This page shows what was measured, who it was measured in, and what that does not settle.
What Gabapentin does in the body
Used for nerve pain after shingles and as added treatment for some seizures.
Despite the name, gabapentin does not act on GABA. It binds a small helper protein attached to the calcium channels on nerve endings. With that helper occupied, fewer channels reach the surface, less calcium enters when the nerve fires, and less of the pain-signalling chemical is released. It damps down an over-firing nerve rather than blocking a pain signal on its way past.
What happened in people
About one in three people with pain after shingles had their pain halved, compared with one in six given a dummy pill.
✓ Reviewed first-read answer
Where this came from
A person wrote this and a reviewer approved it against this exact record. It carries no effect size.
A reviewer approved this against this record. The reviewed-claim record carrying the exact population and effect size does not exist yet.
No source is stored against this line.
The limit that matters most
It has little or no good evidence for ordinary low-back pain.
Where it acts
Presynaptic terminals in dorsal horn and cortex; alpha-2-delta-1 subunit
Kind of result
Symptoms and quality of life
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 6CW7F3G59X · read 2026-08-29
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
The limit a reviewer approved as the one that matters most here.
The four opening statements run to 100 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
Proportion with at least 50% pain intensity reduction or PGIC very much improved
✓ The study showed what it set out to show
Who was studied
Cochrane gabapentin for chronic neuropathic pain (37 studies pooled)
How many people
5914
Study design
Systematic review and meta-analysis
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
Postherpetic neuralgia RR 1.8 (95% CI 1.5 to 2.1), NNT 6.7; painful diabetic neuropathy RR 1.9 (1.5 to 2.3), NNT 5.9
Repeated elsewhere
Replicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. Any adverse event 63% vs 49% (NNH 7.5); adverse event withdrawals 11% vs 8.2% (NNH 30); eight deaths, rated very low quality evidence.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral capsule, tablet and solution; immediate release three times daily
Interval reported. 95% CI 1
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 3 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Gabapentin
What a person takes: Oral capsule, tablet and solution; immediate release three times daily.
The measurement behind this step
Immediate-release gabapentin is dosed three times daily because absorption is saturable and non-linear. Gralise (once-daily gastroretentive) and Horizant (gabapentin enacarbil, a transported prodrug) exist specifically to work around that transporter limit, and they are not interchangeable with each other or with immediate-release gabapentin.
Getting in
Absorbed by a transporter that runs out of capacity
Gabapentin cannot cross the gut wall by itself; it has to hitch a ride on a carrier meant for amino acids. There are only so many carriers, so doubling the dose does not double the amount absorbed.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Absorption is mediated by the large neutral amino acid transporter LAT1 in the small intestine and is saturable, so bioavailability falls as dose rises. This non-linearity is why gabapentin is given three times daily and why the extended-release prodrug gabapentin enacarbil was developed.
Carried across the blood-brain barrier by the same kind of transporter
The same amino acid carriers move it out of the blood into the brain and spinal cord.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
System L amino acid transport carries gabapentin across the blood-brain barrier. It is not metabolised in humans and is eliminated unchanged by the kidney, so dose must be reduced in renal impairment.
It sticks to a helper protein on calcium channels. It has nothing to do with GABA, despite the name.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Binds the alpha-2-delta-1 auxiliary subunit encoded by CACNA2D1. No measurable affinity for GABA-A or GABA-B receptors, no conversion to GABA, and no effect on GABA uptake or metabolism at therapeutic concentrations.
With the helper occupied, fewer calcium gates get delivered to the nerve ending, so less calcium rushes in when the nerve fires and less pain messenger is released.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Alpha-2-delta-1 acts as a trafficking chaperone for pore-forming calcium channel subunits. Gabapentin binding reduces forward trafficking to the presynaptic membrane, lowering depolarisation-evoked calcium influx and reducing release of glutamate, substance P and calcitonin gene-related peptide. The trafficking mechanism operates over days, which fits the clinical observation that effect builds rather than appearing with the first dose.
Pain scores fall in some conditions, and dizziness rises in all of them
In shingles pain and diabetic nerve pain, roughly one extra person in six gets meaningful relief. In back pain, essentially nobody does. The dizziness and drowsiness arrive either way.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Cochrane reports NNT 6.7 for substantial benefit in postherpetic neuralgia and 5.9 in painful diabetic neuropathy, against NNH 7.5 for any adverse event and NNH 30 for withdrawal due to adverse events. Dizziness affected 19%, somnolence 14%, peripheral oedema 7% and gait disturbance 14%.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Licensed for adults with postherpetic neuralgia and for adjunctive seizure control. In practice it is prescribed far more widely — for back pain, sciatica, fibromyalgia, anxiety, alcohol withdrawal and perioperative pain, all off-label.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “Safety and effectiveness of gabapentin in the management of postherpetic neuralgia in pediatric patients have not been established.”
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-30
On older people, the label states: “Clinical studies of gabapentin in epilepsy did not include sufficient numbers of subjects aged 65 and over to determine whether they responded differently from younger subjects.”
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-30
On people who are pregnant, the label states: “Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as gabapentin tablets, during pregnancy.”
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Gabapentin is secreted in human milk following oral administration.”
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-30
On people with reduced kidney function, the label states: “Dosage adjustment in adult patients with compromised renal function is necessary [see Dosage and Administration (2.3) and Clinical Pharmacology (12.3) ].”
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-30
Where the result stopped carrying
Chronic low back pain: no pain benefit and significant harms across every trial that exists
Perioperative analgesia: effects below the minimally important difference at every time point measured
The marketing that created much of the off-label use ended in a guilty plea and a $430 million settlement in 2004
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Prescription only
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Oral capsule, tablet and solution; immediate release three times daily
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
Immediate-release gabapentin is dosed three times daily because absorption is saturable and non-linear. Gralise (once-daily gastroretentive) and Horizant (gabapentin enacarbil, a transported prodrug) exist specifically to work around that transporter limit, and they are not interchangeable with each other or with immediate-release gabapentin.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
The recorded stepping schedule
What follows is the schedule printed on the label, recorded as it is written there. It is a record of what was done, not a recommendation.
US prescribing information · 01b810b7-f4c8-4412-bbc5-b9220d8770d8 · read 2026-08-27
Day 1: single 300 mg dose
US prescribing information · 01b810b7-f4c8-4412-bbc5-b9220d8770d8 · read 2026-08-27
Day 2: 600 mg/day (300 mg two times a day)
US prescribing information · 01b810b7-f4c8-4412-bbc5-b9220d8770d8 · read 2026-08-27
Day 3: 900 mg/day (300 mg three times a day)
US prescribing information · 01b810b7-f4c8-4412-bbc5-b9220d8770d8 · read 2026-08-27
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Commonest adverse effects are dizziness, somnolence, peripheral oedema and gait disturbance. Renal elimination is complete and unchanged, so dose reduction is mandatory in renal impairment and after dialysis. Respiratory depression is a recognised risk when combined with opioids or other CNS depressants and in patients with underlying respiratory compromise. Abrupt withdrawal of an anticonvulsant can precipitate seizures.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Oral capsule, tablet and solution; immediate release three times daily
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Gralise (once-daily gastroretentive) and Horizant (gabapentin enacarbil, a transported prodrug) exist specifically to work around that transporter limit, and they are not interchangeable with each other or with immediate-release gabapentin.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
630 products list this as an active ingredient in the United States drug directory. 630 of them contain it and nothing else.
FDA National Drug Code directory · 71335-3057 · read 2026-08-29
They are sold as capsule, crystal, powder, solution, suspension and tablet, taken oral.
FDA National Drug Code directory · 71335-3057 · read 2026-08-29
The regulator's established pharmacologic class for it is anti-epileptic agent [epc] and decreased central nervous system disorganized electrical activity [pe].
FDA National Drug Code directory · 71335-3057 · read 2026-08-29
409 published labels name it as an active ingredient. 409 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · b6db5ce9-bd4b-420d-88a7-df9d46144c81 · read 2026-08-29
Gabapentin is capsules at 100 mg, 300 mg, and 400 mg, recorded as prescription product; fda label in effect 2024-04-02 in the United States.
US prescribing information · 01b810b7-f4c8-4412-bbc5-b9220d8770d8 · read 2026-08-27
Recorded price in US: 0.02095–0.09004 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 252 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Recorded price in US: 0.08867–0.1712 USD per one millilitre, across 8 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Gabapentin studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That gabapentin acts on the GABA system — it is named for GABA, binds a calcium channel subunit, and has no meaningful GABA receptor activity
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That the volume of gabapentin prescribing reflects the strength of evidence for the indications it is prescribed for
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That an anticonvulsant with proven effect in one neuropathic condition will work in unrelated chronic pain, which is the inference the off-label campaign was built on
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Gabapentin are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
Postherpetic neuralgia: 32% reached substantial pain relief against 17% on placebo
In plain words
In nerve pain after shingles, about a third of people on gabapentin got at least half their pain taken away, against about one in six on a dummy pill. Roughly seven people have to be treated for one to benefit.
What was measured
Proportion achieving at least 50% pain intensity reduction, versus placebo
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Wiffen et al. pooled 37 studies and 5,914 participants. In postherpetic neuralgia at 1,200 mg daily or more: substantial benefit (at least 50% pain relief or PGIC very much improved) in 32% versus 17%, RR 1.8 (95% CI 1.5 to 2.1), NNT 6.7 (5.4 to 8.7), 8 studies, 2,260 participants, moderate-quality evidence. Moderate benefit in 46% versus 25%, NNT 4.8. In painful diabetic neuropathy: substantial benefit 38% versus 21%, RR 1.9 (1.5 to 2.3), NNT 5.9, 6 studies, 1,277 participants.
Written into the record, not signed off as a reviewed claim
Chronic low back pain: no benefit, and a measurable harm profile
In plain words
For the back pain gabapentin is very often prescribed for, pooling every trial that exists found essentially no pain improvement and a clear increase in dizziness, fatigue and thinking problems.
What was measured
Mean difference in pain intensity versus placebo, chronic low back pain
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Shanthanna et al. found eight eligible studies out of 1,385 citations. Gabapentin versus placebo (3 studies, n=185) gave a mean difference of 0.22 pain units, 95% CI -0.5 to 0.07, GRADE very low. Pregabalin versus other analgesics (3 studies, n=332) favoured the comparator, MD 0.42 (0.20 to 0.64). Adverse events versus placebo: dizziness RR 1.99 (1.17 to 3.37), NNH 7; fatigue RR 1.85 (1.12 to 3.05), NNH 8; difficulties with mentation RR 3.34 (1.54 to 7.25), NNH 6; visual disturbance RR 5.72 (1.94 to 16.91), NNH 6. The authors concluded the use of gabapentinoids in chronic low back pain merits caution.
Written into the record, not signed off as a reviewed claim
Warner-Lambert paid $430 million in 2004 for promoting the off-label uses
In plain words
The company that made gabapentin pleaded guilty and paid $430 million for marketing it for conditions it had never been approved for. Internal documents released in that litigation show how the evidence base was shaped.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Department of Justice announced on 13 May 2004 that Warner-Lambert would plead guilty and pay more than $430 million over its Parke-Davis division's promotion of Neurontin for unapproved uses; the drug had been approved in December 1993 solely for adjunctive anti-seizure use. Steinman et al. analysed the internal industry documents produced in that litigation and traced a strategy in which publication planning, continuing medical education and advisory boards were used as promotional channels. Landefeld and Steinman later described the episode in the New England Journal of Medicine as marketing through misinformation and manipulation. The lesson is not historical: a large share of current gabapentin prescribing is for indications this campaign popularised.
Written into the record, not signed off as a reviewed claim
Combining gabapentin with an opioid was associated with a 60% higher odds of opioid death
In plain words
In a population study of people prescribed opioids, those also taking gabapentin were around 60% more likely to die of an opioid-related cause, and nearly half of gabapentin users were also getting an opioid.
What was measured
Adjusted odds ratio for opioid-related death with concomitant gabapentin
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Gomes et al. ran a nested case-control study in Ontario public drug plan beneficiaries. Moderate-dose and high-dose gabapentin co-prescription with opioids were each associated with roughly a 60% increase in the odds of opioid-related death (adjusted OR 1.56, 95% CI 1.06 to 2.28 and adjusted OR 1.58, 95% CI 1.09 to 2.27). Co-prescription of opioids with NSAIDs showed no such association (adjusted OR 1.14, 0.98 to 1.32), which is the internal control that makes the gabapentin result harder to dismiss as confounding by indication. In 2013, 46.0% of gabapentin users (45,173 of 98,288) received at least one concomitant opioid prescription.
Written into the record, not signed off as a reviewed claim
Documented misuse potential, concentrated in people who also use opioids
In plain words
Gabapentinoids are misused by a small fraction of the general population and by a much larger fraction of people who misuse opioids, and international adverse-event reports of abuse rose sharply after 2012.
What was measured
Prevalence of gabapentinoid abuse by population
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Evoy et al. systematically reviewed 59 studies. Prevalence of gabapentinoid abuse was 1.6% in the general population and ranged from 3% to 68% among people who abuse opioids. An international adverse-event database contained 11,940 reports of gabapentinoid abuse between 2004 and 2015, with more than 75% of them reported since 2012. Risk factors were a history of substance abuse, particularly opioids, and psychiatric comorbidity. The authors noted gabapentinoids are increasingly identified in post-mortem toxicology.
Written into the record, not signed off as a reviewed claim
Perioperative use: 281 trials, 24,682 patients, and no clinically significant analgesia
In plain words
Giving gabapentin or pregabalin around surgery lowered pain scores by less than the amount considered clinically meaningful, and increased dizziness and visual disturbance.
What was measured
Mean difference in postoperative pain intensity on a 100-point scale
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Verret et al. included 281 trials and 24,682 participants. Compared with control, gabapentinoids reduced postoperative pain on a 100-point scale by 10 points at 6 hours (95% CI -12 to -9), 9 at 12 hours, 7 at 24 hours and 3 at 48 hours — all at or below the 10-point minimally important difference. No effect on pain at 72 hours, or on subacute or chronic postoperative pain. Gabapentinoids reduced postoperative nausea and vomiting but increased dizziness and visual disturbance. The authors concluded the results do not support routine perioperative use.
Written into the record, not signed off as a reviewed claim
Prescribing kept rising after the negative evidence arrived
In plain words
The share of American adults taking a gabapentinoid reached 4.0% in 2015 and 4.7% in 2021, after the negative low-back-pain and perioperative evidence had been published.
What was measured
That widespread prescribing of gabapentin for an indication reflects evidence supporting that indication
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Johansen and Maust used the Medical Expenditure Panel Survey through 2021 and reported gabapentinoid users rising from 4.0% of the adult population in 2015 to 4.7% in 2021. Use was much more likely among people also taking other chronic-pain medicines, and new users clearly outnumbered stoppers between 2011-2012 and 2017-2018. The inference this page flags is the common assumption that prescribing volume tracks evidence. Between 2017 and 2021 the evidence for the biggest off-label uses got worse and the prescribing did not fall.
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What is not here
7 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
An alpha-2-delta calcium channel ligand with moderate-quality evidence in two neuropathic pain conditions, essentially no evidence in the back pain it is most often prescribed for, and a $430 million federal settlement over the marketing campaign that created the gap.
Recorded evidence blocks (10)
Q1
On the Gabapentin label: indicated for what?
"Gabapentin is indicated for: Management of postherpetic neuralgia in adults Adjunctive therapy in the treatment of partial onset seizures, with and without secondary generalization, in adults and pediatric patients 3 years and older with epilepsy Gabapentin is indicated for: Postherpetic neuralgia in adults ( 1 )…": indications and usage on Gabapentin's label. DailyMed label · 1af098ad-28b5-463f-8efa-24d70a77d64c · 2026-08-26
Q2
346 registered trials of Gabapentin — at which phases?
Registered studies posting no result
241 of 346
346 registered studies of Gabapentin: 107 phase4, 80 phase3, 67 na, 67 phase2, 23 phase1, 14 na or unstated, 11 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
893 with a PubMed record
Show the evidence
phase4
107
phase3
80
na
67
phase2
67
phase1
23
na or unstated
14
9 more recorded rows
early phase1
11
completed
231
terminated
33
unknown
30
withdrawn
22
recruiting
16
not yet recruiting
7
active not recruiting
5
enrolling by invitation
2
recorded 2026-09-01 · last checked 2026-09-04
Q3
50 of Gabapentin's trials stopped: futility/efficacy, accrual/recruitment, funding/business, other?
futility/efficacy (3), accrual/recruitment (23), funding/business (5) and other (19): Gabapentin's stop wording, clustered. CLINICALTRIALS_SNAPSHOT · 2026-09-01
"poor recruitment"; 50 of 346 registered studies
Show the evidence
Trial
NCT00390013
terminated; "poor recruitment"
NCT00533455
terminated; "Failure to recruit due to polypharmacy"
NCT00573664
terminated; "Interim analysis showed a significant reduction in the pain scores"
NCT00584779
terminated; "See detailed description for termination reason"
NCT00619983
terminated; "Study terminated due to low enrollment"
NCT00735124
terminated; "Changes to surgical practices led to the loss of eligible patients"
14 further recorded trials
NCT00785772
terminated; "See termination reason in detailed description."
NCT00954187
terminated; "PI left institution"
NCT01052896
withdrawn; "Unable to recruit subjects - unworkable"
NCT01067144
terminated; "Trial met futility stopping point"
NCT01112878
withdrawn; "Several studies going on at the same time."
NCT01533753
terminated; "Slow accrual"
NCT01546857
terminated; "No longer able to recruit subjects due to unavailability of orthopedic surgeon."
NCT01588314
withdrawn; "No patients were enrolled. No data \& no study results to report."
NCT01623271
terminated; "Due to limited population of research participants."
NCT01675960
terminated; "unable to enroll"
NCT01678911
terminated; "Study ended due to difficulties in recruitment and low enrollment."
NCT01893632
terminated; "Insufficient recruitment, funding terminated from sponsor"
NCT02076893
terminated; "Interim analysis results indicated need to recruit beyond scope of budget."
NCT02117076
terminated; "Recruitment unsuccessful due to overly restrictive inclusion/exclusion criteria."
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Gabapentin used Gabapentin 900mg — over how long?
Human studies of Gabapentin used "Gabapentin 900mg". ClinicalTrials.gov · 2026-09-01
20 recorded entries; human; tablet; also "gabapentin 1800mg", "Gabapentin - 1800 mg/day", "Gabapentin - 2700 mg/day"
Show the evidence
human
NCT00391716
Gabapentin 900mg
NCT00391716
gabapentin 1800mg
NCT00578552
Gabapentin - 1800 mg/day
NCT00578552
Gabapentin - 2700 mg/day
NCT00755417
Gabapentin Extended-Release (G-ER) 1200 mg
NCT00755417
Gabapentin Extended-Release (G-ER) 1800 mg
14 more recorded rows
humanNCT00778232
Gabapentin tablets 800 mg
humanNCT00778271
Gabapentin 400mg capsules
humanNCT00778765
400 mg Gabapentin Capsules
humanNCT00864058
Gabapentin 400 mg capsules
humanNCT00864058
NEURONTIN® 400 mg capsules
humanNCT00864305
Gabapentin 400 mg capsules, single dose
humanNCT00864760
tablet; Gabapentin 800 mg tablets, single dose (1 tablet)
humanNCT00864760
NEURONTIN® 400 mg capsules, single dose (2 capsules)
humanNCT00865059
Gabapentin 800 mg Tablets, single dose
humanNCT00865059
NEURONTIN® 800 mg Tablets, single dose
humanNCT00974376
gabapentin 1200mg/day
humanNCT01094925
Gabapentin 300mg
humanNCT01094925
Gabapentin 600mg
humanNCT01116583
Gabapentin "Sandoz" 300 mg
recorded 2026-09-01 · last checked 2026-09-04
Q5
Gabapentin's half-life is 5 to 7 hours — which schedules were studied?
5 to 7 hours; Gabapentin elimination half-life is 5 to 7 hours and is unaltered by dose or following multiple dosing.
tmaxpharmacokinetics
2 to 3 hours; Peak plasma concentrations were similar across the entire age group and occurred 2 to 3 hours postdose.
bioavailabilitypharmacokinetics
60 %; Bioavailability of gabapentin is approximately 60%, 47%, 34%, 33%, and 27% following 900 mg/day, 1,200 mg/day, 2,400 mg/day, 3,600 mg/day, and 4,800 mg/day given in 3 divided doses, respectively.
metabolismpharmacokinetics
All pharmacological actions following gabapentin administration are due to the activity of the parent compound; gabapentin is not appreciably metabolized in humans.
recorded 2026-08-26 · last checked 2026-09-04
Q6
Which 128 trials of Gabapentin posted no result?
Posted no result
128 of 128 completed trials
Registrations
NCT00864058, NCT00864305, NCT00864760, NCT00865631, NCT00865059 and NCT00865423, and 122 more
Completion dates
oldest 1998-01; newest 2024-09-01
Show the evidence
Trial
NCT00864058
1998-01
NCT00864305
1998-01
NCT00864760
1999-06
NCT00865631
1999-06
NCT00865059
2001-03
NCT00865423
2001-03
14 further recorded trials
NCT00001482
2001-05
NCT00778232
2002-11
NCT00778271
2002-12
NCT00778401
2002-12
NCT00778765
2002-12
NCT00007670
2003-03
NCT00058890
2004-01
NCT00153283
2004-04
NCT00644748
2004-08
NCT00666770
2004-11
NCT00018291
2005-01
NCT00257270
2005-01
NCT00666939
2005-01
NCT00667108
2005-01
Q7
At the median, Gabapentin's trials enrolled 62 people — anything larger?
Median enrolment
62
Largest enrolment
5000
Registered trials counted
343
Q8
What do 36100 spontaneous reports say about Gabapentin — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Gabapentin appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 36100 reaction mentions were counted: drug hypersensitivity 7198; pain 5639; somnolence 4642; dizziness 4445. FAERS via Open Targets · CHEMBL940 · 2026-06-24
Show the evidence
drug hypersensitivity
7198
pain
5639
somnolence
4642
dizziness
4445
weight increased
2709
confusional state
2685
4 more recorded rows
feeling abnormal
2513
insomnia
2404
drug abuse
2157
withdrawal syndrome
1708
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which 10 reactions does Gabapentin's label not list?
Drug Interactions In Vitro Studies In vitro studies were conducted to investigate the potential of gabapentin to inhibit the major cytochrome P450 enzymes (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) that mediate drug and xenobiotic metabolism using isoform selective marker substrates and human liver microsomal preparations.
pharmacokinetics
1 mM) was a slight degree of inhibition (14% to 30%) of isoform CYP2A6 observed.
clinical_pharmacology
Drug Interactions In Vitro Studies In vitro studies were conducted to investigate the potential of gabapentin to inhibit the major cytochrome P450 enzymes (CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4) that mediate drug and xenobiotic metabolism using isoform selective marker substrates and human liver microsomal preparations.
clinical_pharmacology
1 mM) was a slight degree of inhibition (14% to 30%) of isoform CYP2A6 observed.
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 6 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
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