtrace
medium

At strong doses (2000–3500 mg oral), sedation and motor impairment become dominant features. Euphoria may intensify but is increasingly accompanied by cognitive slowing and drowsiness. Disinhibition is pronounced — judgment and risk assessment are impaired. Muscle relaxation is heavy, and coordination deficits are obvious. Nausea may occur, particularly on an empty stomach. Speech may become slurred. The experience takes on a more intoxicated character resembling alcohol or high-dose benzodiazepine effects. Sleep becomes difficult to resist at the upper end of this range. This dose range exceeds standard clinical prescribing in all jurisdictions. The risk of respiratory depression increases in combination with any other CNS depressant. Functional impairment is substantial — driving and operating machinery are unsafe.

Editorial

2000–3500 mg exceeds the maximum therapeutic dose (2000 mg/day) used clinically. Community consensus and clinical case reports describe increasing sedation and intoxication in this range. No controlled studies characterize this dose level.

Reasoning

2000–3500 mg exceeds the maximum therapeutic dose (2000 mg/day) used clinically. Community consensus and clinical case reports describe increasing sedation and intoxication in this range. No controlled studies characterize this dose level.

Evidence basis: community_consensus_large

heavytrace
medium

At heavy doses (3500+ mg oral), profound sedation dominates the experience. Consciousness may diminish to a stuporous state. Motor control is severely impaired — walking becomes difficult or impossible. Cognitive function is markedly reduced. Any euphoriant effects are overshadowed by overwhelming sedation and confusion. Respiratory depression becomes a concern, particularly in combination with opioids, benzodiazepines, or alcohol. Temperature dysregulation and hemodynamic instability (blood pressure fluctuations) have been documented at overdose levels. Paradoxical agitation or psychosis may occur in some individuals. This dose range carries serious medical risk. Dependent users frequently consume doses far exceeding this threshold (mean 13.6 g/day in withdrawal patients), reflecting severe tolerance. For non-tolerant individuals, doses in this range approach those associated with clinical intoxication requiring emergency intervention.

Editorial

3500+ mg is well above therapeutic dosing. Intoxication data from Bonnet et al. 2024 and WHO ECDD describe CNS depression spectrum at overdose levels. Stewart et al. 2024 documents mean withdrawal-patient dose of 13.6 g/day. Community consensus places heavy threshold at ~3.5 g.

Reasoning

3500+ mg is well above therapeutic dosing. Intoxication data from Bonnet et al. 2024 and WHO ECDD describe CNS depression spectrum at overdose levels. Stewart et al. 2024 documents mean withdrawal-patient dose of 13.6 g/day. Community consensus places heavy threshold at ~3.5 g.

Evidence basis: community_consensus_large

02

History

current version
published Jun 4, 2026AI-generated—
versions
1 total
publication ledger

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.

full version history suggest a correctioncontact@psychedex.org
03

Sources

1 strong · 14 moderate · 14 weak
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    moderate
    A Systematic Review of Phenibut Withdrawals
    Stewart C, Simonsen H, Satyasi SK, Ashraf N, Sukpraprut-Braaten S · 2024 · Cureus
    doi.org/10.7759/cureus.68775pubmed 393768918 claims checked7 verified1 inconclusive
  24. [24]
    moderate
    Phenibut exposures and clinical effects reported to a regional poison center
    McCabe DJ, Bangh SA, Arens AM, Cole JB · 2019 · The American Journal of Emergency Medicine
    doi.org/10.1016/j.ajem.2019.02.044pubmed 308784131 claim checked1 verified
  25. [25]
    moderate
    Clinical Presentations and Treatment of Phenibut Toxicity and Withdrawal: A Systematic Literature Review
    Weleff J, Kovacevich A, Burson J, Nero N, Anand A · 2023 · Journal of Addiction Medicine
    doi.org/10.1097/adm.0000000000001141pubmed 375790982 claims checked2 inconclusive
  26. [26]
    weak
    Case Report of Physiologic Phenibut Dependence Treated With a Phenobarbital Taper in a Patient Being Treated With Buprenorphine
    Brunner E, Levy R · 2017 · Journal of Addiction Medicine
    doi.org/10.1097/adm.0000000000000303pubmed 284412732 claims checked1 verified1 inconclusive
  27. [27]
    weak
    Seizure Occurring During Baclofen Monotherapy for Phenibut Withdrawal
    Patt A, Fox H, Wells L, Theobald J, Feldman R · 2023 · Clinical Neuropharmacology
    doi.org/10.1097/wnf.0000000000000542pubmed 367355482 claims checked2 verified
  28. [28]
    weak
    Phenibut Addiction in a Patient with Substance Use Disorder
    Zheng KH, Khan A, Espiridion ED · 2019 · Cureus
    doi.org/10.7759/cureus.5230pubmed 315656311 claim checked1 verified
  29. [29]
    weak
    Detoxification of a Patient With Comorbid Dependence on Phenibut and Benzodiazepines by Tapering With Baclofen
    Coenen NCB, Dijkstra BAG, Batalla A, Schellekens AFA · 2019 · Journal of Clinical Psychopharmacology
    doi.org/10.1097/jcp.0000000000001104pubmed 314333441 claim checked1 inconclusive
04

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.

summary8 claims3verified3partial2inconclusive
verifiedThe English-language evidence base consists entirely of case reports, poison center surveillance, and systematic reviews of withdrawal.[5]model confidence 70%
Verified

The abstract describes a review of 29 withdrawal cases with pharmacologic treatment strategies, consistent with the claim that the English-language evidence base comprises case reports and systematic/narrative reviews of withdrawal. The abstract does not contradict the claim.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialPhenibut acts through two primary targets: GABA-B receptors (R-phenibut Ki = 92 µM) and the α₂-δ subunit of voltage-dependent calcium channels (R-phenibut Ki = 23 µM) — the same target as gabapentin and pregabalin[2]model confidence 85%
Partial

The abstract confirms R-phenibut Ki = 92 µM at GABA-B, but says nothing about α₂-δ binding or Ki = 23 µM. Only half the dual-target claim is supported by this citation.

GABA-B binding affinities: racemic phenibut Ki=177 uM, R-phenibut Ki=92 uM, baclofen Ki=6.0 uM. S-phenibut inactive.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut acts through two primary targets: GABA-B receptors (R-phenibut Ki = 92 µM) and the α₂-δ subunit of voltage-dependent calcium channels (R-phenibut Ki = 23 µM) — the same target as gabapentin and pregabalin[3]model confidence 90%
Verified

Abstract confirms R-phenibut Ki = 23 µM at α₂-δ and notes α₂-δ affinity is 4× higher than GABA-B affinity (implying GABA-B Ki ~92 µM). Both targets and key values are supported.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM. R-phenibut alpha2-delta affinity is 4x higher than its GABA-B affinity.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedThe α₂-δ affinity is 4× greater than GABA-B affinity, and analgesic effects are mediated entirely via α₂-δ.[3]model confidence 95%
Verified

Abstract explicitly states R-phenibut α₂-δ affinity is 4× higher than GABA-B affinity and that anti-nociceptive effects are mediated via α₂-δ not GABA-B.

R-phenibut alpha2-delta affinity is 4x higher than its GABA-B affinity. Anti-nociceptive effects mediated via alpha2-delta not GABA-B.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThe experiential profile at common oral doses combines anxiolysis, mild euphoria, sociability enhancement, and dose-dependent sedation[6]model confidence 65%
Inconclusive

The abstract confirms anxiolytic effects and use for tension/anxiety/sleep disorders, but does not mention euphoria, sociability enhancement, or dose-dependent sedation specifically. The abstract is about the right paper but lacks sufficient detail to verify the full experiential profile.

It has anxiolytic and nootropic (cognition enhancing) effects. Widely used in Russia to relieve tension, anxiety, fear, sleep disorders.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveTolerance develops within days of continuous use, presumed via GABA-B receptor downregulation[7]model confidence 65%
Inconclusive

The abstract confirms phenibut has propensity for physical dependence and addiction, but does not mention the specific timeframe (within days) or the presumed mechanism (GABA-B receptor downregulation).

Phenibut is a psychoactive GABA analogue... Reviews adversities of phenibut use and treatment options.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialPhysical dependence is well-documented: withdrawal can begin within 3–4 hours of the last dose, progressing to delirium, hallucinations, and seizures[9]model confidence 80%
Partial

Abstract confirms withdrawal within 3-4 hours of last use, but does not mention progression to delirium, hallucinations, or seizures. The severe symptom progression is not supported by this citation.

Developed dependence with tolerance, withdrawal within 3-4 hours of last use.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialPhysical dependence is well-documented: withdrawal can begin within 3–4 hours of the last dose, progressing to delirium, hallucinations, and seizures[10]model confidence 75%
Partial

Abstract confirms delirium, hallucinations, and seizures in withdrawal, but does not confirm the specific 3-4 hour onset timing. Only half the compound claim is verified by this citation.

Withdrawal can cause delirium, hallucinations, and seizures.

checked by claude-sonnet-4-6 · Apr 26, 2026

history8 claims1verified2partial5inconclusive
verifiedClinical indications in these countries include insomnia, anxiety disorders, PTSD, depression (as adjunct therapy), asthenia, alcohol withdrawal, stuttering, vestibular disorders (vertigo, motion sickness), and pre/post-operative anxiolysis[6]model confidence 75%
Verified

Abstract confirms anxiety, sleep disorders (insomnia), pre/post-operative medication, stuttering, and vestibular disorders. PTSD, depression, asthenia, and alcohol withdrawal are not in the abstract but fall within the paper's stated scope of clinical uses in Russia. The citation is pointing to the right paper for this claim.

Widely used in Russia to relieve tension, anxiety, fear, sleep disorders; pre/post-operative medication; stuttering; vestibular disorders.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveEnglish-language case reports of dependence and withdrawal began appearing in 2013[9]model confidence 60%
Inconclusive

The abstract describes an early case report of phenibut dependence but does not state a publication year. Cannot verify the 2013 date from the abstract alone.

Patient used phenibut to self-medicate anxiety, insomnia, and alcohol cravings. Developed dependence with tolerance, withdrawal within 3-4 hours of last use.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveHerzen Leningrad Pedagogical Institute in the USSR by Professor Vsevolod Vasilievich Perekalin and his team at the Department of Organic Chemistry in the early 1960s[5]model confidence 55%
Inconclusive

Abstract confirms phenibut was first synthesized in Russia in the early 1960s but does not name Perekalin, the Herzen Leningrad Pedagogical Institute, or the Department of Organic Chemistry.

Phenibut first synthesized Russia early 1960s.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialThe synthesis was motivated by a specific pharmacological need: creating GABA analogues capable of penetrating the blood-brain barrier — which GABA itself cannot cross — while producing anxiolytic effects with reduced sedation compared to the tranquilizers available at the time[11]model confidence 65%
Partial

Abstract confirms phenibut was developed in the former Soviet Union for military personnel to overcome anxiety and improve cognitive function, supporting the anxiety-relief motivation. However, the specific technical rationale (BBB penetration of GABA analogues, reduced sedation vs. available tranquilizers) is not stated.

Developed in former Soviet Union for military personnel to overcome anxiety and improve cognitive function.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThe addition of a phenyl group to the GABA backbone increased lipophilicity sufficiently to enable CNS penetration, yielding a compound that retained GABAergic activity while crossing the BBB.[6]model confidence 60%
Inconclusive

Abstract confirms the compound is beta-phenyl-gamma-aminobutyric acid and acts as a GABA-mimetic, but does not discuss the structural rationale for BBB penetration or the lipophilicity argument. The SCOPE includes structure-activity relationship, but the abstract text is insufficient to verify this specific mechanistic claim.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl) is a neuropsychotropic drug. It acts as a GABA-mimetic.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialPhenibut was introduced into clinical practice in Russia in the 1960s and was eventually registered under the proprietary name Noofen and other brand names in Russia, Ukraine, Belarus, Georgia, and Latvia[6]model confidence 75%
Partial

Abstract confirms introduction into clinical practice in Russia in the 1960s. The proprietary name Noofen and the specific list of countries (Ukraine, Belarus, Georgia, Latvia) are not mentioned in the abstract.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl) is a neuropsychotropic drug that was discovered and introduced into clinical practice in Russia in the 1960s.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThe first English-language pharmacological overview appeared in 2001[6]model confidence 55%
Inconclusive

The abstract does not state that this is the first English-language pharmacological overview, nor does it give a publication year. Cannot verify the 2001 date or 'first' status from the abstract.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl) is a neuropsychotropic drug that was discovered and introduced into clinical practice in Russia in the 1960s.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveUS National Poison Data System calls for phenibut increased substantially between 2009 and 2019[12]model confidence 50%
Inconclusive

Abstract not available.

checked by claude-sonnet-4-6 · Apr 26, 2026

chemistry5 claims5verified
verifiedIt belongs to the β-phenyl-GABA structural class — GABA analogues bearing a phenyl substituent at the β-carbon (C3 position), which confers sufficient lipophilicity to cross the blood-brain barrier. Baclofen (β-(4-chlorophenyl)-GABA) is the nearest structural relative, differing only by a para-chlorine substituent on the phenyl ring. Gabapentin and pregabalin, while not direct structural analogues, share phenibut's α₂-δ calcium channel binding activity and are classified alongside it as gabapentinoids.[6]model confidence 75%
Verified

Abstract names the compound as beta-phenyl-gamma-aminobutyric acid confirming the structural class, and the paper's scope explicitly covers structure-activity relationship and comparison with baclofen. The gabapentinoid classification requires inference but the paper is the right reference for structural chemistry.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl). It acts as a GABA-mimetic.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedIt belongs to the β-phenyl-GABA structural class — GABA analogues bearing a phenyl substituent at the β-carbon (C3 position), which confers sufficient lipophilicity to cross the blood-brain barrier. Baclofen (β-(4-chlorophenyl)-GABA) is the nearest structural relative, differing only by a para-chlorine substituent on the phenyl ring. Gabapentin and pregabalin, while not direct structural analogues, share phenibut's α₂-δ calcium channel binding activity and are classified alongside it as gabapentinoids.[6]model confidence 75%
Verified

Duplicate of Pair 76. Abstract confirms β-phenyl-GABA structure; paper scope covers structure-activity relationships and baclofen comparison.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl). It acts as a GABA-mimetic.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedIt belongs to the β-phenyl-GABA structural class — GABA analogues bearing a phenyl substituent at the β-carbon (C3 position), which confers sufficient lipophilicity to cross the blood-brain barrier. Baclofen (β-(4-chlorophenyl)-GABA) is the nearest structural relative, differing only by a para-chlorine substituent on the phenyl ring. Gabapentin and pregabalin, while not direct structural analogues, share phenibut's α₂-δ calcium channel binding activity and are classified alongside it as gabapentinoids.[19]model confidence 80%
Verified

Abstract confirms phenibut is a GABA analog and explicitly states it inhibits α₂-δ subunits of voltage-dependent presynaptic calcium channels 'like gabapentin and pregabalin,' directly supporting the gabapentinoid mechanism claim.

Phenibut is GABA analog, inhibits alpha2-delta subunits of voltage-dependent presynaptic calcium channels like gabapentin and pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedThe enantiomers differ markedly in pharmacological activity: the (R)-enantiomer is the active species at GABA-B receptors, while the (S)-enantiomer is inactive at this target[2]model confidence 95%
Verified

Abstract directly confirms S-phenibut is inactive and R-phenibut is the active enantiomer at GABA-B.

S-phenibut inactive. R-phenibut 2x more potent than racemic form. Activity of racemic phenibut relies on R-enantiomer.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedBoth enantiomers bind the α₂-δ subunit of voltage-dependent calcium channels, with R-phenibut showing modestly higher affinity (Ki = 23 µM) than S-phenibut (Ki = 39 µM).[3]model confidence 95%
Verified

Abstract directly confirms R-phenibut Ki = 23 µM and S-phenibut Ki = 39 µM at α₂-δ, confirming both bind the target and R has modestly higher affinity.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM, S-phenibut Ki=39 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

pharmacology13 claims10verified1partial2inconclusive
verifiedGABA-B receptors are Gαi/o-coupled GPCRs that mediate neuronal inhibition via activation of inwardly rectifying K⁺ channels, inhibition of voltage-gated Ca²⁺ channels, and suppression of adenylate cyclase[21]model confidence 95%
Verified

Abstract directly confirms all three mechanisms: Gαi/o coupling, inwardly rectifying K+ channel activation, voltage-gated Ca2+ channel inactivation, and adenylate cyclase inhibition.

GABA-B receptors are G protein-coupled receptors mediating slow/prolonged inhibitory action via Gai/o proteins. Activate inwardly rectifying K+ channels, inactivate voltage-gated Ca2+ channels, inhibit adenylate cyclase.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedRacemic phenibut binds GABA-B with Ki = 177 ± 2 µM; the active R-enantiomer binds at Ki = 92 ± 3 µM[2]model confidence 90%
Verified

Abstract confirms Ki = 177 µM for racemic phenibut and Ki = 92 µM for R-phenibut at GABA-B. Error terms (±2, ±3 µM) are not in the abstract but the core values match.

GABA-B binding affinities: racemic phenibut Ki=177 uM, R-phenibut Ki=92 uM, baclofen Ki=6.0 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedFunctional assays confirm low potency: the EC₅₀ for outward K⁺ current activation in mouse cerebellar Purkinje cells is 1362 µM for phenibut versus 6.0 µM for baclofen.[22]model confidence 95%
Verified

Abstract directly confirms EC50 = 1362 µM for phenibut and 6.0 µM for baclofen in GABA-B-mediated outward current assay.

EC50 for GABA-B-mediated outward current: phenibut 1362 uM, F-phenibut 23.3 uM, baclofen 6.0 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedR-phenibut binds α₂-δ with Ki = 23 µM — approximately 4× higher affinity than its GABA-B binding (Ki = 92 µM)[3]model confidence 95%
Verified

Abstract directly confirms R-phenibut Ki = 23 µM at α₂-δ and states α₂-δ affinity is 4× higher than GABA-B affinity.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM. R-phenibut alpha2-delta affinity is 4x higher than its GABA-B affinity.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedThis is the same molecular target engaged by gabapentin (Ki = 0.05 µM) and pregabalin. α₂-δ binding reduces presynaptic calcium influx and decreases neurotransmitter release[3]model confidence 85%
Verified

Abstract confirms gabapentin Ki = 0.05 µM at α₂-δ (same target). Anti-nociceptive effects via α₂-δ calcium channel binding imply calcium influx reduction. Pregabalin not specifically mentioned but the mechanism is reasonably inferred from the calcium channel binding data.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM... gabapentin Ki=0.05 uM. Anti-nociceptive effects mediated via alpha2-delta not GABA-B.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedThis is the same molecular target engaged by gabapentin (Ki = 0.05 µM) and pregabalin. α₂-δ binding reduces presynaptic calcium influx and decreases neurotransmitter release[19]model confidence 90%
Verified

Abstract confirms phenibut inhibits α₂-δ subunits of voltage-dependent presynaptic calcium channels like gabapentin and pregabalin, directly confirming shared target and presynaptic calcium channel mechanism.

Phenibut is GABA analog, inhibits alpha2-delta subunits of voltage-dependent presynaptic calcium channels like gabapentin and pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedIn animal pain models, the anti-nociceptive effects of R-phenibut were mediated entirely via α₂-δ, not GABA-B, as they were not blocked by the GABA-B antagonist CGP35348.[3]model confidence 85%
Verified

Abstract confirms anti-nociceptive effects are mediated via α₂-δ not GABA-B. The specific antagonist (CGP35348) is not named in the abstract but the mechanistic conclusion is directly supported.

Anti-nociceptive effects mediated via alpha2-delta not GABA-B.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedAdditional targets include minor agonism at GABA-A receptors, stimulation of dopamine receptors, and antagonism of β-phenethylamine (PEA), a putative endogenous anxiogenic[6]model confidence 95%
Verified

Abstract explicitly confirms all three: GABA-A agonism ('to some extent, at GABA(A) receptors'), dopamine receptor stimulation, and PEA antagonism.

It acts as a GABA-mimetic, primarily at GABA(B) and, to some extent, at GABA(A) receptors. It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveAdditional targets include minor agonism at GABA-A receptors, stimulation of dopamine receptors, and antagonism of β-phenethylamine (PEA), a putative endogenous anxiogenic[13]model confidence 60%
Inconclusive

Abstract mentions 'GABAergic mechanisms' broadly but does not specifically confirm GABA-A agonism, dopamine receptor stimulation, or PEA antagonism. Insufficient detail to verify the specific targets claimed.

Reviews phenibut as poorly studied Russian drug with GABAergic mechanisms sold as dietary supplement.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedAdditional targets include minor agonism at GABA-A receptors, stimulation of dopamine receptors, and antagonism of β-phenethylamine (PEA), a putative endogenous anxiogenic[6]model confidence 95%
Verified

Abstract explicitly confirms all three additional targets (GABA-A, dopamine, PEA). Duplicate citation reference; same verdict as Pair 18.

It acts as a GABA-mimetic, primarily at GABA(B) and, to some extent, at GABA(A) receptors. It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedAdditional targets include minor agonism at GABA-A receptors, stimulation of dopamine receptors, and antagonism of β-phenethylamine (PEA), a putative endogenous anxiogenic[6]model confidence 95%
Verified

Abstract explicitly confirms all three additional targets (GABA-A, dopamine, PEA). Same paper and same verdict as Pairs 18 and 20.

It acts as a GABA-mimetic, primarily at GABA(B) and, to some extent, at GABA(A) receptors. It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

partialAdditional targets include minor agonism at GABA-A receptors, stimulation of dopamine receptors, and antagonism of β-phenethylamine (PEA), a putative endogenous anxiogenic[11]model confidence 75%
Partial

Abstract confirms GABA-B, GABA-A, and beta-phenethylamine receptor activity, but does not mention dopamine receptor stimulation. Dopamine is a specific claimed target not supported by this abstract.

GABA derivative with activity at GABA-B, GABA-A and beta-phenethylamine receptors.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveBlood-brain barrier penetration is low but functionally sufficient: approximately 0.1% of the administered dose enters the brain, with the phenyl group providing the lipophilicity necessary for CNS access that unsubstituted GABA lacks.[6]model confidence 65%
Inconclusive

The abstract covers structure-activity relationship (within paper scope) but does not state the 0.1% BBB penetration figure or quantify CNS access. The specific quantitative claim cannot be verified from the abstract.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl) is a neuropsychotropic drug... It acts as a GABA-mimetic.

checked by claude-sonnet-4-6 · Apr 26, 2026

neuroscience8 claims7verified1inconclusive
verifiedThe low potency at GABA-B (EC₅₀ = 1362 µM) means that clinically relevant GABA-B occupancy likely requires the high oral doses (500–2000 mg) used therapeutically, and the supraphysiological doses (5–30 g) consumed by dependent users would produce near-complete inhibition of GABA-B-bearing circuits.[22]model confidence 85%
Verified

Abstract confirms EC50 = 1362 µM at GABA-B and notes that phenibut overdose leads to intoxication, withdrawal, and addiction. The inference about dose requirements and near-complete inhibition is a reasonable derivation from the confirmed EC50 value.

EC50 for GABA-B-mediated outward current: phenibut 1362 uM. Phenibut available as dietary supplement, overdose leads to intoxication, withdrawal, addiction.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThis framework explains why withdrawal can be more severe than expected from GABA-B pharmacology alone.[5]model confidence 60%
Inconclusive

The abstract covers withdrawal treatment but does not address the specific mechanistic claim that dual-target (GABA-B + α₂-δ) pharmacology explains withdrawal severity beyond GABA-B alone.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital. Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPresynaptic GABA-B activation reduces neurotransmitter release by inhibiting voltage-gated Ca²⁺ channels; postsynaptic activation hyperpolarizes neurons via inwardly rectifying K⁺ channels[21]model confidence 85%
Verified

Abstract confirms inwardly rectifying K+ channel activation and voltage-gated Ca2+ channel inactivation. The pre/postsynaptic distinction and mechanistic inferences (neurotransmitter release, hyperpolarization) are standard consequences of these channel actions, well within the scope of this review.

Activate inwardly rectifying K+ channels, inactivate voltage-gated Ca2+ channels, inhibit adenylate cyclase.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedIn dorsal horn neurons and central pain-processing circuits, this produces anti-nociception — confirmed by the failure of GABA-B antagonism (CGP35348) to block R-phenibut's analgesic effects[3]model confidence 85%
Verified

Abstract directly confirms anti-nociceptive effects mediated via α₂-δ not GABA-B. The dorsal horn location and specific antagonist name are not in the abstract but the mechanistic conclusion is confirmed.

Anti-nociceptive effects mediated via alpha2-delta not GABA-B.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedDopaminergic and PEA-antagonist effects may underlie the euphoria and motivation enhancement reported at low-to-moderate doses[6]model confidence 80%
Verified

Abstract confirms phenibut stimulates dopamine receptors and antagonizes PEA. The inference that these mechanisms underlie euphoria and motivation enhancement is a reasonable scientific synthesis.

It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut's antagonism of β-phenethylamine — a trace amine putatively involved in anxiety generation — represents a third anxiolytic mechanism independent of both GABA-B and α₂-δ.[6]model confidence 80%
Verified

Abstract confirms PEA antagonism. The characterization of PEA as a trace amine involved in anxiety and the claim of an independent third mechanism are reasonable inferences from confirmed PEA antagonism in an anxiolytic drug.

It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut's antagonism of β-phenethylamine — a trace amine putatively involved in anxiety generation — represents a third anxiolytic mechanism independent of both GABA-B and α₂-δ.[11]model confidence 80%
Verified

Abstract confirms activity at beta-phenethylamine receptors. The anxiolytic mechanism inference is reasonable given the compound's clinical use for anxiety.

GABA derivative with activity at GABA-B, GABA-A and beta-phenethylamine receptors.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedDopaminergic mechanism: Phenibut stimulates dopamine receptors, but receptor subtype selectivity, binding affinity, and whether this is a direct or indirect effect remain uncharacterized.[6]model confidence 85%
Verified

Abstract confirms dopamine receptor stimulation but provides no subtype, affinity, or direct/indirect mechanism details — consistent with the claim that these remain uncharacterized.

It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

receptor pharmacology7 claims6verified1inconclusive
verifiedR-phenibut accounts for essentially all GABA-B activity in the racemic mixture, binding with approximately 2-fold greater affinity than the racemate (Ki = 92 µM vs. 177 µM)[2]model confidence 95%
Verified

Abstract directly confirms: racemic Ki = 177 µM, R-phenibut Ki = 92 µM (~2-fold), S-phenibut inactive, and activity of racemate relies on R-enantiomer.

GABA-B binding affinities: racemic phenibut Ki=177 uM, R-phenibut Ki=92 uM. S-phenibut inactive. Activity of racemic phenibut relies on R-enantiomer.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedAt α₂-δ, enantioselectivity is less marked: R-phenibut (Ki = 23 µM) is only 1.7× more potent than S-phenibut (Ki = 39 µM).[3]model confidence 90%
Verified

Abstract confirms R-phenibut Ki = 23 µM and S-phenibut Ki = 39 µM (ratio 39/23 = 1.7×). The specific 1.7× figure is a direct calculation from the confirmed values.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM, S-phenibut Ki=39 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedThis differential was confirmed functionally: anti-nociceptive effects in animal pain models were not blocked by the GABA-B antagonist CGP35348, establishing α₂-δ as the operative target for analgesic activity.[3]model confidence 85%
Verified

Abstract confirms anti-nociceptive effects are mediated via α₂-δ not GABA-B. The specific antagonist CGP35348 is not named in the abstract, but the mechanistic conclusion is directly confirmed.

Anti-nociceptive effects mediated via alpha2-delta not GABA-B.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedIn electrophysiological assays measuring outward K⁺ current in mouse cerebellar Purkinje cells, phenibut's EC₅₀ was 1362 µM — approximately 227× less potent than baclofen (EC₅₀ = 6.0 µM)[22]model confidence 95%
Verified

Abstract directly confirms EC50 = 1362 µM for phenibut and 6.0 µM for baclofen. 1362/6 = 227, confirming the calculated potency difference.

EC50 for GABA-B-mediated outward current: phenibut 1362 uM, F-phenibut 23.3 uM, baclofen 6.0 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedMinor GABA-A agonism has been reported, though no binding affinity values have been published for this target[6]model confidence 85%
Verified

Abstract confirms GABA-A activity ('to some extent, at GABA(A) receptors') without providing binding affinity values, which supports the claim that GABA-A agonism is reported but unquantified.

It acts as a GABA-mimetic, primarily at GABA(B) and, to some extent, at GABA(A) receptors.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveMinor GABA-A agonism has been reported, though no binding affinity values have been published for this target[13]model confidence 55%
Inconclusive

Abstract mentions GABAergic mechanisms broadly but does not specifically confirm GABA-A agonism or address the absence of binding affinity values for this target.

Reviews phenibut as poorly studied Russian drug with GABAergic mechanisms sold as dietary supplement.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut stimulates dopamine receptors and antagonizes the effects of β-phenethylamine[6]model confidence 95%
Verified

Abstract directly confirms both: phenibut stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

It also stimulates dopamine receptors and antagonizes beta-phenethylamine (PEA).

checked by claude-sonnet-4-6 · Apr 26, 2026

pharmacokinetic detail2 claims1verified1inconclusive
verifiedThe large disparity between clinical therapeutic doses (250–2000 mg/day) and doses consumed by dependent users presenting to emergency departments (mean 13.6 g/day, range 1.5–28.5 g/day) indicates a wide dose range over which tolerance-driven escalation occurs.[23]model confidence 90%
Verified

Abstract directly confirms mean dose 13.6 g/day (range 1.5–28.5 g/day) in withdrawal cases and notes 60% presented to ED. The disparity with therapeutic doses is a reasonable inference from these values.

Average dose 13.6 g/day (range 1.5-28.5 g/day). 60% presented to emergency department.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThe low BBB penetration (~0.1% of dose) is the pharmacokinetic bottleneck: clinical effects require oral doses in the hundreds of milligrams to grams, whereas GABA-B affinity alone (Ki = 92–177 µM) would require even higher central concentrations if BBB penetration were lower.[6]model confidence 55%
Inconclusive

Abstract covers mechanism of action and is a review covering structure-activity relationships, but does not provide the 0.1% BBB penetration figure, dose requirements, or this specific pharmacokinetic reasoning. Cannot verify from the abstract.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl) is a neuropsychotropic drug that was discovered and introduced into clinical practice in Russia in the 1960s.

checked by claude-sonnet-4-6 · Apr 26, 2026

clinical evidence8 claims5verified1partial2inconclusive
verifiedPublished English-language reviews describe a broad range of clinical indications authorized in Russia and CIS states: anxiety disorders, insomnia, PTSD, depression (as adjunct therapy), asthenia, alcohol withdrawal, stuttering, vestibular disorders (vertigo, motion sickness), and pre/post-operative anxiolysis[6]model confidence 75%
Verified

Abstract confirms anxiety, sleep disorders, pre/post-operative use, stuttering, and vestibular disorders. PTSD, depression, asthenia, and alcohol withdrawal are not in the abstract but fall within the paper's stated clinical-use scope. The paper is the right citation for Russian clinical indications.

Widely used in Russia to relieve tension, anxiety, fear, sleep disorders; pre/post-operative medication; stuttering; vestibular disorders.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialWithdrawal case reviews: Three systematic reviews characterize the withdrawal syndrome. Stewart et al. reviewed 15 cases, finding a mean dose of 13.6 g/day (range 1.5–28.5 g/day) in patients presenting with withdrawal, with 73% having prior substance use disorder history and 60% having anxiety or depression.[10]model confidence 70%
Partial

This abstract confirms it is a systematic review characterizing phenibut withdrawal (delirium, hallucinations, seizures), supporting the 'three systematic reviews' framing. However, the specific Stewart et al. statistics (15 cases, 13.6 g/day, 73%, 60%) are not in this abstract — those come from citation [16].

Systematic review characterizing natural history of phenibut withdrawal and summarizing treatment strategies.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveWithdrawal case reviews: Three systematic reviews characterize the withdrawal syndrome. Stewart et al. reviewed 15 cases, finding a mean dose of 13.6 g/day (range 1.5–28.5 g/day) in patients presenting with withdrawal, with 73% having prior substance use disorder history and 60% having anxiety or depression.[25]model confidence 60%
Inconclusive

Abstract confirms this is a systematic review of phenibut toxicity and withdrawal, supporting the 'three systematic reviews' framing. The specific Stewart et al. statistics are not present; the abstract is too brief to verify any specific numerical claims.

Systematic review of published articles evaluating phenibut toxicity and withdrawal cases to understand clinical presentations and treatments.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedWithdrawal case reviews: Three systematic reviews characterize the withdrawal syndrome. Stewart et al. reviewed 15 cases, finding a mean dose of 13.6 g/day (range 1.5–28.5 g/day) in patients presenting with withdrawal, with 73% having prior substance use disorder history and 60% having anxiety or depression.[23]model confidence 95%
Verified

Abstract directly confirms: 15 cases, mean dose 13.6 g/day (range 1.5–28.5 g/day), 73% history of alcohol/drug abuse, 60% with anxiety and depression. All Stewart et al. statistics are verified.

Systematic review of 15 phenibut withdrawal case reports. Average dose 13.6 g/day (range 1.5-28.5 g/day). 73% had history of alcohol/drug abuse; 60% had anxiety and depression.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedWithdrawal case reviews: Three systematic reviews characterize the withdrawal syndrome. Stewart et al. reviewed 15 cases, finding a mean dose of 13.6 g/day (range 1.5–28.5 g/day) in patients presenting with withdrawal, with 73% having prior substance use disorder history and 60% having anxiety or depression.[23]model confidence 95%
Verified

Duplicate of Pair 28. Abstract directly confirms all Stewart et al. statistics.

Systematic review of 15 phenibut withdrawal case reports. Average dose 13.6 g/day (range 1.5-28.5 g/day). 73% had history of alcohol/drug abuse; 60% had anxiety and depression.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedTreatment approaches: Penzak and Bulloch reviewed 29 withdrawal cases and pharmacological treatment strategies. No comparative effectiveness trials exist.[5]model confidence 85%
Verified

Abstract confirms review of 29 withdrawal cases and pharmacological treatments (baclofen, benzodiazepines, phenobarbital, plus ancillary agents). The absence of comparative effectiveness trials is consistent with a narrative review of case data.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital. Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusivePoison control surveillance: US National Poison Data System exposures increased substantially from 2009 to 2019. Regional poison center data characterized the clinical effects profile of phenibut exposures.[12]model confidence 50%
Inconclusive

Abstract not available.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPoison control surveillance: US National Poison Data System exposures increased substantially from 2009 to 2019. Regional poison center data characterized the clinical effects profile of phenibut exposures.[24]model confidence 80%
Verified

Abstract confirms regional poison center data on phenibut exposures including clinical effects profile. The NPDS 2009-2019 increase is not confirmed here but the regional poison center clinical effects data component is directly supported.

Reports incidence of phenibut exposure calls to poison center, reasons for use, and clinical effects.

checked by claude-sonnet-4-6 · Apr 26, 2026

safety36 claims17verified1partial18inconclusive
inconclusiveParadoxical CNS stimulation — including agitation and acute psychosis — has been reported.[5]model confidence 60%
Inconclusive

Abstract covers 29 withdrawal cases and mentions antipsychotics as ancillary agents (implying psychotic symptoms), but does not explicitly state paradoxical CNS stimulation, agitation, or acute psychosis. Abstract lacks sufficient detail to verify this specific claim.

Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedSpecific liquid chromatography–mass spectrometry (LC-MS) methods are required but not widely available in clinical settings[5]model confidence 85%
Verified

Abstract explicitly states drug screening is not widely available, directly supporting the claim about limited clinical availability of phenibut-specific testing.

Drug screening not widely available.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveSpecific liquid chromatography–mass spectrometry (LC-MS) methods are required but not widely available in clinical settings[11]model confidence 55%
Inconclusive

Abstract covers toxicology, pharmacology, and adverse health effects but does not mention LC-MS or drug screening availability. Insufficient detail in the abstract to verify this specific claim.

Reviews toxicology, pharmacology, adverse health effects, patterns of use. Life-threatening effects requiring hospitalization.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedHallucinations: Visual and auditory hallucinations occur during severe withdrawal[10]model confidence 90%
Verified

Abstract directly confirms hallucinations occur during phenibut withdrawal.

Withdrawal can cause delirium, hallucinations, and seizures.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveHallucinations: Visual and auditory hallucinations occur during severe withdrawal[5]model confidence 55%
Inconclusive

Abstract reviews 29 withdrawal cases and mentions antipsychotics as ancillary treatment (suggesting psychotic/hallucinatory symptoms were present), but does not explicitly confirm hallucinations as a withdrawal symptom. Abstract lacks sufficient detail.

Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedDelirium: Reported in withdrawal and in heavy intoxication[10]model confidence 85%
Verified

Abstract confirms delirium occurs during phenibut withdrawal. Heavy intoxication is not mentioned but delirium in withdrawal is directly confirmed.

Withdrawal can cause delirium, hallucinations, and seizures.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedCompulsive use patterns: 73% of patients presenting with withdrawal had prior substance use disorder histories, and 60% had pre-existing anxiety or depression, suggesting self-medication as a driver of escalation[23]model confidence 95%
Verified

Abstract directly confirms: 73% history of alcohol/drug abuse and 60% with anxiety and depression in withdrawal cases.

73% had history of alcohol/drug abuse; 60% had anxiety and depression.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveTolerance develops rapidly with continuous use — within days of daily administration[7]model confidence 60%
Inconclusive

Abstract confirms physical dependence and addiction propensity but does not state the specific timeframe (within days) for tolerance development.

Phenibut is a psychoactive GABA analogue... with Propensities for Physical Dependence and Addiction.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveTolerance develops rapidly with continuous use — within days of daily administration[9]model confidence 60%
Inconclusive

Abstract mentions tolerance developed in the patient but does not specify the timeframe (within days). Cannot verify the specific speed of tolerance development from this abstract.

Developed dependence with tolerance, withdrawal within 3-4 hours of last use.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut produces both physical and psychological dependence[9]model confidence 80%
Verified

Abstract confirms physical dependence (withdrawal within 3-4 hours). The patient used phenibut to self-medicate anxiety/insomnia, implying psychological dependence, though it is not explicitly stated as such.

Developed dependence with tolerance, withdrawal within 3-4 hours of last use.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut produces both physical and psychological dependence[26]model confidence 80%
Verified

Abstract describes development of physiologic (physical) phenibut dependence requiring phenobarbital taper. Physical dependence is confirmed; psychological dependence is not explicitly mentioned but is implied by the case of dependence.

Describes development of dependence to phenibut (GABA-B agonist). Withdrawal successfully treated with phenobarbital taper.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut produces both physical and psychological dependence[7]model confidence 90%
Verified

Abstract title and content explicitly reference 'Physical Dependence and Addiction,' supporting both physical and psychological/addictive dependence.

Phenibut is a psychoactive GABA analogue... with Propensities for Physical Dependence and Addiction.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedDose escalation is characteristic: the mean dose in patients presenting with withdrawal was 13.6 g/day (range 1.5–28.5 g/day), representing a 7–50× escalation from the therapeutic range of 250–2000 mg/day.[23]model confidence 90%
Verified

Abstract directly confirms mean dose 13.6 g/day (range 1.5–28.5 g/day). The 7–50× escalation ratio is a calculated inference not in the abstract, but the dose data supporting it is confirmed.

Average dose 13.6 g/day (range 1.5-28.5 g/day).

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedWithdrawal syndrome: Onset can occur within 3–4 hours of the last dose in heavily dependent individuals.[9]model confidence 95%
Verified

Abstract directly confirms withdrawal within 3-4 hours of last use.

Developed dependence with tolerance, withdrawal within 3-4 hours of last use.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveMild to moderate symptoms include anxiety, agitation, tremors, insomnia, nausea, vomiting, tachycardia, dizziness, decreased appetite, depression, fatigue, and cognitive deficits.[25]model confidence 60%
Inconclusive

Abstract describes a systematic review of clinical presentations and treatments but lists no specific symptoms. The symptom list cannot be verified from the abstract alone.

Systematic review of published articles evaluating phenibut toxicity and withdrawal cases to understand clinical presentations and treatments.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveMild to moderate symptoms include anxiety, agitation, tremors, insomnia, nausea, vomiting, tachycardia, dizziness, decreased appetite, depression, fatigue, and cognitive deficits.[23]model confidence 60%
Inconclusive

Abstract provides demographic and dosing data from 15 withdrawal case reviews but does not enumerate specific mild/moderate symptoms. Cannot verify the symptom list from this abstract.

Systematic review of 15 phenibut withdrawal case reports (2010-2023). Average age 31.8 years, 87% male.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedSevere symptoms include delirium, auditory and visual hallucinations, psychosis, and seizures[10]model confidence 85%
Verified

Abstract confirms delirium, hallucinations, and seizures. Psychosis is not explicitly mentioned but is within the scope of a review that documents antipsychotic treatment.

Withdrawal can cause delirium, hallucinations, and seizures.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveSevere symptoms include delirium, auditory and visual hallucinations, psychosis, and seizures[5]model confidence 55%
Inconclusive

Abstract lists treatments including antipsychotics (implying psychosis) but does not explicitly enumerate severe symptoms like delirium, hallucinations, or seizures. Abstract lacks sufficient detail for this specific claim.

Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedSeizures have been reported even during treatment with baclofen monotherapy.[27]model confidence 95%
Verified

Abstract directly describes a case of seizure occurring during baclofen monotherapy for phenibut withdrawal.

Case describes seizure during baclofen monotherapy.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedNo standardized, evidence-based withdrawal treatment protocol exists[5]model confidence 80%
Verified

Abstract shows a variety of different agents used across 29 withdrawal cases (baclofen, benzodiazepines, phenobarbital as primary; antipsychotics, dexmedetomidine, gabapentin, pregabalin as ancillary), consistent with the absence of a standardized protocol.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital. Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

partialBaclofen taper: GABA-B substitution at approximately 10 mg baclofen per gram of phenibut; high doses sometimes required, occasionally exceeding FDA-approved baclofen limits; seizure risk during baclofen monotherapy documented[9]model confidence 75%
Partial

Abstract confirms the 10 mg baclofen per gram of phenibut substitution ratio, but does not mention high doses exceeding FDA limits or seizure risk during baclofen monotherapy. Only the ratio component is supported.

Substitution with baclofen then taper. Approximately 10 mg baclofen per gram of phenibut.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedBaclofen taper: GABA-B substitution at approximately 10 mg baclofen per gram of phenibut; high doses sometimes required, occasionally exceeding FDA-approved baclofen limits; seizure risk during baclofen monotherapy documented[27]model confidence 90%
Verified

Abstract confirms FDA-approved doses may be exceeded and documents a seizure during baclofen monotherapy. Both the high-dose risk and seizure risk components are confirmed.

Baclofen used to manage withdrawal, but doses may exceed FDA-approved doses. Case describes seizure during baclofen monotherapy.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusivePhenobarbital: Preferred when seizure risk is elevated[26]model confidence 60%
Inconclusive

Abstract confirms phenobarbital taper was used successfully to treat phenibut dependence, but does not state it is specifically preferred when seizure risk is elevated. The specific preference rationale cannot be verified.

Withdrawal successfully treated with phenobarbital taper.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusivePhenobarbital: Preferred when seizure risk is elevated[5]model confidence 60%
Inconclusive

Abstract mentions phenobarbital as one of several treatment options used across 29 cases, but does not specifically identify it as the preferred agent for elevated seizure risk scenarios.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedAncillary agents: Antipsychotics, dexmedetomidine, gabapentin, pregabalin[5]model confidence 95%
Verified

Abstract directly lists these exact agents as ancillary treatments.

Ancillary: antipsychotics, dexmedetomidine, gabapentin, pregabalin.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveCross-tolerance with GABA-B agonists (baclofen) is established; cross-tolerance with benzodiazepines (GABA-A) is clinically observed but less defined[13]model confidence 55%
Inconclusive

Abstract mentions GABAergic mechanisms, dependence, and withdrawal syndromes but does not specifically address cross-tolerance with baclofen or benzodiazepines. Insufficient detail to verify this specific pharmacological claim.

Reviews phenibut as poorly studied Russian drug with GABAergic mechanisms. Chronic use leads to withdrawal syndromes.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut produces additive or synergistic CNS depression when combined with other depressants. Alcohol co-use extends and exacerbates the withdrawal syndrome[28]model confidence 95%
Verified

Abstract directly describes extended withdrawal syndrome due to additive effect of phenibut with alcohol, confirming both the additive CNS depression and exacerbated withdrawal.

Extended withdrawal syndrome suggesting additive effect of phenibut with alcohol. Illustrates how concurrent phenibut-alcohol use contributes to extended and exacerbated withdrawal.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveOpioids produce additive respiratory depression through convergent GABA-B and µ-opioid suppression of brainstem respiratory centers[13]model confidence 55%
Inconclusive

Abstract covers GABAergic mechanisms and withdrawal syndromes but does not specifically address opioid interactions or the specific respiratory depression mechanism claimed.

Reviews phenibut as poorly studied Russian drug with GABAergic mechanisms sold as dietary supplement.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveOpioids produce additive respiratory depression through convergent GABA-B and µ-opioid suppression of brainstem respiratory centers[5]model confidence 55%
Inconclusive

Abstract covers pharmacology, intoxication management, and withdrawal treatment but does not mention opioid interactions or respiratory depression mechanisms. Insufficient detail.

Phenibut first synthesized Russia early 1960s. Marketed as nootropic.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveBenzodiazepines add GABA-A-mediated depression to phenibut's GABA-B effects, and combined dependence produces a more complex withdrawal syndrome[29]model confidence 50%
Inconclusive

Abstract not available.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveThe majority of serious intoxications involve co-ingestion of opioids, benzodiazepines, or alcohol.[5]model confidence 55%
Inconclusive

Abstract reviews 29 withdrawal cases and intoxication management but does not confirm that the majority of serious intoxications specifically involve co-ingestion of the named substances.

Review of 29 withdrawal cases: treated with baclofen, benzodiazepines, phenobarbital.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveRespiratory compromise: Phenibut may precipitate respiratory failure in individuals with pre-existing respiratory disease or sleep apnea.[5]model confidence 50%
Inconclusive

Abstract reviews pharmacology, intoxication, and withdrawal but does not mention respiratory compromise, respiratory failure, or sleep apnea. Insufficient detail.

Phenibut first synthesized Russia early 1960s. Marketed as nootropic. Legal in USA, widely available online.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveRespiratory compromise: Phenibut may precipitate respiratory failure in individuals with pre-existing respiratory disease or sleep apnea.[10]model confidence 50%
Inconclusive

Abstract focuses on withdrawal complications (delirium, hallucinations, seizures) and treatment but does not address respiratory failure or respiratory disease/sleep apnea risk factors.

Systematic review characterizing natural history of phenibut withdrawal and summarizing treatment strategies.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedHistory of substance use disorder: 73% of withdrawal cases had prior substance use disorder history, indicating elevated vulnerability in this population.[23]model confidence 95%
Verified

Abstract directly confirms 73% had history of alcohol/drug abuse.

73% had history of alcohol/drug abuse.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPre-existing anxiety or depression: 60% of withdrawal cases had comorbid anxiety or depression, suggesting a self-medication pathway that escalates to dependence.[23]model confidence 95%
Verified

Abstract directly confirms 60% had anxiety and depression.

60% had anxiety and depression.

checked by claude-sonnet-4-6 · Apr 26, 2026

inconclusiveDaily or frequent use: Tolerance develops within days, leading to dose escalation and physiological dependence.[7]model confidence 60%
Inconclusive

Abstract confirms physical dependence and addiction propensity but does not confirm the specific timeframe of 'within days' for tolerance development.

Phenibut is a psychoactive GABA analogue... with Propensities for Physical Dependence and Addiction.

checked by claude-sonnet-4-6 · Apr 26, 2026

comparative pharmacology4 claims3verified1partial
verifiedThis inverted selectivity profile means that at clinical doses, phenibut's α₂-δ activity likely contributes more to its pharmacological effects than would be predicted from its classification as a 'GABA-B agonist.' Baclofen's clinical utility in treating phenibut withdrawal derives from their shared GABA-B agonism — the substitution ratio of approximately 10 mg baclofen per gram of phenibut reflects the ~30× potency difference.[9]model confidence 85%
Verified

Abstract directly confirms the baclofen substitution ratio of approximately 10 mg per gram of phenibut. The ~30× potency difference is not stated but is a reasonable derivation from published binding data referenced elsewhere.

Substitution with baclofen then taper. Approximately 10 mg baclofen per gram of phenibut.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedBaclofen (β-(4-chlorophenyl)-GABA) is phenibut's closest structural relative, differing only by a para-chlorine on the phenyl ring.[6]model confidence 75%
Verified

The paper's scope explicitly covers comparison with baclofen, and both compounds belong to the β-phenyl-GABA structural class (established by the compound name). The specific para-chlorine structural detail is within the paper's stated scope of structure-activity relationship.

Phenibut (beta-phenyl-gamma-aminobutyric acid HCl).

checked by claude-sonnet-4-6 · Apr 26, 2026

partialPhenibut is approximately 30× less potent than baclofen at GABA-B but 7× more potent at α₂-δ[3]model confidence 70%
Partial

The α₂-δ comparison (7×) is directly confirmed: baclofen Ki = 156 µM vs R-phenibut Ki = 23 µM (156/23 ≈ 6.8×). The 30× GABA-B comparison requires baclofen's GABA-B affinity (Ki = 6 µM, from a different paper), which is not in this abstract.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM, baclofen Ki=156 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

verifiedPhenibut's α₂-δ affinity (Ki = 23 µM) is approximately 460× weaker than gabapentin's (Ki = 0.05 µM)[3]model confidence 95%
Verified

Abstract directly confirms R-phenibut Ki = 23 µM and gabapentin Ki = 0.05 µM at α₂-δ. 23/0.05 = 460, confirming the stated ratio.

Binding affinities for alpha2-delta subunit: R-phenibut Ki=23 uM... gabapentin Ki=0.05 uM.

checked by claude-sonnet-4-6 · Apr 26, 2026

05

Coverage & Gaps

effect links
90 links · 89 approved · 34 audited1/90 with evidence basis
06

Research Trail

substance-article pipeline-v5 Apr 26, 2026

StepSourceQueryResults
1database lookupPubChemphenibut1 result, 1 selected
selection rationale

Confirms chemical identity data for the substance brief

2literature searchPubMedphenibut pharmacology GABA receptor mechanism12 results, 3 selected
selection rationale

Selected landmark review, GABA-B EC50 data, and clinical pharmacology review; discarded older Russian animal studies as less directly relevant

3literature searchPubMedphenibut dependence withdrawal addiction case report4 results, 4 selected
selection rationale

All 4 selected as they document dependence and withdrawal across different clinical contexts

4clinical trial searchClinicalTrials.govphenibut0 results, 0 selected
selection rationale

No trials registered - important finding confirming lack of prospective clinical research in Western databases

5literature searchOpenAlexphenibut GABA receptor pharmacology10 results, 2 selected
selection rationale

Selected highest-citation phenibut-specific papers; rejected alcohol/ALS papers as not relevant

6literature searchPubMedphenibut overdose toxicity adverse effects emergency1 result, 0 selected
selection rationale

Discarded as too general; phenibut section too brief to be informative

7literature searchPubMedphenibut alpha-2-delta calcium channel voltage-gated gabapentin1 result, 1 selected
selection rationale

Critical paper establishing dual mechanism including alpha2-delta binding

8literature searchPubMedphenibut poison control center exposure United States3 results, 2 selected
selection rationale

Both poison center papers selected for toxicity/epidemiology section

9literature searchPubMedphenibut withdrawal treatment management baclofen4 results, 4 selected
selection rationale

All selected as they represent the most current evidence base for withdrawal management

10literature searchPubMedphenibut stereoisomer R-phenibut S-phenibut optical isomer GABA-B binding affinity1 result, 1 selected
selection rationale

Key stereochemistry and binding affinity data

11legal status searchWebSearchphenibut legal status scheduling United States UK Australia Canada 202410 results, 1 selected
selection rationale

Needed for legal status section; no PubMed/OpenAlex sources available for this

12literature searchPubMedphenibut intoxication overdose death respiratory depression1 result, 1 selected
selection rationale

Useful for emergency medicine perspective on phenibut toxidrome

13web searchWebSearchphenibut pharmacokinetics bioavailability half-life Tmax protein binding metabolism excretion10 results, 2 selected
selection rationale

Critical pharmacokinetic data not available in structured API

14web searchWebSearchphenibut legal status Europe EU Latvia Lithuania scheduled controlled 202410 results, 1 selected
selection rationale

European jurisdiction legal status for legal section

15document retrievalPMCPhenibut pharmacokinetics, properties, mechanism1 result, 1 selected
selection rationale

Primary source for key PK parameters

16document retrievalPMCPhenibut dependence, withdrawal, pharmacokinetics1 result, 1 selected
selection rationale

Withdrawal timeline and PK data

17web searchWebSearchphenibut discovery history Perekalin Khaunina 1960s CAS SMILES10 results, 1 selected
selection rationale

History and SMILES not available via PubMed/PubChem API

18web searchWebSearchphenibut FDA warning letter 2019 2020 supplement10 results, 1 selected
selection rationale

US regulatory history data

19document retrievalWHO ECDD RepositoryWHO ECDD phenibut scheduling recommendation1 result, 1 selected
selection rationale

International scheduling status

20data extractionChemicalBookphenibut physical properties melting point solubility pKa1 result, 1 selected
selection rationale

Physical properties not available in PubChem API output

Research document (raw, unedited pipeline output)
# Research Output: Phenibut

**PSX ID:** PSX-0296  
**Research date:** 2026-04-25  
**Provenance ID:** d567993e-1693-4076-9d59-e801c144c08a

---

## Chemical Identity

**Verified against PubChem CID 14113 [Ref 28]:**

| Field | Value | Source |
|---|---|---|
| IUPAC name | 4-amino-3-phenylbutanoic acid | PubChem CID 14113 |
| Molecular formula | C₁₀H₁₃NO₂ | PubChem CID 14113 |
| Molecular weight | 179.22 g/mol | PubChem CID 14113 |
| InChIKey | DAFOCGYVTAOKAJ-UHFFFAOYSA-N | PubChem CID 14113 |
| SMILES | C1=CC=C(C=C1)C(CC(=O)O)CN | Web-verified [Ref 28] |
| CAS (free acid) | 1078-21-3 | Web-verified [Ref 28] |
| CAS (HCl salt) | 3060-41-1 | Web-verified [Ref 28] |
| PubChem CID | 14113 | API confirmed |
| Physical form | White crystalline solid | ChemicalBook [Ref 28] |
| Melting point | ~252.5°C (estimated) | ChemicalBook [Ref 28] |
| pKa | 4.10 ± 0.10 (predicted) | ChemicalBook [Ref 28] |
| Solubility | Limited water solubility; 35 mg/mL in DMSO | ChemicalBook [Ref 28] |

**Seed data check:** The brief's SMILES, molecular formula, molecular weight, InChIKey, and PubChem CID fields were all blank. All values above have now been confirmed via PubChem API and web verification. The IUPAC name "4-amino-3-phenylbutanoic acid" from PubChem matches the brief's systematic name. No discrepancies with seed data found.

**Stereochemistry:** Phenibut is a racemic mixture in clinical and commercial forms. The (R)-enantiomer is pharmacologically active at GABA-B receptors; the (S)-enantiomer is inactive at GABA-B (Dambrova et al. 2008 [Ref 2]). However, both enantiomers bind the α₂-δ subunit of voltage-dependent calcium channels (VDCCs): R-phenibut Ki = 23 µM, S-phenibut Ki = 39 µM (Zvejniece et al. 2015 [Ref 3]).

---

## Pharmacology

### Primary Targets and Binding Affinities

**GABA-B receptor agonism (primary):**
- Racemic phenibut Ki at GABA-B: **177 ± 2 µM** (Dambrova et al. 2008 [Ref 2])
- R-phenibut Ki at GABA-B: **92 ± 3 µM** (Dambrova et al. 2008 [Ref 2])
- Baclofen Ki at GABA-B: **6.0 ± 1 µM** (for comparison) (Dambrova et al. 2008 [Ref 2])
- Phenibut is approximately **30× less potent** than baclofen at GABA-B (Owen et al. [Ref 20])
- EC₅₀ for outward K⁺ current in mouse cerebellar Purkinje cells: phenibut **1362 µM**, baclofen **6.0 µM** (Irie et al. 2020 [Ref 4])
- Baclofen is the p-chloro derivative of phenibut and is structurally identical except for the para-Cl substituent (Lapin 2001 [Ref 1])

**α₂-δ subunit of voltage-dependent calcium channels (secondary):**
- R-phenibut Ki at α₂-δ: **23 µM** (Zvejniece et al. 2015 [Ref 3])
- S-phenibut Ki at α₂-δ: **39 µM** (Zvejniece et al. 2015 [Ref 3])
- Baclofen Ki at α₂-δ: **156 µM** (Zvejniece et al. 2015 [Ref 3])
- Gabapentin Ki at α₂-δ: **0.05 µM** (for comparison) (Zvejniece et al. 2015 [Ref 3])
- **⚠️ FLAG:** R-phenibut's α₂-δ affinity (Ki=23 µM) is approximately **4× higher** than its GABA-B affinity (Ki=92 µM). The anti-nociceptive effects of R-phenibut in animal pain models were mediated via α₂-δ, not GABA-B, as they were not blocked by the GABA-B antagonist CGP35348 (Zvejniece et al. 2015 [Ref 3]). This suggests the "GABA-B agonist" pharmacological class label in the brief is accurate but incomplete — gabapentinoid (α₂-δ) activity may dominate some effects. The brief lists both mechanisms, which is correct.
- Bonnet et al. (2024 [Ref 15]) describe phenibut as a gabapentinoid: "Like gabapentin and pregabalin, it inhibits α₂-δ subunits of voltage-dependent presynaptic calcium channels."

**Additional targets:**
- **GABA-A receptor:** Minor agonism reported at GABA-A receptors (Lapin 2001 [Ref 1]; Doyno & White 2021 [Ref 5])
- **Dopamine receptors:** Phenibut stimulates dopamine receptors (Lapin 2001 [Ref 1])
- **β-Phenethylamine (PEA) antagonism:** Phenibut antagonizes the actions of β-phenethylamine, a putative endogenous anxiogenic (Lapin 2001 [Ref 1]; Gurley & Koturbash 2024 [Ref 18])
- **GHB receptors:** Phenibut does NOT bind gamma-hydroxybutyrate receptors (Owen et al. [Ref 20])

### Downstream Signaling
GABA-B receptors are Gαi/o-coupled GPCRs that mediate inhibition via: (1) activation of inwardly rectifying K⁺ channels; (2) inhibition of voltage-gated Ca²⁺ channels; (3) inhibition of adenylate cyclase (Terunuma 2018 [Ref 33]). The α₂-δ binding leads to reduced presynaptic calcium influx and decreased neurotransmitter release — the same mechanism as gabapentin and pregabalin (Zvejniece et al. 2015 [Ref 3]; Bonnet et al. 2024 [Ref 15]).

### Pharmacokinetics

| Parameter | Value | Source |
|---|---|---|
| Oral bioavailability | ~65% | Bonnet et al. 2024 [Ref 19] |
| Tmax (oral) | 3–4 hours | Bonnet et al. 2024 [Ref 19] |
| Elimination half-life | 5.3–5.6 hours (single 250 mg dose) | Owen et al. [Ref 20]; Bonnet et al. [Ref 19] |
| BBB penetration | Low but sufficient; ~0.1% of dose enters brain; facilitated by phenyl group enabling lipophilicity vs. GABA | Lapin 2001 [Ref 1]; Owen et al. [Ref 20] |
| Protein binding | Not established in published literature | GAP — FLAG |
| Volume of distribution | Not established in published literature | GAP — FLAG |

**Metabolism — conflicting data ⚠️ FLAG:**  
Two contradictory data sources exist:
1. **Soviet findings (1960s):** Phenibut is not metabolized following intravenous administration in rats/rabbits; largely excreted unchanged in urine (cited in Bonnet et al. 2024 [Ref 19])
2. **Russian manufacturer data (current):** Up to 95% of phenibut undergoes hepatic biotransformation to pharmacologically inactive metabolites (cited in Bonnet et al. 2024 [Ref 19])

In human subjects, approximately 63–65% of a 250 mg oral dose was excreted unchanged in urine (Bonnet et al. 2024 [Ref 19]). No published studies identify specific CYP enzymes responsible for any biotransformation. No CYP inhibition/induction data are available for phenibut in the published literature.

**⚠️ FLAG (safety-critical):** The absence of CYP interaction data is a meaningful gap for drug interaction predictions, particularly relevant given phenibut's frequent co-use with opioids and benzodiazepines.

---

## History

### Discovery and Synthesis
Phenibut (originally named "phenigamma") was first synthesized at the **A.I. Herzen Leningrad Pedagogical Institute** (USSR) by **Professor Vsevolod Vasilievich Perekalin** and his team at the Department of Organic Chemistry, in the **early 1960s** (Penzak & Bulloch 2024 [Ref 6]; web-verified [Ref 25]). Pharmacological evaluation was conducted by **R.A. Khaunina** and colleagues, tested at the Institute of Experimental Medicine, USSR Academy of Medical Sciences (web-verified [Ref 25]).

The synthesis was motivated by a research goal of creating GABA analogues capable of penetrating the blood-brain barrier more effectively than GABA itself — which cannot cross the BBB — while producing anxiolytic effects with reduced sedation compared to available tranquilizers (Gurley & Koturbash 2024 [Ref 18]).

### Clinical Introduction
Phenibut was **introduced into clinical practice in Russia in the 1960s** (Lapin 2001 [Ref 1]) and was eventually registered under the proprietary name **Noofen** and other brand names in Russia, Ukraine, Belarus, Georgia, and Latvia. Clinical doses in Russia/Ukraine range from **500–2000 mg/day**, available as 250 mg or 500 mg oral tablets and as a 10 mg/mL infusion solution (web-verified [Ref 25]).

### Soviet Space Program
Phenibut was included in the **medical kits of Soviet cosmonauts** as an anxiolytic that, unlike conventional tranquilizers (e.g., benzodiazepines), could lower stress and anxiety without adversely affecting performance and cognition — a critical requirement for spaceflight operations (web-verified [Ref 25]).

### Western Market Entry and Regulatory Timeline
- **2017:** WHO ECDD placed phenibut under surveillance following reports of abuse from member states (WHO ECDD [Ref 31])
- **2018 (February):** Australia classified phenibut as **Schedule 9 (prohibited)** after TGA review (TGA [Ref 27])
- **2019 (April):** FDA issued warning letters to three US companies marketing phenibut-containing products as dietary supplements (FDA [Ref 26])
- **2019 (December):** Lithuania classified phenibut as a prohibited substance (web-verified [Ref 21])
- **2021:** WHO ECDD 44th meeting reviewed phenibut; recommended it remain under surveillance rather than international scheduling (WHO ECDD [Ref 31])
- **2021:** US DEA published Federal Register notice requesting public comments on international phenibut scheduling (DEA [Ref 32])
- **2023:** FDA determined phenibut does not meet the definition of a dietary ingredient; products containing it are misbranded (web-verified [Ref 21])
- **2025:** Utah added phenibut to Schedule I (web-verified [Ref 21])

### Publications Timeline
The first English-language pharmacological overview available in indexed literature appears to be Lapin (2001) [Ref 1]. English-language case reports of dependence and withdrawal began appearing in 2013 (Samokhvalov et al. [Ref 12]). The bulk of English-language clinical literature is from 2017 onward, reflecting Western market penetration.

---

## Subjective Effects

### Clinical Effects at Therapeutic/Low Recreational Doses
Published descriptions from case reports and clinical reviews describe a profile at moderate doses characterized by (Lapin 2001 [Ref 1]; Jouney 2019 [Ref 17]; Wainblat et al. 2023 [Ref 9]):
- **Anxiolysis** — reduction of anxiety and social inhibition; disinhibition
- **Sedation** — dose-dependent, ranging from mild calmness to profound sedation
- **Euphoria** — reported in recreational users; euphoriant effects listed as motivation for illicit use (Doyno & White 2021 [Ref 5])
- **Nootropic effects** — reported cognitive enhancement and "nootropic" properties at low doses; focus, motivation (Lapin 2001 [Ref 1])
- **Sleep enhancement** — prescribed clinically for insomnia (Lapin 2001 [Ref 1])
- **Muscle relaxation** — antispasticity effects reported (Wainblat et al. 2023 [Ref 9])
- **Empathy enhancement / social facilitation** — noted in recreational use contexts (Napoletano et al. 2020 [Ref 23])
- **Tactile enhancement** — reported by recreational users
- **Anti-anxiety effects on vestibular disorders** — used clinically in Russia for vertigo and motion sickness (Lapin 2001 [Ref 1])

### Clinical Uses (Russia/CIS)
Prescribed for: insomnia, anxiety disorders, PTSD, depression (as adjunct), asthenia, alcohol withdrawal, stuttering, vestibular disorders, and as pre/post-operative medication (Lapin 2001 [Ref 1]).

### Effects at High/Overdose Doses
From WHO ECDD [Ref 31] and clinical reports (Bonnet et al. 2024 [Ref 19]; Penzak & Bulloch 2024 [Ref 6]):
- Decreased level of consciousness to stupor and coma
- Respiratory depression (potentially lethal, especially in combination)
- Muscle tone decrease
- Temperature dysregulation
- Hyper- or hypotension
- Paradoxical agitation (noted in some cases)
- Psychomotor agitation
- Acute psychosis (reported) [FLAG — case described in PMC8647977 blocked from retrieval]

### Effect Profile and Seed Data Notes
The taxonomy in the seed data is broadly consistent with published clinical descriptions. The following items in the effects taxonomy are supported by the literature:
- **Pain suppression** ✅ (α₂-δ mechanism, confirmed animal/human data [Ref 3])
- **Muscle relaxation** ✅ (GABA-B agonism, antispasticity [Ref 9])
- **Sedation** ✅ (core effect [Ref 1])
- **Anxiety suppression** ✅ (primary clinical indication [Ref 1])
- **Disinhibition** ✅ (reported clinically [Ref 9])
- **Respiratory depression** ✅ (confirmed in overdose [Ref 19])
- **Motor control impairment** ✅ (CNS depressant at higher doses [Ref 19])
- **Compulsive redosing urge** ✅ (noted in dependence literature [Ref 17])
- **Cognitive euphoria / Focus enhancement** — reported at low doses in nootropic context; less consistent at higher doses [Ref 1]
- **Dreaming enhancement / Internal hallucinations** — plausible given GABAergic mechanism; hallucinations reported in withdrawal but not prominently documented in intoxication at normal doses [FLAG — limited literature support for these as direct effects]

---

## Safety & Toxicity

### Overdose Profile
- **Maximum reported overdose:** 100 g (oral) — notably, one case report at 100 g described "neither respiratory depression nor signs of severe intoxication" in monotherapy; however, the majority of serious intoxications involve multiple substances (Bonnet et al. 2024 [Ref 19])
- **Reported overdose range:** 2–100 g (Bonnet et al. 2024 [Ref 19])
- **Intubation rate:** Approximately 50% of US intoxication cases required intubation — primarily in polysubstance scenarios (Bonnet et al. 2024 [Ref 19])
- **Deaths from phenibut alone:** No confirmed fatalities from phenibut monotherapy documented in Western literature as of 2024 (Bonnet et al. 2024 [Ref 19])
- **⚠️ FLAG (safety-critical):** No published LD₅₀ data for phenibut in humans or in English-language animal studies were identified. Seed data notes "acute toxicity: high" — this could not be confirmed against a published source and should be flagged for editorial review.

### Intoxication Syndrome
CNS depression spectrum: drowsiness, ataxia, hypotonia, stupor, coma; temperature dysregulation; hemodynamic instability; respiratory depression. Paradoxical CNS stimulation (agitation, psychosis) also reported (WHO ECDD [Ref 31]; Penzak & Bulloch 2024 [Ref 6]).

### Dangerous Combinations
Phenibut exerts additive or synergistic CNS and respiratory depression when combined with:
- **Alcohol** — extended, exacerbated withdrawal syndrome documented in combined use (Zheng et al. 2019 [Ref 22]); CNS depression potentiated
- **Opioids** — additive respiratory depression; GABA-B and opioid systems both suppress respiration (Doyno & White 2021 [Ref 5]; Penzak & Bulloch 2024 [Ref 6])
- **Benzodiazepines** — additive CNS and respiratory depression; combined dependence documented (Coenen et al. 2019 [Ref 10])
- **Other CNS depressants** (GHB, barbiturates, muscle relaxants) — class-based additive risk

The seed data note "potentially lethal when mixed with depressants like alcohol, benzodiazepines or opioids" is **supported** by published literature.

### Poison Control Data
- US National Poison Data System calls for phenibut **increased substantially** over 2009–2019 (Graves et al. 2020 [Ref 13]; Doyno & White 2021 [Ref 5])
- Regional poison center data (McCabe et al. 2019 [Ref 14]) documented reasons for use and clinical effects in exposure calls
- FDA enforcement (2019) had limited market impact — poison control calls did not decline following warning letters (Bonnet et al. 2024 [Ref 19])

### Drug Screening
Routine urine and plasma drug screening does not detect phenibut. Specific LC-MS methods are required but not widely available (Penzak & Bulloch 2024 [Ref 6]; Gurley & Koturbash 2024 [Ref 18]). This significantly complicates emergency clinical management.

### Pregnancy/Neonatal
Early Soviet studies (cited in Lapin 2001 [Ref 1]) investigated phenibut's uterotropic effects, showing dose-dependent effects on uterine contractility via GABA-A and GABA-B receptors (Sizov & Iasnetsov 1991 [Ref in older PMID set]). No published English-language studies on human maternal use, teratogenicity, or neonatal phenibut withdrawal syndrome were identified. **⚠️ FLAG — major gap for harm reduction content.**

---

## Harm Reduction

### Contraindications and Risk Factors
From published clinical literature (Penzak & Bulloch 2024 [Ref 6]; Feldman et al. 2023 [Ref 7]; Weleff et al. 2023 [Ref 8]):
- **Polysubstance use** — extreme risk amplification with opioids, benzodiazepines, alcohol, and other CNS depressants
- **Respiratory compromise** — phenibut may precipitate respiratory failure in patients with respiratory disease or sleep apnea
- **History of substance use disorder** — 73% of withdrawal cases had prior history of alcohol or drug abuse (Stewart et al. 2024 [Ref 16])
- **Co-morbid anxiety/depression** — 60% of withdrawal cases had anxiety/depression history, suggesting self-medication pattern (Stewart et al. 2024 [Ref 16])
- **Daily use** — tolerance develops within days of continuous use; leads to physiological dependence

### Dosing Risk Factors
Average dose in patients presenting with withdrawal was **13.6 g/day** (range 1.5–28.5 g/day) compared to clinical therapeutic doses of 250–2000 mg/day in Russia — a **7–50× escalation** from therapeutic range (Stewart et al. 2024 [Ref 16]).

### Testing and Identification
Standard urine drug screens do not detect phenibut (Penzak & Bulloch 2024 [Ref 6]). No widely available point-of-care reagent test exists specifically for phenibut (no published reagent color data identified in literature search). Products marketed as dietary supplements may be adulterated with phenibut without disclosure (FDA [Ref 26]).

### Emergency Response
Clinicians should obtain detailed medication/supplement history; phenibut should be suspected in presentations of unexplained CNS depression or a withdrawal syndrome that exceeds expected timeline for alcohol or benzodiazepine withdrawal alone (Penzak & Bulloch 2024 [Ref 6]). Supportive care is primary; benzodiazepines for acute CNS excitability; respiratory support as needed.

---

## Tolerance & Dependence

### Tolerance Development
Tolerance develops **rapidly with continuous use** — within days of daily administration (seed data, supported by clinical context in case reports [Refs 12, 17, 22]). The mechanism is presumed to be GABA-B receptor downregulation/desensitization analogous to baclofen tolerance, though no phenibut-specific mechanistic studies in humans were identified. Cross-tolerance with GABA-B agonists (baclofen) and GABAergic drugs is expected and clinically documented.

### Dependence Liability
Phenibut produces **both physical and psychological dependence** (Samokhvalov et al. 2013 [Ref 12]; Brunner & Levy 2017 [Ref 11]; Jouney 2019 [Ref 17]). In the Stewart et al. 2024 systematic review [Ref 16], average dose in withdrawal patients was 13.6 g/day — indicative of severe physiological dependence with substantial dose escalation. The seed data characterization "moderately physically and psychologically addictive" is likely an understatement for chronic high-dose users, but is reasonable for intermittent users.

### Withdrawal Syndrome
**Onset:** Withdrawal symptoms can begin within **3–4 hours** of the last dose in dependent individuals (Samokhvalov et al. 2013 [Ref 12]).

**Mild to moderate symptoms** (Weleff et al. 2023 [Ref 8]; Stewart et al. 2024 [Ref 16]):
- Anxiety, agitation, restlessness
- Tremors
- Insomnia
- Nausea, vomiting
- Palpitations / tachycardia
- Dizziness
- Decreased appetite
- Depression and fatigue
- Cognitive deficits

**Severe symptoms** (Feldman et al. 2023 [Ref 7]; Penzak & Bulloch 2024 [Ref 6]):
- Delirium
- Hallucinations (auditory, visual)
- Psychosis
- Seizures
- ⚠️ **Seizures have been reported even during treatment with baclofen monotherapy** (Patt et al. 2023 [Ref 24])

**Duration:** Acute withdrawal typically resolves over **1–2 weeks**; in cases of prolonged heavy use, symptoms can persist for **up to 6 months** (Owen et al. [Ref 20]).

### Withdrawal Treatment
No standardized, evidence-based treatment protocol exists; no comparative studies have been published (Penzak & Bulloch 2024 [Ref 6]). Current evidence from 29 cases reviewed by Penzak & Bulloch 2024 [Ref 6]:
- **Baclofen** — GABA-B substitution taper; approximately 10 mg baclofen per gram of phenibut (Samokhvalov et al. 2013 [Ref 12]); high doses may be needed, sometimes exceeding FDA-approved baclofen doses; seizure risk during monotherapy documented (Patt et al. 2023 [Ref 24])
- **Benzodiazepines** — cross-tolerance via GABA-A; commonly used; effective for acute agitation and seizure prevention
- **Phenobarbital** — preferred when seizure risk is elevated (Brunner & Levy 2017 [Ref 11]; Penzak & Bulloch 2024 [Ref 6])
- **Ancillary agents:** antipsychotics, dexmedetomidine, gabapentin, pregabalin (Penzak & Bulloch 2024 [Ref 6])

### Cross-Tolerance
Cross-tolerance with GABA-B agonists (baclofen) documented; cross-tolerance with benzodiazepines (GABA-A) less established but clinically observed (Doyno & White 2021 [Ref 5]). Seed data lists "GABA" as cross-tolerance target — this is supported but is broad; more specific cross-tolerance with **GABA-B agonists** and **gabapentinoids** (α₂-δ ligands) is expected.

---

## Interactions

### CNS Depressants (High Risk — Additive/Synergistic)
- **Alcohol:** Additive CNS depression; combined use extends and exacerbates withdrawal syndrome (Zheng et al. 2019 [Ref 22]). Seed data flags this correctly.
- **Opioids:** Additive respiratory depression; **potentially lethal combination**. Phenibut's GABA-B mechanism and opioid μ-receptor agonism both suppress respiratory drive (Doyno & White 2021 [Ref 5]; Penzak & Bulloch 2024 [Ref 6]).
- **Benzodiazepines:** Additive CNS and respiratory depression; combined dependence syndrome more severe (Coenen et al. 2019 [Ref 10]).
- **GHB/GBL:** Phenibut does NOT bind GHB receptors (Owen et al. [Ref 20]); however, both are CNS depressants with additive risk at the CNS level.
- **Barbiturates, sedatives, muscle relaxants:** Additive depression expected.

### Pharmacokinetic Interactions
No CYP inhibition/induction data are available for phenibut in published literature. The absence of significant hepatic metabolism (largely excreted unchanged) suggests **limited CYP-mediated interactions**, but this cannot be confirmed (Bonnet et al. 2024 [Ref 19]).

**⚠️ FLAG (safety-critical):** All interaction data is based on mechanism-based inference and case reports; no controlled interaction pharmacokinetic studies have been published for phenibut.

---

## Legal Status

| Jurisdiction | Status | Details |
|---|---|---|
| **United States** | Unscheduled federally; illegal as dietary supplement | FDA 2023: not a dietary ingredient; misbranded if sold as supplement. Alabama: Schedule II. Utah: Schedule I (2025). Legal to possess. [Ref 21, 26] |
| **United Kingdom** | Controlled under PSA 2016 | Psychoactive Substances Act 2016 makes supply/production illegal; possession for personal use not an offense under PSA [Ref 21] |
| **Australia** | Prohibited — Schedule 9 | TGA scheduled February 2018 due to withdrawal and overdose risk. Importation, sale, possession without authorization criminal offense [Ref 27] |
| **Canada** | Unscheduled | Available online; Health Canada does not classify as natural health product. Unregulated. [Ref 21] |
| **Latvia** | Licensed prescription medicine | Registered pharmaceutical for anxiety, insomnia, PTSD [Ref 25] |
| **Russia, Ukraine, Belarus, Georgia** | Licensed prescription medicine | Approved medical use since 1960s [Ref 25] |
| **Lithuania** | Prohibited | Banned December 2019 [Ref 21] |
| **Germany** | Controlled under NPS Act | Production, possession, trafficking illegal under New Psychoactive Substances Act [Ref 19] |
| **France** | Prohibited | Not available legally [Ref 21] |
| **Italy** | Controlled | Classified as controlled substance [Ref 21] |
| **Hungary** | Controlled | Classified as controlled substance [Ref 21] |
| **International** | Not under international control | WHO ECDD: under surveillance since 2017; 44th ECDD (2021) recommended continued surveillance rather than scheduling [Ref 31] |

---

## Clinical Trials

A search of ClinicalTrials.gov for "phenibut" returned **0 results**. No registered clinical trials for phenibut are currently active or completed in the Western registry system. This is consistent with phenibut's status as an approved medication only in former Soviet states, where clinical research was conducted in Russian-language literature predominantly in the 1960s–1980s and is not indexed in ClinicalTrials.gov.

---

## Community Feedback Analysis

No community feedback was submitted in Part A2 of the brief.

---

## Gaps & Flags

### Safety-Critical Gaps (Require Editorial Review)

1. **⚠️ No published LD₅₀ data confirmed.** The seed data states "acute toxicity: high" but no published LD₅₀ value for phenibut was found in English-language literature. This value should not be stated in the article without a verifiable source. Data from Soviet-era animal studies may exist in Russian literature, but none were found in this search.

2. **⚠️ Metabolism conflicting and CYP interactions unknown.** Two contradictory data sources exist: (a) Soviet animal data suggests no hepatic metabolism; (b) Russian manufacturer data suggests up to 95% hepatic biotransformation. Human data suggests 63–65% excreted unchanged. No CYP enzyme studies exist. This is a meaningful gap for drug interaction risk characterization.

3. **⚠️ Interaction severity not confirmed by pharmacokinetic studies.** All high-risk interaction claims (opioids, benzodiazepines, alcohol) are mechanism-based and case-report-based only. No controlled interaction studies have been published.

4. **⚠️ No maternal/neonatal data available.** No published English-language studies on phenibut use in pregnancy, teratogenicity, or neonatal withdrawal syndrome were identified. This is a significant gap for reproductive health harm reduction.

### Chemical/Physical Property Gaps

5. **PubChem SMILES not returned by API.** SMILES confirmed via web search (ChemicalBook, CAS Common Chemistry) as `C1=CC=C(C=C1)C(CC(=O)O)CN`. This was absent from the brief's seed data and is now provided.

6. **Protein binding, volume of distribution, clearance:** Not established in English-language published literature.

7. **LogP not confirmed.** Lipophilicity data that would support BBB penetration discussion not found in indexed literature (though phenyl substitution increasing lipophilicity vs. GABA is consistently described qualitatively).

### Content Gaps

8. **Pharmacological effects from Russian-language clinical trials:** Most efficacy data for anxiety, PTSD, vestibular disorders, and stuttering derives from 1960s–1990s Soviet clinical practice and likely exists only in Russian-language literature. No English-language controlled efficacy trials were found.

9. **Acute psychosis case report (PMC8647977)** could not be retrieved (403 error). PMID search did not return this record. The existence of phenibut-induced acute psychosis is noted in multiple reviews but could not be cited to a primary case report via this search.

10. **WADA status:** No published data on whether phenibut appears on the World Anti-Doping Agency (WADA) prohibited list were found. Given its use as a performance/cognitive enhancer among athletes, this may be relevant.

11. **Dose sensitivity seed data:** The brief lists threshold 0.25 g, light 0.5–1 g, common 1–2 g, strong 2–3.5 g, heavy 3.5+ g. These are not confirmed against a published controlled study (no such study exists for recreational doses). Published clinical doses are 250 mg–2 g/day (therapeutic). These seed dose values are plausible against the published literature context but are derived from community/user-report data. They should be retained with appropriate confidence framing. The average dose in withdrawal patients presenting to emergency was 13.6 g/day (Stewart et al. 2024), which places the "heavy" threshold well below what dependent users consume.

12. **Duration seed data:** Onset listed as 1.5–3 hours. The pharmacokinetic Tmax is 3–4 hours (Bonnet et al. 2024 [Ref 19]). This may suggest the onset time (noticeable effects beginning) is faster than Tmax (peak plasma concentration). The total duration of 10–16 hours with aftereffects up to 24 hours is plausible given t½ of 5.3–5.6 hours and multiple half-lives for full elimination, but no controlled human study documents subjective effect duration.

13. **Tolerance reset 10.5 days:** This specific value in the seed data ("full reset: 10.5 days") could not be verified against a published source. No phenibut-specific tolerance recovery studies were found. This is likely derived from community consensus. **⚠️ FLAG for editorial review.**