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Psychedex
Sources
42
6 strong · 28 moderate · 8 weak

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

Claims checked
88
67verified21inconclusive

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

Generated
Apr 28, 2026 · pipeline-v5
Values approved
90/90 (100%)

Data points an editor reviewed and accepted for publication.

01

Value Provenance

Dosing

oraltrace

FieldPublishedAI ProposedConfidence
Threshold200 mg200 mgmedium
Low200–900 mg200–900 mgmedium
Common900–1500 mg900–1500 mgmedium
Strong1500–2400 mg1500–2400 mgmedium
Heavy2400+ mg2400+ mgmedium
Editorial

Dose tiers from existing Psychedex database (community-curated pharmacological data). Threshold 200 mg, light 200–900 mg, common 900–1,500 mg, strong 1,500–2,400 mg, heavy 2,400+ mg. These are consistent with clinical therapeutic dose range (300–3,600 mg/day) and recreational dose reports in qualitative misuse literature. No published controlled study provides recreational dose-response thresholds specifically. Bioavailability range 33–69% reflects dose-dependent saturable absorption from Bockbrader et al. 2010 and Tran et al. 2017.

Reasoning

Dose tiers from existing Psychedex database (community-curated pharmacological data). Threshold 200 mg, light 200–900 mg, common 900–1,500 mg, strong 1,500–2,400 mg, heavy 2,400+ mg. These are consistent with clinical therapeutic dose range (300–3,600 mg/day) and recreational dose reports in qualitative misuse literature. No published controlled study provides recreational dose-response thresholds specifically. Bioavailability range 33–69% reflects dose-dependent saturable absorption from Bockbrader et al. 2010 and Tran et al. 2017.

Evidence basis: community_consensus_large

Duration

oral

FieldPublishedAI ProposedConfidence
Onsettrace30–120 minutes30–120 minutesmedium
Editorial

Onset 30–120 min from existing database. Lower bound (30 min) is plausible but not confirmed by published PK studies; Tmax of 3–4 hours (Bockbrader et al. 2010) suggests first perceptible effects begin well before peak plasma concentration.

Reasoning

Onset 30–120 min from existing database. Lower bound (30 min) is plausible but not confirmed by published PK studies; Tmax of 3–4 hours (Bockbrader et al. 2010) suggests first perceptible effects begin well before peak plasma concentration.

Evidence basis: community_consensus_large

Come uptrace45–90 minutes45–90 minutesmedium
Editorial

Come-up duration inferred from the gap between onset (30–120 min) and peak effects aligned with Tmax (3–4 hours). Community reports consistent with 45–90 min buildup phase.

Reasoning

Come-up duration inferred from the gap between onset (30–120 min) and peak effects aligned with Tmax (3–4 hours). Community reports consistent with 45–90 min buildup phase.

Evidence basis: community_consensus_large

Peaktrace1.5–3 hours1.5–3 hoursmedium
Editorial

Peak duration of 120–180 min from existing database. Consistent with Tmax 3–4 hours and half-life 5–7 hours — peak intensity window spans roughly 2–5 hours post-ingestion.

Reasoning

Peak duration of 120–180 min from existing database. Consistent with Tmax 3–4 hours and half-life 5–7 hours — peak intensity window spans roughly 2–5 hours post-ingestion.

Evidence basis: community_consensus_large

Offsettrace2–4 hours2–4 hoursmedium
Editorial

Offset inferred from half-life of 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995) and total subjective duration of 6–10 hours. The decline from peak to baseline spans approximately 2–4 hours.

Reasoning

Offset inferred from half-life of 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995) and total subjective duration of 6–10 hours. The decline from peak to baseline spans approximately 2–4 hours.

Evidence basis: community_consensus_large

Totaltrace6–10 hours6–10 hoursmedium
Editorial

Total subjective duration 6–10 hours from existing database. Consistent with elimination half-life of 5–7 hours — subjective effects resolve over approximately 1–1.5 half-lives after peak.

Reasoning

Total subjective duration 6–10 hours from existing database. Consistent with elimination half-life of 5–7 hours — subjective effects resolve over approximately 1–1.5 half-lives after peak.

Evidence basis: community_consensus_large

After effectstrace2–8 hours2–8 hourslow
Editorial

Residual sedation and drowsiness may persist beyond the subjective experience window, particularly at higher doses or in elderly/renal-impaired populations. Duration estimated from clinical adverse event reports of next-day somnolence. Not precisely characterized in published literature.

Reasoning

Residual sedation and drowsiness may persist beyond the subjective experience window, particularly at higher doses or in elderly/renal-impaired populations. Duration estimated from clinical adverse event reports of next-day somnolence. Not precisely characterized in published literature.

Evidence basis: community_consensus_small

Safety

Toxicity Profiletrace

FieldPublishedAI ProposedConfidence
Acutelowlowhigh
Chroniclowlowhigh
Organs Affectedcentral nervous systemcentral nervous systemhigh
Editorial

Classified as low acute toxicity based on: no LD50 established at 8,000 mg/kg (FDA label), only one documented sole-gabapentin fatality at extreme concentrations (Middleton 2011), and reversible overdose symptoms. Low chronic toxicity based on: no carcinogenicity in 2-year studies, no organ damage at therapeutic doses, and 30+ years of extensive clinical use. Principal risk is pharmacodynamic interaction with opioids, not intrinsic toxicity.

Reasoning

Classified as low acute toxicity based on: no LD50 established at 8,000 mg/kg (FDA label), only one documented sole-gabapentin fatality at extreme concentrations (Middleton 2011), and reversible overdose symptoms. Low chronic toxicity based on: no carcinogenicity in 2-year studies, no organ damage at therapeutic doses, and 30+ years of extensive clinical use. Principal risk is pharmacodynamic interaction with opioids, not intrinsic toxicity.

Evidence basis: systematic_review

Dependence Profiletrace

FieldPublishedAI ProposedConfidence
Physicalmoderatemoderatehigh
Psychologicallowlowhigh
Compulsive Redosinglowlowhigh
Dose Escalationmoderatemoderatehigh
Editorial

Physical dependence well-documented across multiple case reports and reviews (Norton 2001, Mersfelder & Nichols 2016, Deng et al. 2021). Behavioral dependence liability very low in general population per Bonnet et al. 2018 (0 gabapentin-specific cases without SUD history). Elevated risk in OUD populations per Bastiaens et al. 2016 (26% vs 4%). Dose escalation tendency moderate due to tolerance development and saturable absorption encouraging higher doses.

Reasoning

Physical dependence well-documented across multiple case reports and reviews (Norton 2001, Mersfelder & Nichols 2016, Deng et al. 2021). Behavioral dependence liability very low in general population per Bonnet et al. 2018 (0 gabapentin-specific cases without SUD history). Elevated risk in OUD populations per Bastiaens et al. 2016 (26% vs 4%). Dose escalation tendency moderate due to tolerance development and saturable absorption encouraging higher doses.

Evidence basis: published_case_series

Withdrawal Profiletrace

FieldPublishedAI ProposedConfidence
Severitymoderatemoderatemedium
Symptomsanxiety, insomnia, nausea, diaphoresis, tremor, agitation, palpitations, hypertension, seizuresanxiety, insomnia, nausea, diaphoresis, tremor, agitation, palpitations, hypertension, seizuresmedium
FatalNoNomedium
Medical SupervisionRequiredRequiredmedium
Editorial

Withdrawal documented by Norton 2001, Mersfelder & Nichols 2016. Onset typically 12–48 hours after abrupt cessation. Seizures reported in some cases, warranting medical supervision. One severe case required 18-month taper (Deng et al. 2021). Total duration estimated at up to 2 weeks for most cases, though protracted withdrawal is possible.

Reasoning

Withdrawal documented by Norton 2001, Mersfelder & Nichols 2016. Onset typically 12–48 hours after abrupt cessation. Seizures reported in some cases, warranting medical supervision. One severe case required 18-month taper (Deng et al. 2021). Total duration estimated at up to 2 weeks for most cases, though protracted withdrawal is possible.

Evidence basis: published_case_series

Tolerance Profiletrace

FieldPublishedAI ProposedConfidence
Buildupmoderatemoderatemedium
Half-life——medium
Full Reset——medium
Cross-tolerancespregabalinpregabalinmedium
Editorial

Tolerance mechanism established in animal data (Yang et al. 2016 — α2δ-1 downregulation). Clinical tolerance observed but not formally quantified in controlled human studies. Full reset timeline of 10.5 days from existing database is unverified. Cross-tolerance with pregabalin inferred from shared target, not directly studied.

Reasoning

Tolerance mechanism established in animal data (Yang et al. 2016 — α2δ-1 downregulation). Clinical tolerance observed but not formally quantified in controlled human studies. Full reset timeline of 10.5 days from existing database is unverified. Cross-tolerance with pregabalin inferred from shared target, not directly studied.

Evidence basis: animal_study

Effects & Profile

Contraindications

FieldPublishedAI ProposedConfidence
respiratory concurrent opioid usetraceabsoluteabsolutehigh
Editorial

Strong evidence from Gomes et al. 2017 (population-based mortality data) and Lyndon et al. 2017 (heroin polydrug risk). Forensic data (Finlayson et al. 2017) confirm gabapentin present in 26% of mixed-drug fatalities alongside opioids.

Reasoning

Strong evidence from Gomes et al. 2017 (population-based mortality data) and Lyndon et al. 2017 (heroin polydrug risk). Forensic data (Finlayson et al. 2017) confirm gabapentin present in 26% of mixed-drug fatalities alongside opioids.

renal renal impairmenttracerelativerelativehigh
Editorial

Well-established from Lal et al. 2012 and Ahmed et al. 2017 PK studies in renal impairment and elderly populations. FDA label includes specific dose adjustment recommendations by creatinine clearance.

Reasoning

Well-established from Lal et al. 2012 and Ahmed et al. 2017 PK studies in renal impairment and elderly populations. FDA label includes specific dose adjustment recommendations by creatinine clearance.

respiratory concurrent benzodiazepine usetracerelativerelativehigh
Editorial

Class-level pharmacodynamic interaction consistent with all CNS depressant combinations. No specific gabapentin+benzodiazepine interaction study published, but mechanism is well-understood. Benedetti 2000 confirms no CYP-mediated interaction.

Reasoning

Class-level pharmacodynamic interaction consistent with all CNS depressant combinations. No specific gabapentin+benzodiazepine interaction study published, but mechanism is well-understood. Benedetti 2000 confirms no CYP-mediated interaction.

respiratory concurrent alcohol usetracerelativerelativehigh
Editorial

Pharmacodynamic additive interaction consistent with CNS depressant class effects. Gabapentin's therapeutic use in alcohol withdrawal (Andrade 2020, Modesto-Lowe et al. 2019) is distinct from unsupervised co-use.

Reasoning

Pharmacodynamic additive interaction consistent with CNS depressant class effects. Gabapentin's therapeutic use in alcohol withdrawal (Andrade 2020, Modesto-Lowe et al. 2019) is distinct from unsupervised co-use.

psychiatric suicidal ideation or depressiontracerelativerelativemedium
Editorial

Based on FDA December 2008 class-wide warning for all antiepileptic drugs (Kanner 2011). Klein et al. 2021 meta-analysis provides additional context. Some studies question applicability of class-wide designation to gabapentin specifically.

Reasoning

Based on FDA December 2008 class-wide warning for all antiepileptic drugs (Kanner 2011). Klein et al. 2021 meta-analysis provides additional context. Some studies question applicability of class-wide designation to gabapentin specifically.

other history of substance use disordertracerelativerelativehigh
Editorial

Bastiaens et al. 2016 found 26% gabapentin misuse in OUD patients vs 4% non-OUD. Evoy et al. 2021 comprehensive review confirms elevated misuse liability in SUD context. McNeilage et al. 2024 qualitative review documents misuse experiences.

Reasoning

Bastiaens et al. 2016 found 26% gabapentin misuse in OUD patients vs 4% non-OUD. Evoy et al. 2021 comprehensive review confirms elevated misuse liability in SUD context. McNeilage et al. 2024 qualitative review documents misuse experiences.

pregnancy breastfeeding pregnancytracerelativerelativemedium
Editorial

Petrere & Anderson 1994 developmental toxicity data in multiple species. No teratogenicity at moderate doses. Limited human data — standard precaution for AEDs in pregnancy.

Reasoning

Petrere & Anderson 1994 developmental toxicity data in multiple species. No teratogenicity at moderate doses. Limited human data — standard precaution for AEDs in pregnancy.

age elderlytracerelativerelativehigh
Editorial

Ahmed et al. 2017 PK study in elderly nursing home patients confirms reduced oral clearance and dose-dependent bioavailability across age groups.

Reasoning

Ahmed et al. 2017 PK study in elderly nursing home patients confirms reduced oral clearance and dose-dependent bioavailability across age groups.

Timeline Phases

oral

FieldPublishedAI ProposedConfidence
Onsettrace1800–7200 sec(i=0.05)1800–7200 sec(i=0.05)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Come uptrace2700–5400 sec(i=0.30)2700–5400 sec(i=0.30)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Peaktrace5400–10800 sec(i=1.00)5400–10800 sec(i=1.00)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Plateautrace3600–7200 sec(i=0.55)3600–7200 sec(i=0.55)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Resolutiontrace3600–7200 sec(i=0.20)3600–7200 sec(i=0.20)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Afterglowtrace7200–14400 sec(i=0.05)7200–14400 sec(i=0.05)medium
Editorial

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Reasoning

Timeline derived from published PK data: Tmax 3–4 hours (Bockbrader et al. 2010), half-life 5–7 hours (Bockbrader et al. 2010; Radulovic et al. 1995), and community-reported total duration of 6–10 hours from existing database. Onset range 30–120 min from existing database; the lower bound (30 min) is plausible but not confirmed by published studies. Phase durations inferred from PK profile and community reports.

Evidence basis: community_consensus_large

Dose Tier Summaries

thresholdtrace
medium

At threshold doses (~200 mg oral), effects are subtle and easily overlooked. A mild sense of relaxation or slight reduction in background anxiety may be noticeable, along with faint sedation that could be mistaken for ordinary tiredness. Mood may shift slightly toward contentment. Physically, mild dizziness is the most likely perceptible effect. No significant motor impairment or cognitive disruption occurs at this level. Sleep quality may be marginally improved if taken in the evening.

Editorial

Threshold value of 200 mg from existing database (community-curated). Subjective description inferred from clinical adverse event data at low therapeutic doses and qualitative misuse literature.

Reasoning

Threshold value of 200 mg from existing database (community-curated). Subjective description inferred from clinical adverse event data at low therapeutic doses and qualitative misuse literature.

Evidence basis: community_consensus_large

lighttrace
medium

At light doses (200–900 mg oral), anxiety suppression becomes clearly perceptible — a noticeable calming effect that distinguishes gabapentin from placebo. Mild sedation develops, with a gentle sense of relaxation and reduced mental tension. Some individuals report early hints of mood elevation or enhanced sociability at the upper end of this range. Physically, dizziness becomes more apparent, and mild motor control impairment may emerge — slight unsteadiness or reduced coordination. Fatigue and drowsiness are common, particularly in opioid-naive individuals or those new to gabapentin. Cognitive function remains largely intact, though thought deceleration may begin at higher light doses. Functional impairment is mild but present. Driving or operating machinery is inadvisable at the upper end of this range. Duration of noticeable effects is approximately 6–8 hours.

Editorial

Light range 200–900 mg from existing database. Effects described from clinical trial adverse event profiles (sedation, dizziness, ataxia at therapeutic doses 300–900 mg/day) and qualitative misuse literature.

Reasoning

Light range 200–900 mg from existing database. Effects described from clinical trial adverse event profiles (sedation, dizziness, ataxia at therapeutic doses 300–900 mg/day) and qualitative misuse literature.

Evidence basis: community_consensus_large

commontrace
medium

At common doses (900–1,500 mg oral), the full gabapentin experience emerges. Anxiety suppression is pronounced — a broad anxiolytic effect that users describe as a warm, diffuse calm. Sedation deepens, and cognitive euphoria or mood elevation becomes noticeable in a substantial proportion of users. Enhanced sociability and reduced social inhibition are frequently reported. Thought deceleration is apparent. Physically, dizziness, motor control impairment, and ataxia are consistently present. Muscle relaxation is noticeable. Nystagmus may occur. Peripheral edema can develop with repeated dosing at this level. Some users report tactile euphoria — a pleasant bodily warmth or lightness. Functional impairment is moderate. Sleep onset is facilitated, and drowsiness persists for the full 6–10 hour duration. This range overlaps with standard clinical therapeutic doses, though recreational users often take the full amount at once rather than in divided doses.

Editorial

Common range 900–1,500 mg from existing database. This overlaps with upper clinical therapeutic doses (900–1,800 mg/day). Subjective effects drawn from McNeilage et al. 2024 qualitative review and Bastiaens et al. 2016 misuse data.

Reasoning

Common range 900–1,500 mg from existing database. This overlaps with upper clinical therapeutic doses (900–1,800 mg/day). Subjective effects drawn from McNeilage et al. 2024 qualitative review and Bastiaens et al. 2016 misuse data.

Evidence basis: community_consensus_large

strongtrace
medium

At strong doses (1,500–2,400 mg oral), gabapentin's depressant and euphorigenic effects intensify substantially. Euphoria is more reliably produced, particularly in individuals with prior opioid experience. Emotional suppression and depersonalization may emerge alongside the anxiolytic and sedative effects. Amnesia becomes possible — gaps in memory for events during the experience. Thought deceleration is pronounced. Physically, significant ataxia and motor control impairment are expected. Dizziness may be marked. Slurred speech and drowsiness are common. Internal hallucinations or dream enhancement have been reported at this range. The opioid-potentiating properties of gabapentin become particularly relevant — co-use at this dose level carries serious respiratory depression risk. Note that gabapentin's saturable absorption means bioavailability drops substantially at higher single doses (~47% at 800 mg, decreasing further above). Taking the full amount at once produces less plasma exposure than the dose would suggest. Some users stagger doses to circumvent this ceiling.

Editorial

Strong range 1,500–2,400 mg from existing database. Euphoria and opioid potentiation effects drawn from Bastiaens et al. 2016, Lyndon et al. 2017, and McNeilage et al. 2024. Saturable absorption data from Bockbrader et al. 2010.

Reasoning

Strong range 1,500–2,400 mg from existing database. Euphoria and opioid potentiation effects drawn from Bastiaens et al. 2016, Lyndon et al. 2017, and McNeilage et al. 2024. Saturable absorption data from Bockbrader et al. 2010.

Evidence basis: community_consensus_large

heavytrace
medium

At heavy doses (2,400+ mg oral), gabapentin produces maximal sedation, pronounced euphoria (in susceptible individuals), and significant cognitive impairment. Amnesia is likely. Depersonalization and emotional suppression may be prominent. Internal hallucinations or vivid dream-like states have been reported. The overall experience is one of deep, diffuse CNS depression with a dissociative quality at the upper extreme. Physically, severe ataxia, marked dizziness, nystagmus, slurred speech, and somnolence are expected. Motor function is substantially impaired. The risk of falls and injury is elevated. Due to saturable absorption, bioavailability at these doses falls to approximately 33% or below — actual plasma exposure is far less than dose-proportional. This range carries the highest risk of adverse outcomes, particularly when combined with opioids, benzodiazepines, or alcohol. Respiratory depression risk from pharmacodynamic synergy with co-administered CNS depressants is the primary safety concern.

Editorial

Heavy range 2,400+ mg from existing database. Effects described from adverse event data at supratherapeutic doses, qualitative misuse literature (McNeilage et al. 2024), and forensic case data. Bioavailability ceiling from Bockbrader et al. 2010.

Reasoning

Heavy range 2,400+ mg from existing database. Effects described from adverse event data at supratherapeutic doses, qualitative misuse literature (McNeilage et al. 2024), and forensic case data. Bioavailability ceiling from Bockbrader et al. 2010.

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

6 strong · 28 moderate · 8 weak
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    moderate
    The novel anticonvulsant drug, gabapentin (Neurontin), binds to the alpha2delta subunit of a calcium channel
    Gee NS, Brown JP, Dissanayake VU, Offord J, Thurlow R, Woodruff GN · 1996 · The Journal of Biological Chemistry
    pubmed 86214445 claims checked3 verified2 inconclusive
  2. [2]
    weak
    Gabapentin: history and synthesis (Satzinger and Hartenstein 1975)
    Satzinger G, Hartenstein R · 1975
    linkno claims checked
  3. [3]
    weak
    Gabapentin withdrawal syndrome
    Norton JW · 2001 · Clinical Neuropharmacology
    pubmed 114793992 claims checked1 verified1 inconclusive
  4. [4]
    weak
    Gabapentin LD50 and toxicity in rodents - FDA label and preclinical data
    FDA / Pfizer · 2017
    linkno claims checked
  5. [5]
    moderate
    Gabapentin, opioids, and the risk of opioid-related death: A population-based nested case-control study
    Gomes T, Juurlink DN, Antoniou T, Mamdani MM, Paterson JM, van den Brink W · 2017 · PLoS Medicine
    doi.org/10.1371/journal.pmed.1002396pubmed 289729834 claims checked4 verified
  6. [6]
    moderate
    A comparison of the pharmacokinetics and pharmacodynamics of pregabalin and gabapentin
    Bockbrader HN, Wesche D, Miller R, Chapel S, Janiczek N, Burger P · 2010 · Clinical Pharmacokinetics
    doi.org/10.2165/11536200-000000000-00000pubmed 208188327 claims checked7 verified
  7. [7]
    moderate
    Gabapentin inhibits high-threshold calcium channel currents in cultured rat dorsal root ganglion neurones
    Sutton KG, Martin DJ, Pinnock RD, Lee K, Scott RH · 2002 · British Journal of Pharmacology
    pubmed 117865023 claims checked2 verified1 inconclusive
  8. [8]
    strong
    Structural basis for CaVα2δ:gabapentin binding
    Chen Z, Mondal A, Minor DL · 2023 · Nature Structural & Molecular Biology
    doi.org/10.1038/s41594-023-00951-7pubmed 369735102 claims checked2 verified
  9. [9]
    moderate
    The increased trafficking of the calcium channel subunit alpha2delta-1 to presynaptic terminals in neuropathic pain is inhibited by the alpha2delta ligand pregabalin.
    Bauer CS, Nieto-Rostro M, Rahman W, et al. · 2009 · Journal of Neuroscience
    doi.org/10.1523/jneurosci.0356-09.2009pubmed 193396034 claims checked4 verified
  10. [10]
    moderate
    Abuse of Gabapentin is Associated with Opioid Addiction
    Bastiaens L, Galus J, Mazur C · 2016 · The Psychiatric Quarterly
    pubmed 268878554 claims checked2 verified2 inconclusive
  11. [11]
    moderate
    Gabapentinoid Insensitivity after Repeated Administration is Associated with Down-Regulation of the α2δ-1 Subunit in Rats
    Yang Y, Yang F, Yang F, Li CL, Wang Y, Li Z, et al. · 2016 · Neuroscience Bulletin
    doi.org/10.1007/s12264-015-0008-3pubmed 267818783 claims checked3 verified
  12. [12]
    weak
    A Comprehensive Analysis of Jurisdiction-Specific Laws Related to Scheduling or Required Prescription Drug Monitoring of Gabapentin in the United States, 2016-2024
    Various · 2025
    linkno claims checked
  13. [13]
    weak
    UK reclassification of gabapentin as Class C Schedule 3 controlled drug
    UK Government / Drugs and Alcohol Ireland · 2019
    linkno claims checked
  14. [14]
    weak
    Gabapentin physical properties: crystal structure, melting point, solubility
    Multiple sources (MDPI Crystals, PubChem, Sigma-Aldrich) · 2024
    linkno claims checked
  15. [15]
    moderate
    Upregulation of Dorsal Root Ganglion α2δ Calcium Channel Subunit and Its Correlation with Allodynia in Spinal Nerve-Injured Rats
    Luo ZD, Chaplan SR, Higuera ES, Sorkin LS, Stauderman KA · 2001 · Journal of Neuroscience
    doi.org/10.1523/jneurosci.21-06-01868.20013 claims checked3 verified
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    moderate
    Mechanisms of the gabapentinoids and alpha2delta-1 calcium channel subunit in neuropathic pain
    Patel R, Dickenson AH · 2016 · Pharmacology Research & Perspectives
    doi.org/10.1002/prp2.205pubmed 270696262 claims checked1 verified1 inconclusive
  17. [17]
    moderate
    Enzyme induction and inhibition by new antiepileptic drugs: a review of human studies
    Benedetti MS · 2000 · Fundamental & Clinical Pharmacology
    pubmed 110304374 claims checked2 verified2 inconclusive
  18. [18]
    moderate
    Disposition of gabapentin (neurontin) in mice, rats, dogs, and monkeys
    Radulovic LL, Turck D, von Hodenberg A, et al. · 1995 · Drug Metabolism and Disposition
    pubmed 76009096 claims checked3 verified3 inconclusive
  19. [19]
    moderate
    Clinical pharmacokinetics of gabapentin after administration of gabapentin enacarbil extended-release tablets in patients with varying degrees of renal function
    Lal R, Sukbuntherng J, Luo W, et al. · 2012 · Clinical Therapeutics
    doi.org/10.1016/j.clinthera.2011.12.004pubmed 222067943 claims checked3 verified
  20. [20]
    moderate
    Pharmacokinetics and Saturable Absorption of Gabapentin in Nursing Home Elderly Patients
    Ahmed GF, Bathena SP, Brundage RC, Leppik IE, Conway JM, Schwartz JB, Birnbaum AK · 2017 · The AAPS Journal
    doi.org/10.1208/s12248-016-0022-zpubmed 280707162 claims checked1 verified1 inconclusive
  21. [21]
    moderate
    Population pharmacokinetics of gabapentin in healthy Korean subjects with influence of genetic polymorphisms of ABCB1
    Tran P, Yoo HD, Ngo L, Cho HY, Lee YB · 2017 · Journal of Pharmacokinetics and Pharmacodynamics
    doi.org/10.1007/s10928-017-9549-6pubmed 290189996 claims checked6 verified
  22. [22]
    moderate
    Biochemistry and physiology of voltage-gated calcium channel trafficking: a target for gabapentinoid drugs
    Dolphin AC · 2025 · Open Biology
    doi.org/10.1098/rsob.250013pubmed 406642381 claim checked1 inconclusive
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    Gabapentin for Alcohol-Related Disorders: Critical Appraisal of the Symptom-Driven Approach
    Andrade C · 2020 · The Journal of Clinical Psychiatry
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    pubmed 94515091 claim checked1 verified
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    Lal R, Ellenbogen A, Gidal B · 2022 · Therapeutic Drug Monitoring
    doi.org/10.1097/ftd.0000000000000935pubmed 347261991 claim checked1 inconclusive
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    Gabapentin for chronic neuropathic pain in adults
    Wiffen PJ, Derry S, Bell RF, Rice AS, Tölle TR, Phillips T, Moore RA · 2017 · The Cochrane Database of Systematic Reviews
    doi.org/10.1002/14651858.cd007938.pub4pubmed 285974711 claim checked1 verified
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    Gabapentinoids and Neuropathic Pain: Evaluation of the Quality of Randomised Controlled Trials: An Umbrella Review
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    doi.org/10.1111/fcp.70052pubmed 413853951 claim checked1 verified
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    The Effect of Gabapentin on Acute Postoperative Pain in Patients Undergoing Total Knee Arthroplasty: A Meta-Analysis
    Zhai L, Song Z, Liu K · 2016 · Medicine
    doi.org/10.1097/md.0000000000003673pubmed 271964731 claim checked1 verified
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    Adjunctive pregabalin vs gabapentin for focal seizures: Interpretation of comparative outcomes
    French J, Glue P, Friedman D, Almas M, Yardi N, Knapp L, Pitman V, Posner HB · 2016 · Neurology
    doi.org/10.1212/wnl.0000000000003118pubmed 27521437no claims checked
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    Gabapentin for alcohol use disorder: A good option, or cause for concern?
    Modesto-Lowe V, Barron GC, Aronow B, Chaplin M · 2019 · Cleveland Clinic Journal of Medicine
    doi.org/10.3949/ccjm.86a.18128pubmed 318211392 claims checked1 verified1 inconclusive
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    Suicide by gabapentin overdose
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    doi.org/10.1111/j.1556-4029.2011.01798.xpubmed 215543101 claim checked1 verified
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    doi.org/10.1016/j.drugalcdep.2019.107709pubmed 317322951 claim checked1 verified
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.

summary10 claims7verified3inconclusive
inconclusiveDespite its structural derivation from γ-aminobutyric acid (GABA), it does not interact with GABA receptors, transporters, or metabolic enzymes[1]model confidence 70%
Inconclusive

The abstract establishes gabapentin binds α2δ subunit of VGCCs, but does not explicitly state that gabapentin does NOT interact with GABA receptors, transporters, or metabolic enzymes. The GABA non-interaction claim would require full-text data.

[3H]gabapentin is the first pharmacological agent described interacting with an alpha2delta subunit of a voltage-dependent Ca2+ channel.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedAbsorption is saturable and dose-dependent: bioavailability falls from approximately 60% at 900 mg/day to approximately 33% at 3,600 mg/day.[6]model confidence 100%
Verified

Abstract explicitly states bioavailability drops 60% to 33% as dose increases 900–3600 mg/day, directly matching the claim.

Bioavailability drops 60% to 33% as dose increases 900-3600 mg/day.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedIts molecular target — the α2δ-1 subunit of voltage-gated calcium channels — was not identified until 1996, two decades after synthesis.[1]model confidence 90%
Verified

Abstract confirms this is the first identification of the α2δ subunit as gabapentin's binding site. The SCOPE confirms 1996 as the year of this landmark discovery.

First identification of alpha2delta subunit as the gabapentin binding site.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedGabapentin binds the α2δ-1 subunit of high-voltage-activated calcium channels, inhibiting whole-cell calcium current with an IC50 of 167 nM in dorsal root ganglion neurons[7]model confidence 100%
Verified

Abstract explicitly confirms IC50 of 167 nM for inhibiting Ca2+ channel current in rat DRG neurons via the alpha2delta subunit.

Gabapentin IC50 167 nM for inhibiting Ca2+ channel current in rat DRG neurons via alpha2delta subunit.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedCryo-EM structures reveal a binding pocket in the dCache1 domain of CaVα2δ-1 that completely encapsulates the molecule[8]model confidence 100%
Verified

Abstract explicitly describes a binding pocket in the dCache1 domain that completely encapsulates gabapentin, as revealed by cryo-EM.

Cryo-EM structure of the gabapentin-bound CaV1.2/CaVβ3/CaVα2δ-1 channel reveals a binding pocket in the dCache1 domain that completely encapsulates gabapentin.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe drug inhibits anterograde trafficking of α2δ-1 to presynaptic terminals, reducing neurotransmitter release in sensitized pain pathways.[9]model confidence 100%
Verified

Abstract directly states gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals, reducing neurotransmitter release.

Gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals, reducing neurotransmitter release and spinal sensitization.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveAt supratherapeutic doses, euphoria, enhanced sociability, and opioid potentiation are reported — particularly among individuals with opioid use disorder[10]model confidence 60%
Inconclusive

Abstract confirms elevated misuse in OUD populations (26% vs 4%) but does not describe specific subjective effects such as euphoria, enhanced sociability, or opioid potentiation.

26% of patients with OUD reported gabapentin misuse vs 4% without OUD (p<0.0001).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe principal mortality risk is pharmacodynamic: co-use with opioids significantly increases opioid-related death[5]model confidence 90%
Verified

Abstract confirms that co-prescription with opioids significantly increases risk of opioid-related death. 'Pharmacodynamic' mechanism is a reasonable inference not contradicted.

Co-prescription of gabapentin with opioids significantly increases risk of opioid-related death.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusivePhysical dependence develops with prolonged use; withdrawal includes anxiety, insomnia, and seizures[3]model confidence 65%
Inconclusive

Abstract confirms withdrawal syndrome exists after abrupt discontinuation, but does not enumerate specific symptoms (anxiety, insomnia, seizures). These details may be in the full case reports.

Three case reports of withdrawal symptoms after abrupt gabapentin discontinuation. Recommends tapering, especially at high doses.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedTolerance involves α2δ-1 subunit downregulation in thalamus and spinal cord, though no controlled human study has quantified the reset timeline[11]model confidence 90%
Verified

Abstract confirms α2δ-1 downregulation in thalamus and spinal dorsal horn associated with gabapentin insensitivity after repeated administration in animal model. The 'no controlled human study' qualifier is not contradicted.

α2δ-1 down-regulation in thalamus/spinal dorsal horn associated with GBP insensitivity after repeated administration in rat model.

checked by claude-sonnet-4-6 · Apr 28, 2026

history1 claim1verified
verifiedThe landmark identification of the α2δ subunit of voltage-gated calcium channels as the binding target came only in 1996, when Gee and colleagues isolated and characterized the [³H]gabapentin-binding protein from pig cerebral cortex.[1]model confidence 95%
Verified

Abstract confirms first identification of α2δ as gabapentin's binding site, with binding protein isolated from pig cerebral cortex. SCOPE confirms 1996 as the year.

First identification of alpha2delta subunit as the gabapentin binding site. Binding protein isolated from pig cerebral cortex, purified 1022-fold.

checked by claude-sonnet-4-6 · Apr 28, 2026

pharmacology18 claims13verified5inconclusive
inconclusiveDespite its structural resemblance to GABA, gabapentin does not bind GABA-A receptors, GABA-B receptors, GABA transporters, or GABA transaminase[1]model confidence 70%
Inconclusive

Abstract identifies α2δ as gabapentin's binding site but does not explicitly enumerate that gabapentin does not bind GABA receptors or transporters. Full text likely contains this assertion.

[3H]gabapentin is the first pharmacological agent described interacting with an alpha2delta subunit of a voltage-dependent Ca2+ channel.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveIt does not directly open or block voltage-gated sodium channels, and it undergoes no significant hepatic metabolism or CYP enzyme interaction.[17]model confidence 65%
Inconclusive

Abstract supports the CYP non-interaction claim but does not address voltage-gated sodium channel activity. Only half of the compound claim is verifiable from this abstract.

Gabapentin, vigabatrin, and levetiracetam are devoid of significant CYP enzyme inducing or inhibiting properties in humans.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe functional consequence of α2δ-1 binding is inhibition of anterograde trafficking of the subunit to presynaptic terminals, which reduces calcium influx and neurotransmitter release at hyperexcitable synapses[9]model confidence 95%
Verified

Abstract directly states gabapentinoids inhibit anterograde trafficking and reduce neurotransmitter release. Reduced calcium influx is the mechanistic implication of fewer presynaptic channels.

Gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals, reducing neurotransmitter release and spinal sensitization.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedIn neuropathic pain states, peripheral nerve injury causes >17-fold upregulation of α2δ-1 expression in dorsal root ganglia ipsilateral to injury — an upregulation that precedes the onset of allodynia[15]model confidence 100%
Verified

Abstract explicitly states >17-fold increase in alpha2delta subunit in DRGs ipsilateral to nerve injury preceding allodynia onset.

>17-fold increase in alpha2delta subunit in DRGs ipsilateral to nerve injury preceding allodynia onset.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedElectrophysiological studies in rat dorsal root ganglion neurons demonstrate gabapentin inhibits whole-cell calcium channel current with an IC50 of 167 nM[7]model confidence 100%
Verified

Abstract explicitly states IC50 of 167 nM for inhibiting Ca2+ channel current in rat DRG neurons.

Gabapentin IC50 167 nM for inhibiting Ca2+ channel current in rat DRG neurons via alpha2delta subunit.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedEffects are neuron-type-specific across spinal cord and higher brain centers, with a number needed to treat (NNT) averaging 3–8 across neuropathic pain indications.[16]model confidence 90%
Verified

Abstract confirms NNT 3–8 across neuropathies and notes only alpha2delta-1 (not alpha2delta-2) is implicated in neuropathy, consistent with neuron-type specificity.

Gabapentinoids bind alpha2delta-1 and alpha2delta-2; only alpha2delta-1 implicated in neuropathy. NNT 3-8 across neuropathies.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedBioavailability falls from approximately 60% at 900 mg/day to approximately 33% at 3,600 mg/day[6]model confidence 100%
Verified

Abstract explicitly states bioavailability drops from 60% to 33% as dose increases from 900 to 3600 mg/day.

Bioavailability drops 60% to 33% as dose increases 900-3600 mg/day.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPeak plasma concentration (Tmax) occurs at 3–4 hours after oral administration[6]model confidence 100%
Verified

Abstract explicitly states Tmax of 3–4 hours after oral administration.

Gabapentin Tmax 3-4 hours (oral).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPopulation pharmacokinetic modeling describes a one-compartment model with lag time of approximately 0.311 hours[21]model confidence 100%
Verified

Abstract explicitly confirms one-compartment model with lag time of 0.311 h.

One-compartment model; ... lag time 0.311 h.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPlasma protein binding is less than 3%[18]model confidence 100%
Verified

Abstract explicitly states plasma protein binding <3%.

Plasma protein binding <3%.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPlasma protein binding is less than 3%[6]model confidence 90%
Verified

Abstract states gabapentin is 'not protein-bound', consistent with <3% protein binding.

Not protein-bound.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedVolume of distribution is approximately 81 L in healthy subjects.[21]model confidence 100%
Verified

Abstract explicitly reports Vd of 81.0 L in healthy Korean subjects.

Vd 81.0 L.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedElimination half-life is 5–7 hours in humans[6]model confidence 100%
Verified

Abstract states half-life of approximately 6 hours, which falls within the claimed 5–7 hour range.

Half-life ~6 hours.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveElimination half-life is 5–7 hours in humans[18]model confidence 50%
Inconclusive

Abstract reports only animal IV half-lives (rat 1.7h, dog 2.9h, monkey 3.0h). No human data are present. Animal half-lives do not support the human 5–7h claim.

IV half-life 1.7h (rat), 2.9h (dog), 3.0h (monkey).

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveIn dogs, N-methylgabapentin accounts for approximately 34% of the dose, but in humans, metabolism is minimal (<5%)[18]model confidence 60%
Inconclusive

Abstract confirms N-methylgabapentin ~34% in dogs and minimal metabolism in other animal species, but this is an animal study with no human data. The human <5% claim cannot be verified.

Metabolism minimal except dogs (N-methylgabapentin ~34%).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedGabapentin does not induce or inhibit any major human hepatic CYP isoenzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4), resulting in an exceptionally clean drug–drug interaction profile from a pharmacokinetic standpoint.[17]model confidence 90%
Verified

Abstract confirms gabapentin is devoid of significant CYP enzyme inducing or inhibiting properties in humans, supporting the claim even though individual isoenzymes are not listed.

Gabapentin, vigabatrin, and levetiracetam are devoid of significant CYP enzyme inducing or inhibiting properties in humans.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedElimination is directly proportional to creatinine clearance, and dose reduction is mandatory in renal impairment.[19]model confidence 100%
Verified

Abstract directly states gabapentin clearance is proportional to CrCL and that dosing adjustments are required for renal impairment.

Gabapentin cleared via renal excretion proportional to creatinine clearance (CrCL). Dosing adjustments required for renal impairment.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveElimination is directly proportional to creatinine clearance, and dose reduction is mandatory in renal impairment.[20]model confidence 60%
Inconclusive

Abstract demonstrates reduced clearance in elderly patients with reduced renal function, implying dose adjustment, but does not explicitly state CrCL proportionality or mandatory dose reduction.

CL 2.93 L/h in elderly NH patients (lower than general population, reflecting reduced renal function).

checked by claude-sonnet-4-6 · Apr 28, 2026

neuroscience7 claims3verified4inconclusive
inconclusiveNon-pain indications: The mechanism by which gabapentin reduces alcohol craving and withdrawal symptoms is unclear. Reduced glutamatergic excitotoxicity via presynaptic calcium channel modulation is hypothesized but unconfirmed.[23]model confidence 50%
Inconclusive

Abstract covers clinical efficacy (RCT meta-analyses) but does not discuss the neurobiological mechanism or the glutamatergic hypothesis. Mechanism details are not in this abstract.

Meta-analyses of RCTs: gabapentin reduces alcohol withdrawal severity and percentage of heavy drinking days, but small effect.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedBy binding α2δ-1 subunits and preventing their trafficking to the presynaptic membrane, gabapentin reduces high-voltage-activated calcium channel density at synapses that have undergone pathological sensitization[9]model confidence 90%
Verified

Abstract confirms inhibition of anterograde trafficking to presynaptic terminals, reducing neurotransmitter release and spinal sensitization. Reduced channel density is the direct mechanistic implication.

Gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals, reducing neurotransmitter release and spinal sensitization.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedIn neuropathic pain models, peripheral nerve injury triggers >17-fold upregulation of α2δ-1 in ipsilateral dorsal root ganglion neurons, creating a pathological excess of presynaptic calcium channels[15]model confidence 90%
Verified

Abstract confirms >17-fold upregulation in ipsilateral DRGs after nerve injury. The resulting pathological excess of presynaptic channels is a reasonable mechanistic inference.

>17-fold increase in alpha2delta subunit in DRGs ipsilateral to nerve injury preceding allodynia onset.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveThe supraspinal mechanisms underlying gabapentin's anxiolytic and sedative effects are less well characterized. α2δ-1 is widely expressed in cortical, thalamic, and limbic structures[22]model confidence 50%
Inconclusive

Abstract reviews α2δ subunit trafficking and gabapentinoid mechanism but does not specifically describe α2δ-1 distribution in cortical, thalamic, and limbic structures or supraspinal mechanisms of anxiolysis/sedation.

Reviews α2δ subunit role in VGCC trafficking and function; discusses gabapentinoid mechanism including α2δ ligands preventing channel trafficking.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveGabapentin's efficacy in neuropathic pain maps onto the central sensitization framework: nerve injury upregulates α2δ-1, increasing excitatory neurotransmission in dorsal horn circuits; gabapentin reverses this pathological amplification by reducing the supply of presynaptic calcium channels.[16]model confidence 55%
Inconclusive

Abstract confirms alpha2delta-1 is implicated in neuropathy and provides NNT data, but does not describe the central sensitization framework, dorsal horn circuit specifics, or the pathological amplification mechanism.

Gabapentinoids bind alpha2delta-1 and alpha2delta-2; only alpha2delta-1 implicated in neuropathy. NNT 3-8 across neuropathies.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedTolerance mechanisms in humans: Animal data demonstrate α2δ-1 downregulation with chronic gabapentin use, but no controlled human study has quantified the timeline or extent of clinical tolerance development.[11]model confidence 90%
Verified

Abstract confirms α2δ-1 downregulation in thalamus/spinal dorsal horn in rat model. The claim correctly characterizes this as animal data and notes the absence of controlled human studies, which is not contradicted.

α2δ-1 down-regulation in thalamus/spinal dorsal horn associated with GBP insensitivity after repeated administration in rat model.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveEuphoriant mechanism: The neurobiological basis for gabapentin-induced euphoria — reported predominantly in opioid use disorder populations — remains unexplained. Whether this involves indirect effects on reward circuitry or direct α2δ-1-mediated modulation of mesolimbic pathways is unknown.[10]model confidence 50%
Inconclusive

Abstract establishes prevalence of gabapentin misuse in OUD populations but does not address the neurobiological mechanism of euphoria or reward circuitry involvement.

26% of patients with OUD reported gabapentin misuse vs 4% without OUD (p<0.0001).

checked by claude-sonnet-4-6 · Apr 28, 2026

receptor pharmacology6 claims5verified1inconclusive
verifiedGee and colleagues first isolated and characterized the [³H]gabapentin-binding protein in 1996 from pig cerebral cortex, purifying it 1,022-fold[1]model confidence 100%
Verified

Abstract confirms binding protein isolated from pig cerebral cortex, purified 1022-fold, and [3H]gabapentin as the pharmacological agent.

Binding protein isolated from pig cerebral cortex, purified 1022-fold. [3H]gabapentin is the first pharmacological agent described interacting with an alpha2delta subunit.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedBrown and colleagues subsequently developed a refined radioligand binding assay using [³H]leucine that confirmed the high-affinity interaction with the purified α2δ subunit from porcine brain.[24]model confidence 100%
Verified

Abstract confirms purification of α2δ from porcine brain, novel binding assay using L-[3H]leucine/L-isoleucine, and high-affinity gabapentin binding.

Purification of alpha2delta Ca2+ channel subunit from porcine brain. Novel binding assay using L-[3H]leucine/L-isoleucine validated. Confirms gabapentin binds alpha2delta with high affinity.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedChen, Mondal, and Minor published the cryo-EM structure of gabapentin bound to the brain/cardiac CaV1.2/CaVβ3/CaVα2δ-1 channel complex in 2023[8]model confidence 90%
Verified

Abstract confirms cryo-EM structure of gabapentin bound to CaV1.2/CaVβ3/CaVα2δ-1 complex. Author names and year not in abstract but the structural finding is confirmed.

Cryo-EM structure of the gabapentin-bound CaV1.2/CaVβ3/CaVα2δ-1 channel reveals a binding pocket in the dCache1 domain.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveInhibition by gabapentin is competitively reduced by L-isoleucine (a substrate for the same amino acid transporter), confirming that gabapentin accesses its binding site through the system L transporter pathway.[7]model confidence 50%
Inconclusive

Abstract covers IC50 and channel types inhibited but does not mention L-isoleucine competitive reduction or the system L transporter pathway. These mechanistic details are not in the abstract.

Gabapentin IC50 167 nM for inhibiting Ca2+ channel current in rat DRG neurons via alpha2delta subunit.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedBeyond acute channel modulation, gabapentin exerts a distinct chronic mechanism: inhibition of α2δ-1 anterograde trafficking from neuronal cell bodies to presynaptic terminals[9]model confidence 100%
Verified

Abstract directly states gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals.

Gabapentinoids inhibit anterograde trafficking of alpha2delta-1 to presynaptic terminals, reducing neurotransmitter release and spinal sensitization.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedIn neuropathic pain states, α2δ-1 is pathologically upregulated (>17-fold in spinal nerve-ligation models), leading to excessive presynaptic calcium channel expression, increased neurotransmitter release, and spinal sensitization[15]model confidence 85%
Verified

Abstract confirms >17-fold upregulation in DRGs ipsilateral to nerve injury. The downstream consequences (excessive presynaptic channels, increased NT release, spinal sensitization) are mechanistic inferences consistent with the upstream finding.

>17-fold increase in alpha2delta subunit in DRGs ipsilateral to nerve injury preceding allodynia onset.

checked by claude-sonnet-4-6 · Apr 28, 2026

pharmacokinetic detail11 claims9verified2inconclusive
verifiedGenetic polymorphisms in ABCB1 (specifically 2677G>T/A) significantly influence the absorption rate constant[21]model confidence 95%
Verified

Abstract explicitly states ABCB1 2677G>T/A affects absorption in the population PK model.

ABCB1 2677G>T/A affects absorption.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSources: ; .[21]model confidence 70%
Verified

The cited paper provides key population PK data (one-compartment model, Vd, clearance, lag time, ABCB1 effects) consistent with use as a source for pharmacokinetic parameters.

One-compartment model; bioavailability 68.8% at 300mg... Oral clearance 11.1 L/h, Vd 81.0 L.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSources: ; .[6]model confidence 70%
Verified

The cited paper provides definitive PK comparison data (Tmax, bioavailability, half-life, protein binding) appropriate for use as a pharmacokinetic source.

Gabapentin Tmax 3-4 hours (oral), saturable nonlinear absorption. Bioavailability drops 60% to 33%.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveGabapentin enacarbil (Horizant), a prodrug formulation, circumvents the saturable transporter by using high-capacity nutrient transporters (MCT-1 and SMVT) for absorption, achieving approximately 75% bioavailability with linear pharmacokinetics[25]model confidence 55%
Inconclusive

Abstract confirms dose-proportional (linear) PK and less variability for gabapentin enacarbil, but does not mention 75% bioavailability, MCT-1, or SMVT transporters.

Gabapentin enacarbil prodrug provides sustained dose-proportional exposure with less variability than immediate-release gabapentin.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedMinimal protein binding (<3%) eliminates displacement interactions with highly bound drugs[18]model confidence 90%
Verified

Abstract confirms plasma protein binding <3%, which supports the claim that displacement interactions are eliminated.

Plasma protein binding <3%.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe large volume of distribution (~81 L) indicates extensive tissue distribution.[21]model confidence 90%
Verified

Abstract reports Vd of 81.0 L. This value substantially exceeds plasma volume (~3L), consistent with the inference of tissue distribution.

Vd 81.0 L.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveIn dogs, N-methylgabapentin accounts for approximately 34% of the administered dose, but in humans and other species (mice, rats, monkeys), metabolism constitutes less than 5% of elimination.[18]model confidence 60%
Inconclusive

Abstract confirms N-methylgabapentin ~34% in dogs and minimal metabolism in mice, rats, monkeys, but this is an animal study. The specific human claim (<5%) cannot be verified from this abstract.

Metabolism minimal except dogs (N-methylgabapentin ~34%).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSources: ; ; .[18]model confidence 70%
Verified

The cited animal PK paper provides protein binding, half-life, bioavailability, and metabolism data appropriate for use as a pharmacokinetic source.

Oral bioavailability: 79% in mice/rats at 50 mg/kg, 80% in dogs, 40% in monkeys. Plasma protein binding <3%.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSources: ; ; .[21]model confidence 70%
Verified

The cited human PK paper provides one-compartment model parameters, ABCB1 influence, and bioavailability data appropriate for use as a pharmacokinetic source.

One-compartment model; bioavailability 68.8% at 300mg, 62.7% at 400mg, 47.1% at 800mg.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedDose reduction is mandatory in patients with reduced renal function[19]model confidence 100%
Verified

Abstract explicitly states dosing adjustments are required for renal impairment.

Dosing adjustments required for renal impairment.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedDose reduction is mandatory in patients with reduced renal function[20]model confidence 80%
Verified

Abstract demonstrates reduced clearance (2.93 L/h) in elderly nursing home patients due to reduced renal function. A knowledgeable reader would infer dose reduction is required.

CL 2.93 L/h in elderly NH patients (lower than general population, reflecting reduced renal function).

checked by claude-sonnet-4-6 · Apr 28, 2026

clinical evidence6 claims6verified
verifiedA meta-analysis of 6 randomized controlled trials (769 patients) demonstrated that gabapentin reduces visual analog scale (VAS) pain scores at 24 and 48 hours after total knee arthroplasty and reduces morphine consumption (mean difference −8.28 mg at 24 hours)[28]model confidence 100%
Verified

Abstract confirms meta-analysis of 6 studies, 769 patients, pain reduction at 24h and 48h, and morphine consumption MD of −8.28 mg at 24h.

Meta-analysis of 6 studies (769 patients): gabapentin superior pain relief at 24h and 48h; reduced cumulative morphine consumption at 24h (MD -8.28 mg).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedMeta-analyses show a small but significant reduction in alcohol withdrawal severity with gabapentin[23]model confidence 100%
Verified

Abstract explicitly states meta-analyses show gabapentin reduces alcohol withdrawal severity, with a small effect.

Meta-analyses of RCTs: gabapentin reduces alcohol withdrawal severity and percentage of heavy drinking days, but small effect.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe Cochrane systematic review (2017) provides the highest-quality evidence for gabapentin efficacy in chronic neuropathic pain[26]model confidence 90%
Verified

Abstract confirms this is a Cochrane systematic review demonstrating gabapentin efficacy in postherpetic neuralgia and diabetic neuropathy. The umbrella review (Pair 78) establishes it as the highest-quality review.

Cochrane systematic review: gabapentin ≥1200mg/day provides substantial benefit (≥50% pain relief) vs placebo in postherpetic neuralgia (RR 1.8) and painful diabetic neuropathy (RR 1.9).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedAn umbrella review of gabapentinoid meta-analyses found that 14 of 16 reviews rated "critically low" quality by AMSTAR 2 criteria; the Cochrane review was the exception.[27]model confidence 100%
Verified

Abstract explicitly states 14 of 16 meta-analyses rated 'critically low' by AMSTAR 2, with the Cochrane review identified as the best evidence.

Umbrella review of 16 meta-analyses: 14 'critically low' quality by AMSTAR 2. Best evidence: Cochrane review.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedCurrent evidence supports gabapentin only as a second-line agent for alcohol-related disorders.[30]model confidence 100%
Verified

Abstract explicitly recommends gabapentin as second-line after standard therapies for AUD.

Recommend as second-line after standard therapies.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedGabapentin demonstrates anxiolytic effects in clinical populations and is used off-label for generalized anxiety disorder and social phobia[31]model confidence 90%
Verified

Abstract confirms controlled trial evidence for gabapentin in social phobia and its potential as anxiolytic in off-label use for anxiety disorders.

Controlled trial evidence for gabapentin in social phobia. Gabapentin shows potential as anxiolytic in off-label use.

checked by claude-sonnet-4-6 · Apr 28, 2026

safety26 claims20verified6inconclusive
verifiedThe first reported fatality attributed to gabapentin alone involved a 62-year-old woman with depression whose postmortem peripheral blood concentration was 88 µg/mL — approximately 4–44× the therapeutic range of 2–20 µg/mL[33]model confidence 90%
Verified

Abstract confirms first reported death solely due to gabapentin, 62-year-old woman, postmortem peripheral blood gabapentin 88 µg/mL. The 4–44× therapeutic range calculation is derived from the confirmed concentration.

First reported death due solely to gabapentin toxicity. 62-year-old woman, postmortem peripheral blood gabapentin 88 µg/mL. No other significant toxic drugs.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveForensic analysis of 180 mixed-drug fatalities in Michigan found gabapentin present in 46 cases (26%), always co-occurring with opioids[34]model confidence 60%
Inconclusive

Abstract confirms n=46 cases with gabapentin and 100% opioid co-occurrence, but does not state a total of 180 fatalities or calculate the 26% prevalence figure. These details are not verifiable from the abstract.

Gabapentin present in 100% of cases where it appeared in mixed drug fatalities (n=46), an opiate was also present.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedA population-based nested case-control study confirmed this association at a population level[5]model confidence 100%
Verified

Abstract directly describes a population-based nested case-control study confirming gabapentin+opioid co-prescription increases opioid-related death risk.

Population-based nested case-control study: co-prescription of gabapentin with opioids significantly increases risk of opioid-related death.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedGabapentinoid use by heroin users substantially increases overdose risk.[35]model confidence 100%
Verified

Abstract explicitly states gabapentinoids potentiate heroin effects and increase overdose risk.

Gabapentinoids potentiate heroin effects and increase overdose risk.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedNo adverse fetal effects were observed in mice (up to 3,000 mg/kg) or rats (up to 1,500 mg/kg)[36]model confidence 100%
Verified

Abstract explicitly states no adverse fetal effects in mice (up to 3000 mg/kg) or rats (up to 1500 mg/kg).

No adverse fetal effects in mice (up to 3000 mg/kg) or rats (up to 1500 mg/kg).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedThe FDA issued a class-wide warning in December 2008 for all antiepileptic drugs, including gabapentin, regarding increased risk of suicidal ideation and behavior[37]model confidence 100%
Verified

Abstract explicitly confirms FDA December 2008 warning for all AEDs with increased suicidal ideation/behavior, with gabapentin specifically named.

FDA December 2008 warning: all AEDs associated with increased suicidal ideation/behavior. Gabapentin specifically named.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveThe magnitude of risk specific to gabapentin is debated, and some analyses question the applicability of the class-wide designation to gabapentin specifically.[38]model confidence 60%
Inconclusive

Abstract discusses whether newer ASMs carry similar suicidality risk as the FDA class-wide warning implies, but does not specifically question gabapentin's inclusion or name it as debated.

Meta-analysis examining whether newer ASMs carry similar suicidality risk.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedTolerance: Animal data demonstrate that repeated gabapentin administration produces α2δ-1 subunit downregulation in thalamus and spinal dorsal horn, directly reducing the drug's own target density[11]model confidence 100%
Verified

Abstract confirms α2δ-1 downregulation in thalamus/spinal dorsal horn associated with gabapentin insensitivity in rat model after repeated administration.

α2δ-1 down-regulation in thalamus/spinal dorsal horn associated with GBP insensitivity after repeated administration in rat model.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPhysical dependence: Documented with prolonged use, characterized by a withdrawal syndrome on abrupt discontinuation[3]model confidence 95%
Verified

Abstract confirms three case reports of withdrawal symptoms after abrupt discontinuation and recommends tapering, documenting the withdrawal syndrome.

Three case reports of withdrawal symptoms after abrupt gabapentin discontinuation. Recommends tapering, especially at high doses.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPhysical dependence: Documented with prolonged use, characterized by a withdrawal syndrome on abrupt discontinuation[39]model confidence 90%
Verified

Abstract is a review of case reports on gabapentin abuse, dependence, and withdrawal, directly supporting the claim that physical dependence and withdrawal syndrome are documented.

Review of case reports on gabapentin abuse, dependence, and withdrawal.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedOnly 4 published cases of behavioral dependence on gabapentinoids without prior substance use disorder history have been identified — all involving pregabalin, none gabapentin[41]model confidence 100%
Verified

Abstract explicitly states only 4 cases of behavioral dependence without prior SUD, all pregabalin, directly supporting this claim.

Found only 4 cases of behavioral dependence without prior SUD; all pregabalin.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedIn populations with opioid use disorder, gabapentin misuse prevalence reaches approximately 26%, compared with 4% in non-OUD populations.[10]model confidence 100%
Verified

Abstract explicitly reports 26% misuse in OUD populations vs 4% in non-OUD populations (p<0.0001).

26% of patients with OUD reported gabapentin misuse vs 4% without OUD (p<0.0001).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedGradual taper is recommended; one severe case required an 18-month taper.[40]model confidence 100%
Verified

Abstract directly describes a case requiring an 18-month slow taper using BRAVO Protocol for severe gabapentin dependence.

32-year-old female... developed severe dependence and withdrawal requiring 18-month slow taper using BRAVO Protocol.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedPopulation-level data confirm that gabapentin co-prescription with opioids significantly increases opioid-related mortality[5]model confidence 100%
Verified

Abstract directly confirms population-based nested case-control study showing co-prescription with opioids significantly increases opioid-related death.

Population-based nested case-control study: co-prescription of gabapentin with opioids significantly increases risk of opioid-related death.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedAmong heroin users, gabapentinoid polydrug use substantially increases overdose risk[35]model confidence 100%
Verified

Abstract explicitly states gabapentinoids potentiate heroin effects and increase overdose risk.

Gabapentinoids potentiate heroin effects and increase overdose risk.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveForensic data show gabapentin present in 26% of mixed-drug fatalities, invariably alongside opioids.[34]model confidence 60%
Inconclusive

Abstract confirms 100% opioid co-occurrence (supporting 'invariably') in n=46 gabapentin-present cases, but the 26% prevalence figure (of total fatalities) is not stated in the abstract.

Gabapentin present in 100% of cases where it appeared in mixed drug fatalities (n=46), an opiate was also present.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedNo pharmacokinetic interaction occurs — gabapentin does not affect CYP3A4 (the primary metabolic pathway for most benzodiazepines)[17]model confidence 90%
Verified

Abstract confirms gabapentin lacks significant CYP enzyme inducing/inhibiting properties in humans, which encompasses CYP3A4.

Gabapentin, vigabatrin, and levetiracetam are devoid of significant CYP enzyme inducing or inhibiting properties in humans.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveGabapentin is used therapeutically for alcohol withdrawal, but concurrent recreational alcohol co-use amplifies sedation and respiratory depression risk.[23]model confidence 50%
Inconclusive

Abstract supports therapeutic use for alcohol withdrawal but does not address the specific risk of concurrent recreational alcohol co-use amplifying sedation or respiratory depression.

Gabapentin reduces alcohol withdrawal severity and percentage of heavy drinking days.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveGabapentin is used therapeutically for alcohol withdrawal, but concurrent recreational alcohol co-use amplifies sedation and respiratory depression risk.[30]model confidence 50%
Inconclusive

Abstract confirms gabapentin use for alcohol withdrawal and early abstinence, but does not address risks of concurrent recreational alcohol co-use with gabapentin.

Review of gabapentin for AUD; mild alcohol withdrawal and early abstinence. Well-tolerated but concern about abuse potential.

checked by claude-sonnet-4-6 · Apr 28, 2026

inconclusiveIts lack of CYP involvement and negligible protein binding eliminate the two most common mechanisms of pharmacokinetic drug interactions.[17]model confidence 60%
Inconclusive

Abstract confirms no CYP involvement but does not address negligible protein binding. Only half the compound claim is verifiable from this abstract.

Gabapentin, vigabatrin, and levetiracetam are devoid of significant CYP enzyme inducing or inhibiting properties in humans.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedOpioid co-use: Contraindicated or requires strict clinical supervision due to compounded respiratory depression risk.[5]model confidence 85%
Verified

Abstract demonstrates significantly increased opioid-related mortality with co-prescription, which directly supports clinical guidance to avoid or strictly supervise this combination.

Co-prescription of gabapentin with opioids significantly increases risk of opioid-related death.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedOpioid co-use: Contraindicated or requires strict clinical supervision due to compounded respiratory depression risk.[35]model confidence 85%
Verified

Abstract confirms gabapentinoids potentiate heroin effects and increase overdose risk, supporting the need for clinical supervision or avoiding co-use.

Gabapentinoids potentiate heroin effects and increase overdose risk.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedRenal impairment: Dose reduction is mandatory, as gabapentin clearance is directly proportional to creatinine clearance[19]model confidence 100%
Verified

Abstract directly states gabapentin clearance is proportional to CrCL and dosing adjustments are required for renal impairment.

Gabapentin cleared via renal excretion proportional to creatinine clearance (CrCL). Dosing adjustments required for renal impairment.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedHistory of substance use disorder: Elevated misuse risk, particularly in individuals with opioid use disorder (26% misuse prevalence vs 4% in non-OUD populations)[10]model confidence 100%
Verified

Abstract explicitly reports 26% gabapentin misuse in OUD vs 4% non-OUD, directly supporting the claim.

26% of patients with OUD reported gabapentin misuse vs 4% without OUD (p<0.0001).

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSuicidal ideation: Per the FDA class-wide antiepileptic drug warning, patients with depression or suicidal ideation require monitoring during gabapentin therapy.[37]model confidence 90%
Verified

Abstract confirms FDA December 2008 class-wide AED warning including gabapentin for suicidal ideation/behavior, supporting the recommendation for monitoring.

FDA December 2008 warning: all AEDs associated with increased suicidal ideation/behavior. Gabapentin specifically named.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedAnimal studies show no teratogenicity at moderate doses, but maternal toxicity occurred at high doses in rabbits[36]model confidence 100%
Verified

Abstract confirms no adverse fetal effects in mice and rats, and maternal toxicity with one death and four abortions in rabbits at 1500 mg/kg.

No adverse fetal effects in mice (up to 3000 mg/kg) or rats (up to 1500 mg/kg). Rabbits at 1500 mg/kg: maternal toxicity, one death, four aborted.

checked by claude-sonnet-4-6 · Apr 28, 2026

comparative pharmacology2 claims2verified
verifiedOnly 4 published cases of behavioral dependence on gabapentinoids without prior substance use disorder history have been identified — all involving pregabalin, none gabapentin[41]model confidence 100%
Verified

Abstract explicitly states only 4 cases of behavioral dependence without prior SUD were found, all pregabalin.

Found only 4 cases of behavioral dependence without prior SUD; all pregabalin.

checked by claude-sonnet-4-6 · Apr 28, 2026

verifiedSource: .[6]model confidence 70%
Verified

The cited PK comparison paper is a valid source for gabapentin vs pregabalin pharmacokinetic comparisons in this section.

A comparison of the pharmacokinetics and pharmacodynamics of pregabalin and gabapentin.

checked by claude-sonnet-4-6 · Apr 28, 2026

legal status1 claim1verified
verifiedThis patchwork reflects an ongoing tension between gabapentin's clinical utility as a non-opioid analgesic and mounting pharmacovigilance signals of misuse-related harm.[42]model confidence 80%
Verified

Abstract is a pharmacovigilance analysis specifically examining gabapentin misuse signals via FDA AERS, directly supporting the 'mounting pharmacovigilance signals of misuse-related harm' component of the claim.

Pharmacovigilance analysis using FDA AERS for gabapentin misuse signals.

checked by claude-sonnet-4-6 · Apr 28, 2026

05

Coverage & Gaps

effect links
60 links · 60 approved · 21 audited0/60 with evidence basis
06

Research Trail

substance-article pipeline-v5 Apr 28, 2026

StepSourceQueryResults
1database lookupPubChemgabapentin1 result, 1 selected
selection rationale

Primary chemical identity verification

2literature searchPubMedgabapentin mechanism of action alpha-2-delta calcium channel pharmacology10 results, 4 selected
selection rationale

Core pharmacology papers

3literature searchPubMedgabapentin pharmacokinetics bioavailability absorption human10 results, 3 selected
selection rationale

Key human PK data

4literature searchOpenAlexgabapentin mechanism alpha-2-delta calcium channel10 results, 2 selected
selection rationale

Highly-cited mechanistic paper

5literature searchPubMedgabapentin dependence withdrawal syndrome abuse misuse7 results, 4 selected
selection rationale

Dependence and withdrawal evidence

6literature searchPubMedgabapentin overdose toxicity death case report2 results, 1 selected
selection rationale

Sole case of gabapentin-only fatality

7literature searchPubMedgabapentin postherpetic neuralgia randomized controlled trial efficacy8 results, 3 selected
selection rationale

Systematic review evidence for efficacy

8literature searchPubMedgabapentin opioid interaction respiratory depression overdose death3 results, 3 selected
selection rationale

Critical interaction/safety data

9literature searchPubMedgabapentin tolerance analgesic anticonvulsant mechanism cellular8 results, 1 selected
selection rationale

Tolerance mechanism paper

10clinical trial searchClinicalTrials.govgabapentin pain anxiety epilepsy3 results, 1 selected
selection rationale

Selected completed phase 4 trial

11literature searchPubMedgabapentin Cochrane review postherpetic neuralgia diabetic neuropathy8 results, 2 selected
selection rationale

Highest-quality systematic review evidence

12literature searchPubMedgabapentin opioid interaction respiratory depression overdose death3 results, 3 selected
selection rationale

Critical safety/interaction papers

13literature searchPubMedgabapentin withdrawal symptoms discontinuation syndrome2 results, 2 selected
selection rationale

Withdrawal documentation

14literature searchPubMedgabapentin pregabalin comparison pharmacokinetics2 results, 1 selected
selection rationale

Definitive PK comparison study

15web searchWebSearchgabapentin legal status scheduling UK USA controlled substance history10 results, 2 selected
selection rationale

Legal status data not in academic databases

16web searchWebSearchgabapentin Satzinger discovery synthesis 1975 Parke-Davis FDA approval 199310 results, 1 selected
selection rationale

Historical data not in modern academic databases

17document retrievalPubMedPMID 86214441 result, 1 selected
selection rationale

Seminal pharmacology discovery

18document retrievalPubMedPMID 76009091 result, 1 selected
selection rationale

Fundamental PK data

19web searchWebSearchgabapentin LD50 lethal dose animal mouse rat toxicity DrugBank FDA10 results, 1 selected
selection rationale

Toxicity data not separately published

20web searchWebSearchgabapentin scheduling Australia Canada legal status10 results, 1 selected
selection rationale

Legal status in additional jurisdictions

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

## Chemical Identity

**Verified against PubChem CID 3446 (api_verified)**

| Property | Value |
|---|---|
| IUPAC name | 2-[1-(aminomethyl)cyclohexyl]acetic acid |
| Systematic name (brief) | 2-[1-(aminomethyl)cyclohexyl]acetic acid ✓ Match |
| Molecular formula | C9H17NO2 |
| Molecular weight | 171.24 g/mol |
| SMILES | NCC1(CC(=O)O)CCCCC1 |
| InChIKey | UGJMXCAKCUNAIE-UHFFFAOYSA-N |
| CAS number | 60142-96-3 |
| PubChem CID | 3446 |

**Brief seed data gaps now filled:** The brief was missing SMILES, molecular formula, molecular weight, InChIKey, and PubChem CID — all now confirmed from PubChem.

**Physical properties (web-retrieved):** Gabapentin is a white crystalline solid that exists as a zwitterion at physiological pH (–NH3+ and –COO– charged groups). Melting point 162–166°C (438 K). Highly water soluble. Three known anhydrous polymorphs (α, β, γ); the α form is the most thermodynamically stable due to densest molecular packing. Crystal structures stabilized by dense hydrogen-bond networks between NH3+ and COO– groups [Ref 47].

**Stereochemistry:** Gabapentin is achiral — the cyclohexyl scaffold is symmetric. No active enantiomers. The aminomethyl group preferentially occupies the axial position in the crystalline zwitterionic form [Ref 47].

---

## Pharmacology

### Primary Target: α2δ Voltage-Gated Calcium Channel Subunit

Gabapentin's primary and definitively confirmed pharmacological target is the **α2δ-1 subunit** (and to a lesser extent α2δ-2) of high-voltage-activated calcium channels (CaV1s and CaV2s). Despite its structural resemblance to GABA, gabapentin does NOT bind to GABA-A or GABA-B receptors, GABA transporters, or GABA transaminase (Gee et al. 1996 [Ref 35]).

**Discovery of binding target:** Gee et al. (1996) [Ref 35] were the first to isolate and characterize the [³H]gabapentin-binding protein from pig cerebral cortex, identifying it as the α2δ subunit of L-type voltage-dependent Ca²⁺ channels. The protein was purified 1022-fold; its partial N-terminal sequence was identical to the α2δ subunit of rabbit skeletal muscle L-type Ca²⁺ channel. [³H]Gabapentin was described as "the first pharmacological agent described that interacts with an α2δ subunit of a voltage-dependent Ca²⁺ channel." This landmark 1996 paper established the entire mechanistic framework for gabapentinoid pharmacology.

Brown et al. (1998) [Ref 36] further confirmed this by developing a refined radioligand binding assay using [³H]leucine, demonstrating the high-affinity interaction of gabapentin with the purified α2δ subunit from porcine brain.

**Structural binding basis:** Chen, Mondal & Minor (2023) [Ref 1] published the cryo-EM structure of gabapentin bound to the brain/cardiac CaV1.2/CaVβ3/CaVα2δ-1 channel complex. The structure reveals a binding pocket in the **dCache1 domain** of CaVα2δ-1 that completely encapsulates gabapentin. Isoform sequence variations in the dCache1 domain explain gabapentin's selectivity for α2δ-1 and α2δ-2 over α2δ-3 and α2δ-4 (which do not bind gabapentin) (Page et al. 2023 [Ref cited in pharmacology]).

**Calcium channel inhibition IC50:** Sutton et al. (2002) [Ref 24] demonstrated that gabapentin potently inhibits whole-cell Ca²⁺ channel current (IBa) in rat dorsal root ganglion neurons with an estimated **IC50 of 167 nM**. Inhibition was reduced by L-isoleucine (competitive neutral amino acid) but not by GABAB antagonist saclofen, confirming direct α2δ subunit action. The gabapentin-sensitive current showed mixed pharmacology (N-, L-, and P/Q-type), dominated by N-type.

**Neuropathic pain mechanism:** In spinal nerve-ligation rat models, peripheral nerve injury causes **>17-fold upregulation** of α2δ-1 subunit expression in dorsal root ganglia ipsilateral to injury, and this upregulation precedes allodynia onset (Luo et al. 2001 [Ref 28]). Gabapentin/pregabalin then inhibit anterograde trafficking of α2δ-1 to presynaptic terminals (Bauer et al. 2009 [Ref 23]), reducing neurotransmitter release and spinal sensitization. Down-regulation of α2δ-1 via neuronal loss in later-stage injury is associated with gabapentinoid insensitivity/tolerance (Yang et al. 2016 [Ref 17]).

**Mechanistic summary (Patel & Dickenson 2016 [Ref 26]):** Gabapentinoids bind α2δ-1 and α2δ-2 subunits; only α2δ-1 is implicated in neuropathy development. Effects are neuron-type-specific in spinal cord and higher centers. NNT (number needed to treat) averages 3–8 across neuropathy indications.

**What gabapentin does NOT do:**
- Does not directly open or block voltage-gated sodium channels
- Does not interact with GABA-A or GABA-B receptors
- Does not inhibit GABA uptake/metabolism
- Not hepatically metabolized; no CYP involvement (Benedetti 2000 [Ref 25])

---

### Pharmacokinetics (Human)

**Absorption:** Gabapentin is absorbed via the system L (large neutral amino acid) transporter in the small intestine — a saturable, carrier-mediated mechanism. This makes absorption **dose-dependent and nonlinear (zero-order process)**. Unlike pregabalin (linear, >90% bioavailability at any dose), gabapentin bioavailability decreases as dose increases (Bockbrader et al. 2010 [Ref 21]):

| Dose Range (daily) | Approximate Bioavailability |
|---|---|
| 300 mg single dose | ~68.8% |
| 400 mg single dose | ~62.7% |
| 800 mg single dose | ~47.1% |
| 900 mg/day | ~60% |
| 3600 mg/day | ~33% |

Sources: Tran et al. 2017 [Ref 4]; Bockbrader et al. 2010 [Ref 21].

High interindividual variability in bioavailability is well documented; genetic polymorphisms in ABCB1 (2677G>T/A) significantly influence absorption rate constant (Tran et al. 2017 [Ref 4]).

**Tmax:** 3–4 hours after oral administration (Bockbrader et al. 2010 [Ref 21]). One-compartment model fit, with lag time ~0.311h (Tran et al. 2017 [Ref 4]).

**Plasma protein binding:** <3% (Radulovic et al. 1995 [Ref 37]; Bockbrader et al. 2010 [Ref 21])

**Volume of distribution:** ~81 L in healthy subjects (Tran et al. 2017 [Ref 4])

**Elimination half-life:** Approximately **5–7 hours** (population studies range 1.7h in rats to ~6h in humans; Bockbrader et al. 2010 [Ref 21]; Radulovic et al. 1995 [Ref 37]).

**Metabolism:** Gabapentin is **not significantly metabolized** in humans. It is excreted almost entirely unchanged in urine. In dogs, N-methylgabapentin accounts for ~34% of dose, but in mice, rats, monkeys, and humans, metabolism is minimal (<5%) (Radulovic et al. 1995 [Ref 37]).

**CYP interactions:** Gabapentin does not induce or inhibit any of the major human hepatic CYP isoenzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4) (Benedetti 2000 [Ref 25]). This profile results in very few pharmacokinetic drug–drug interactions.

**Renal excretion:** Elimination is directly proportional to creatinine clearance (CrCL). Dosing reduction is required in renal impairment (Lal et al. 2012 [Ref 39]; Ahmed et al. 2017 [Ref 5]).

**Food effects:** Can be given without regard to meals; food slightly increases absorption from floating gastric-retention formulations but does not meaningfully affect standard immediate-release tablets (Bockbrader et al. 2010 [Ref 21]).

**Elderly patients:** Oral clearance in elderly nursing home patients 2.93 L/h, lower than general population due to reduced renal function. Dose-dependent bioavailability confirmed across age groups (Ahmed et al. 2017 [Ref 5]).

---

## History

**Synthesis:** Gabapentin was first synthesized in **1974–1975** and first described in a patent in 1975, by **Gerhart Satzinger** and **Hartenstein** at **Goedecke AG** in Freiburg, Germany — a pharmaceutical subsidiary of Parke-Davis. The compound was designed as a lipophilic, cyclic analog of γ-aminobutyric acid (GABA) intended to cross the blood–brain barrier more readily than GABA itself [Ref 29]. Early pharmacology studies in mice showed sedating properties and prevention of thiosemicarbazide-induced seizures.

**Binding mechanism discovered:** Gee et al. published the landmark paper identifying α2δ as the gabapentin binding site in **1996** [Ref 35] — a full two decades after synthesis, illustrating how long gabapentin's actual mechanism remained unknown.

**FDA approval and launch:**
- UK first approved: **1993**
- FDA approved for partial seizures (adjunctive, adults): **December 31, 1993**
- US market launch as Neurontin (Parke-Davis): **February 1994**
- FDA approved for **postherpetic neuralgia**: **2002**
- FDA approved for **restless legs syndrome** (gabapentin enacarbil extended-release): **2011**

**Off-label marketing scandal:** Parke-Davis (acquired by Pfizer 2000) was found to have aggressively and illegally promoted Neurontin for off-label uses including pain, bipolar disorder, anxiety, and migraine. A major whistleblower lawsuit resulted in a **$430 million settlement in 2004** — one of the largest pharmaceutical fraud settlements at the time. The off-label promotion significantly expanded prescribing and contributed to eventual misuse concerns.

**Generic availability:** Gabapentin became available as a generic in the US in 2004 when Neurontin's patent expired.

**Regulatory reclassification (misuse era):** Beginning with Kentucky in July 2017, a wave of US state-level scheduling began. The UK reclassified gabapentin as Class C Schedule 3 in **April 2019** in response to mounting evidence of misuse and associated deaths. By 2024, 8 US states had classified gabapentin as Schedule V and 17 required PDMP reporting (Comprehensive Analysis 2016–2024 [Ref 31]).

---

## Subjective Effects

No controlled human dosing studies specifically measuring subjective psychoactive effects (e.g., using standardized rating scales) were identified. The following is drawn from adverse event data in clinical trials, case reports, qualitative misuse literature, and observational data.

**At therapeutic doses (standard clinical range, 300–1800 mg/day):**
- **Sedation/somnolence** — most commonly reported CNS adverse effect in epilepsy and pain trials (Brown & Wright 2009 [Ref 32])
- **Dizziness** — reported in a majority of patients in clinical trials; dose-dependent
- **Ataxia** — dose-dependent motor incoordination
- **Fatigue**
- **Nystagmus**
- **Peripheral edema** — common, particularly in lower extremities
- **Weight gain** — documented with prolonged use
- **Anxiolytic effects** — gabapentin reduces anxiety in clinical populations; used off-label for GAD and social phobia (Van Ameringen et al. 2004 [Ref 41]; Garakani et al. 2020 [Ref 48])
- **Pain suppression** — primary therapeutic effect in neuropathic pain and PHN

**At higher doses / recreational use context:**
- Euphoria reported, particularly in individuals with opioid use disorder (Bastiaens et al. 2016 [Ref 27])
- Potentiation of opioid effects — users report gabapentin substantially amplifies heroin and prescription opioid effects (Lyndon et al. 2017 [Ref 15])
- Tactile euphoria and feelings of bodily lightness reported in user accounts
- Cognitive slowing, memory impairment, depersonalization at high doses
- Emotional blunting and emotional suppression reported
- Anxiolytic effects at recreational doses mirror clinical anxiolytic use
- Sexual arousal suppression reported (consistent with broad CNS depressant effects)

**Qualitative misuse literature (McNeilage et al. 2024 [Ref 34]):** Systematic review of qualitative studies found experiences of euphoria, enhanced sociability, anxiolysis, sedation, and opioid-potentiation as reported motives for misuse. Physical dependence symptoms widely reported.

**Effects taxonomy confirmation:** The seed data effects taxonomy (sedation, pain suppression, muscle relaxation, tactile euphoria, dizziness, motor control impairment, cognitive euphoria, anxiety suppression, amnesia, thought deceleration, emotional suppression, depersonalization, suicidal ideation [FDA warning], internal hallucinations/dreaming enhancement at higher doses) is **broadly consistent** with available literature. No major contradictions found.

**⚠️ Flag:** No published controlled human dosing studies with standardized psychoactive rating instruments (ARCI, POMS, DEQ, etc.) were found that directly characterize gabapentin's subjective dose–response profile in non-clinical populations. Euphoria, tactile effects, and mood data are derived from misuse literature and adverse event reports, not from controlled experiments.

---

## Safety & Toxicity

### Acute Toxicity
- **LD50:** Not established in mice or rats at doses up to **8,000 mg/kg** orally. This represents an extremely wide safety margin relative to human therapeutic doses (typically 300–3,600 mg/day) [Ref 40].
- **Acute overdose:** Gabapentin overdose symptoms include somnolence, dizziness, double vision, slurred speech, drowsiness, ataxia, lethargy, and mild CNS depression. These are generally reversible.
- **First reported fatality from gabapentin alone:** Middleton (2011) [Ref 11] described a 62-year-old woman with depression whose death was attributed to intentional gabapentin ingestion; postmortem peripheral blood concentration was **88 µg/mL** (approximately 4–44× the therapeutic range of 2–20 µg/mL). This remains among very few reported sole-gabapentin fatalities.
- **Forensic data:** Finlayson et al. (2017) [Ref 16] found gabapentin present in 46/180 (26%) mixed drug fatalities in Michigan, always co-occurring with opioids. Average serum gabapentin 13.56 µg/mL (range 0.5–88.7 µg/mL) — mostly within the therapeutic range, suggesting synergistic rather than direct toxicity.

### Interaction-Related Toxicity (CRITICAL)
- **Opioid co-use:** Gomes et al. (2017) [Ref 14] published a population-based nested case-control study finding that co-prescription of gabapentin with opioids **significantly increases risk of accidental opioid-related death**. This is the most important safety concern.
- **Heroin users:** Lyndon et al. (2017) [Ref 15] demonstrated that gabapentinoid use by heroin users substantially increases overdose risk, likely via potentiation of respiratory depression.
- **CNS depressants (benzodiazepines, alcohol):** Additive pharmacodynamic CNS/respiratory depression. No specific pharmacokinetic interaction (gabapentin does not affect CYP enzymes), but the pharmacodynamic combination is dangerous. Alprazolam+gabapentin caution noted in the brief is consistent with additive CNS depression.

### Chronic Toxicity
- **Carcinogenicity:** No evidence in mice at doses up to 2,000 mg/kg/day in 2-year studies [Ref 40]
- **Organ toxicity:** Generally classified as low chronic toxicity. Peripheral edema and weight gain are well-documented with long-term use.

### Developmental/Reproductive Toxicity
- No adverse fetal effects in mice (up to 3,000 mg/kg) or rats (up to 1,500 mg/kg) (Petrere & Anderson 1994 [Ref 38])
- In rabbits at 1,500 mg/kg: maternal toxicity with one death and four abortions; minor visceral variation in rat fetuses at 1,500 mg/kg not considered biologically significant [Ref 38]
- Limited human pregnancy registry data for newer antiepileptics; cautious use in pregnancy recommended [Ref cited in context of AED teratogenicity]

### Psychiatric Safety
- **Suicidal ideation:** The FDA issued a class-wide warning in December 2008 for all antiepileptic drugs (including gabapentin) for increased risk of suicidal ideation and behavior, based on a pooled meta-analysis of placebo-controlled trials (Kanner 2011 [Ref 45]). The magnitude of risk is debated and some studies contest the class-wide designation for gabapentin specifically (Siamouli et al. 2014).
- This is the basis for "suicidal ideation" in the seed data effects taxonomy — **confirmed** as an FDA-recognized adverse effect.

---

## Harm Reduction

### Contraindications and High-Risk Populations
- **Opioid users:** Contraindication or strict caution for co-use with opioids due to compounded respiratory depression risk [Ref 14, 15]
- **Benzodiazepine users:** Additive CNS depression; caution warranted
- **Renal impairment:** Dose reduction mandatory; clearance tracks creatinine clearance [Ref 39]
- **History of substance use disorder:** Elevated misuse risk; 26% of OUD patients report gabapentin misuse vs. 4% of non-OUD patients [Ref 27]

### Tapering/Discontinuation
- Abrupt discontinuation, especially at high doses or after prolonged use, risks withdrawal syndrome (Norton 2001 [Ref 22])
- Slow taper recommended; one severe case required an **18-month taper** (Deng et al. 2021 [Ref 10])
- Taper rate should be individualized; BRAVO Protocol provides a framework [Ref 10]

### Testing and Identification
- Gabapentin is not detected by standard immunoassay urine drug screens — requires specific HPLC or LC-MS/MS testing
- This is clinically significant: missed in standard toxicological screens, contributing to under-recognition in overdose settings

### Emergency Response
- Gabapentin overdose: supportive care; hemodialysis effective for gabapentin removal (renally cleared, low protein binding)
- Mixed overdose with opioids: naloxone for opioid reversal; supportive respiratory management

---

## Tolerance & Dependence

### Tolerance
- **Mechanism:** Yang et al. (2016) [Ref 17] demonstrated in rats that α2δ-1 subunit **down-regulation** in thalamus and spinal dorsal horn is associated with gabapentin insensitivity after repeated administration. This suggests a receptor-level adaptive mechanism in which the drug's own target is reduced by chronic use.
- **Clinical timeline:** The brief states "buildup with prolonged continuous usage" — consistent with the animal literature and clinical observations. No controlled human study was found that formally quantifies the onset rate of clinical tolerance.
- **⚠️ Flag:** The tolerance timeline in the brief (full reset 10.5 days) was not confirmed in published clinical literature. This appears to be based on clinical estimation. No controlled human study quantifying the gabapentin tolerance reset period was identified. Editorial review recommended.

### Dependence
- **Physical dependence:** Documented with prolonged use; characterized by a withdrawal syndrome on abrupt discontinuation (Norton 2001 [Ref 22]; Mersfelder & Nichols 2016 [Ref 7])
- **Withdrawal symptoms:** Anxiety, insomnia, nausea, diaphoresis, tremor, agitation, palpitations, hypertension; seizures reported in some cases. Symptom onset typically within 12–48 hours of abrupt discontinuation.
- **Behavioral dependence (addiction):** Very low addictive potential in general population. Bonnet et al. (2018) [Ref 8] found only 4 published cases of behavioral dependence on gabapentinoids without prior SUD history — all for pregabalin, none for gabapentin. Authors concluded gabapentinoids (especially gabapentin) have "quite rarely addictive" potential in the general population.
- **Risk in SUD populations:** Misuse strongly associated with opioid use disorder (Bastiaens et al. 2016 [Ref 27]; Evoy et al. 2021 [Ref 2]). In OUD populations, gabapentin may be sought for opioid augmentation or self-medication of withdrawal.
- **Qualitative experiences:** McNeilage et al. 2024 [Ref 34] systematic review of lived experiences documented physical dependence symptoms consistent with above clinical reports.

### Cross-tolerance
- No published data found on gabapentin cross-tolerance with other drug classes. Structural analog pregabalin is expected to share cross-tolerance given identical binding target (α2δ-1).

---

## Interactions

### Opioids (CRITICAL — SAFETY-CRITICAL INTERACTION)
- **Pharmacodynamic:** Additive/synergistic CNS and respiratory depression
- **Mortality risk:** Gomes et al. (2017) [Ref 14] — population-based study confirming gabapentin co-prescription with opioids significantly increases opioid-related death risk
- **Heroin:** Lyndon et al. (2017) [Ref 15] — gabapentinoid use by heroin users substantially increases overdose risk
- **Forensic:** Gabapentin found in 26% of mixed drug fatalities, always co-occurring with opioids (Finlayson et al. 2017 [Ref 16])
- **Seed data interaction flag:** Brief lists "Alprazolam: caution" — this is consistent with literature on additive CNS depression with all benzodiazepines. No specific published pharmacokinetic interaction study for the gabapentin+alprazolam pair was found; the interaction is pharmacodynamic (additive CNS depression), not pharmacokinetic.

### Benzodiazepines / CNS Depressants (including Alprazolam)
- **Mechanism:** Pharmacodynamic additive CNS depression (sedation, respiratory depression, cognitive impairment)
- **No CYP interaction:** Gabapentin does not affect CYP enzymes [Ref 25]; therefore no pharmacokinetic interaction with alprazolam (CYP3A4 substrate)
- **Risk level:** Caution is appropriate, especially at higher doses of either agent

### Alcohol
- Additive CNS depression
- Gabapentin is used therapeutically for alcohol withdrawal [Ref 42, 49], but concurrent recreational co-use with alcohol amplifies sedation and depression risks

### No significant interactions with:
- Anti-epileptic drugs (no CYP induction/inhibition)
- Oral contraceptives (confirmed: no enzyme induction)
- Protein-bound drugs (minimal plasma protein binding eliminates displacement interactions)

---

## Legal Status

### United States
- **Federal status:** NOT a controlled substance under the Controlled Substances Act. No DEA scheduling at federal level.
- **State-level:** As of 2024, across 51 jurisdictions: 8 (16%) classified gabapentin as **Schedule V** controlled substance; 17 (33%) require PDMP reporting without scheduling (Comprehensive Analysis 2016–2024 [Ref 31])
- **First state to schedule:** Kentucky, July 2017. Followed by West Virginia and Tennessee in 2018. Most scheduling occurred 2017–2019, concentrated in Appalachian and Eastern Midwest regions [Ref 31]
- **Pharmacovigilance signal:** FDA AERS data confirm misuse signals (Vickers-Smith et al. 2020 [Ref 9])

### United Kingdom
- **Status:** **Class C, Schedule 3 controlled drug** — reclassified effective **April 2019** [Ref 30]
- Does not require CD cabinet storage or CD register entry
- Prescription required; electronic prescribing permitted

### Canada
- **Status:** NOT controlled under federal Controlled Drugs and Substances Act (CDSA)
- Regulated as prescription drug under Food and Drug Regulations
- Some provinces monitor via prescription tracking programs

### Australia
- **Status:** Listed in Appendix D of the Poisons Standard as a "prescribed restricted substance"
- Lighter regulation than pregabalin

### European Union
- Prescription-only throughout EU member states
- Scheduling varies by country; some have placed stricter controls following UK precedent

---

## Clinical Trials

### FDA-Approved Indications (with trial evidence basis)
1. **Partial-onset seizures (adjunctive):** Pivotal trials in 1990s; efficacy established across multiple Phase 3 RCTs (Slater et al. 2018 meta-analysis [Ref cited])
2. **Postherpetic neuralgia:** Cochrane systematic review (Wiffen et al. 2017 [Ref 12]) confirms ≥50% pain relief vs placebo: RR 1.8 [95% CI 1.5–2.1] in PHN; RR 1.9 [95% CI 1.5–2.3] in painful diabetic neuropathy at ≥1,200 mg/day
3. **Restless legs syndrome:** Via gabapentin enacarbil extended-release (Horizant); gabapentin itself not FDA-approved for this indication

### Notable Clinical Trials from Registry
- **NCT03635905:** Gabapentin for pain management during dilation and evacuation (D&E). Phase 4, completed. Sponsor: Medstar Health Research Institute.
- **NCT03708237:** Gabapentin vs ropinirole for RLS in hemodialysis patients. Phase 2, terminated.

### Key Evidence Summaries
- **Neuropathic pain (Cochrane 2017 [Ref 12]):** Highest-quality evidence; substantial benefit for PHN and PDN at ≥1,200 mg/day. 14 of 16 meta-analyses reviewed by de Freminville et al. (2026 [Ref 19]) rated "critically low" quality by AMSTAR 2; Cochrane review rated highest.
- **Perioperative pain (Zhai et al. 2016 [Ref 46]):** Meta-analysis (6 studies, 769 patients) shows gabapentin reduces VAS pain scores at 24h and 48h post-TKA, and reduces morphine consumption (MD −8.28 mg at 24h)
- **Alcohol use disorder (Andrade 2020 [Ref 42]):** Meta-analyses show small but significant reduction in alcohol withdrawal severity; large RCT found extended-release gabapentin enacarbil ineffective for AUD; current evidence supports only second-line use
- **Epilepsy vs pregabalin (French et al. 2016 [Ref 33]):** Comparative trial; prestudy modeling predicted pregabalin superiority, confirmed clinically

---

## Community Feedback Analysis

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

---

## Gaps & Flags

### Data Not Found in Published Literature
1. **⚠️ SAFETY-CRITICAL FLAG — Alprazolam interaction mechanism:** The brief lists "Alprazolam: caution" as a known interaction. Published literature confirms pharmacodynamic additive CNS depression with benzodiazepines as a class, but NO specific pharmacokinetic or pharmacodynamic interaction study for gabapentin+alprazolam specifically was found. The "caution" severity designation is appropriate but based on class-level reasoning. Generation agent should note this is pharmacodynamic, not pharmacokinetic, and not alprazolam-specific.

2. **⚠️ SAFETY-CRITICAL FLAG — Tolerance reset timeline:** The brief states tolerance full reset is 10.5 days. No published human clinical study was found confirming this specific value. Yang et al. (2016) [Ref 17] shows α2δ-1 down-regulation in animals; no controlled human study of tolerance reversal timeline was identified. This value should be flagged for editorial review.

3. **No controlled subjective effects studies:** No human laboratory studies using standardized rating scales (ARCI, DEQ, etc.) were found measuring gabapentin's subjective dose–response in non-patient populations. All subjective effect data are from adverse event reports, misuse literature, and qualitative accounts.

4. **No published Ki values:** Formal radioligand binding Ki at α2δ-1 in purified human protein under standardized conditions was not found in searchable literature. IC50 167 nM from Sutton et al. (2002) [Ref 24] is from rat DRG neurons using whole-cell electrophysiology — closest available.

5. **Limited stereochemistry data relevance:** Gabapentin is achiral; no stereochemical considerations for active isomers.

6. **Gabapentin enacarbil distinction:** Some clinical trials and studies use gabapentin enacarbil (prodrug), which has different PK (linear, 75% F). Generation agent should clearly distinguish these formulations.

### Seed Data Verification Notes
- **SMILES, formula, weight, InChIKey, CAS, PubChem CID:** All confirmed from PubChem [PubChem CID 3446]. Brief was missing all of these — now populated.
- **Characterization "emerging":** Flagged as potentially incorrect. Gabapentin was approved in 1993 and has 30+ years of clinical use. "Established" or "well-characterized" would be more accurate. Recommend editorial review.
- **Chemical class "Gabapentinoid, Amino acid compound":** Confirmed correct. Gabapentin is the namesake compound of the gabapentinoid class.
- **Pharmacological class "Alpha-2-delta voltage-gated calcium channel blocker":** Confirmed correct per Gee 1996 [Ref 35] and Chen 2023 [Ref 1]. "Ligand" is more precise than "blocker" (it modulates trafficking rather than directly blocking the pore), but "blocker" is widely used.
- **Psychoactive class "Depressant, Anxiolytic":** Confirmed.
- **Dose data:** Threshold 200 mg, Light 200–900 mg, Common 900–1500 mg, Strong 1500–2400 mg, Heavy 2400+ mg — these appear consistent with recreational dose reports and clinical data. No published controlled study providing recreational dose-response data was found. Clinical therapeutic doses are typically 300–3,600 mg/day in divided doses. ⚠️ Not independently verified against primary sources for recreational dose thresholds specifically.
- **Duration onset 30–120 min, peak 120–180 min, total 6–10 hours:** Consistent with Tmax data (3–4h) from Bockbrader et al. 2010 [Ref 21]. The 30 min onset lower bound is plausible but not confirmed by published studies. Total duration of 6–10h is consistent with 5–7h half-life.
- **Tolerance full reset 10.5 days:** Not confirmed in published sources. Flag for review.
- **Toxicity "low acute, low chronic":** Confirmed per available data.