(gabapentin · DailyMed)
GABIX 100 MG CAPSULES
GABAPENTIN
What it does
Gabapentin is a medication mainly used to treat seizures and nerve pain. It belongs to a group of drugs called antiepileptics.
Commonly used for: seizures (epilepsy), nerve pain (neuropathic pain)
Read more in plain English ↓Plain-language summary for general understanding - not medical advice. Always follow your pharmacist/doctor.
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Source: Pharmacy and Poisons Board · fetched 2026-01-28 21:45:05 · updated 2026-07-20 11:19:30
Drug Interactions
65Pharmacodynamic Warnings
Gabapentin appears in TABLE 11: Drugs with CNS depressant effects
Gabapentin appears in TABLE 18: Drugs that cause hyponatraemia
Severe (7)
Antiepileptics - decreases absorption
Iron chelators (dexrazoxane) might decrease the absorption of antiepileptics (fosphenytoin, phenytoin). Avoid.
Antiepileptics - decreases exposure
Lumacaftor is predicted to decrease the exposure to antiepileptics (carbamazepine, fosphenytoin, phenobarbital, phenytoin, primidone). Avoid.
Antiepileptics - decreases concentration
St John’s wort is predicted to decrease the concentration of antiepileptics (fosphenytoin, phenobarbital, phenytoin, primidone). Avoid.
Antiepileptics - increases risk of overheating and dehydration
Hydroxyzine potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - increases risk of overheating and dehydration
Haloperidol potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - decreases absorption
Dexrazoxane might decrease the absorption of antiepileptics (fosphenytoin, phenytoin). Avoid.
Antiepileptics - increases risk of overheating and dehydration
Oxybutynin potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Moderate (25)
Antiepileptics - increases concentration
Intravenous chloramphenicol increases the concentration of antiepileptics (fosphenytoin, phenytoin) and antiepileptics (fosphenytoin, phenytoin) affect the concentration of intravenous chloramphenicol
Antiepileptics - decreases concentration
Diazoxide decreases the concentration of antiepileptics (fosphenytoin, phenytoin) and antiepileptics (fosphenytoin, phenytoin) are predicted to decrease the effects of diazoxide. Monitor concentration
Antiepileptics - increases concentration
Disulfiramincreasestheconcentrationofantiepileptics (fosphenytoin,phenytoin).Monitorconcentrationandadjust dose.rStudy →AlsoseeTABLE12p.1520
Antiepileptics - increases concentration
Fluorouracilincreasestheconcentrationofantiepileptics (fosphenytoin,phenytoin).Monitorconcentrationandadjust dose.rAnecdotal 1xidneppA|snoitcaretnI A1 https://www.facebook.c (Books-Courses-Medic
Antiepileptics - decreases concentration
Folates are predicted to decrease the concentration of antiepileptics (fosphenytoin, phenobarbital, phenytoin, primidone). Monitor concentration and adjust dose.
Unknown (33)
Antiepileptics - increases risk of overheating and dehydration
Acetazolamide potentially increases the risk of overheating and dehydration when given with antiepileptics (zonisamide). Avoid in children.
Antiepileptics - increases risk of visual disturbances
Alcohol potentially increases the risk of visual disturbances when given with antiepileptics (retigabine).
Antiepileptics - decreases exposure
Enzalutamide is predicted to slightly decrease the exposure to antiepileptics (brivaracetam).
Antiepileptics - decreases exposure
Apalutamidepotentiallydecreasestheexposureto antiepileptics(valproate).nTheoretical
Antiepileptics - increases concentration
Capecitabine increases the concentration of antiepileptics (fosphenytoin, phenytoin).
Data from BNF 85 (British National Formulary). This is not a substitute for professional medical advice. Matched via: class
About this medicine
Gabapentin is a medication mainly used to treat seizures and nerve pain. It belongs to a group of drugs called antiepileptics.
What it treats
- seizures (epilepsy)
- nerve pain (neuropathic pain)
How it works
Gabapentin works by affecting the way nerves send messages to your brain, helping to reduce seizures and relieve pain.
Who it's for
Gabapentin is prescribed for individuals with epilepsy and those suffering from nerve pain.
Drug class
Antiepileptics
Cautions
- • Be careful if you are taking other medications that can make you drowsy or dizzy.
- • Use caution if you are taking drugs that can lower sodium levels in the blood.
AI-assisted summary grounded in BNF data - general information only, not medical advice. Always confirm with your pharmacist or doctor.
Clinical monograph: Gabapentin
BNF-referencedGabapentin is an anticonvulsant medication primarily used to treat epilepsy and neuropathic pain. It is particularly effective as an adjunctive therapy for focal seizures with or without secondary generalization. Gabapentin is also utilized off-label for conditions such as neuropathic pain and spasticity associated with multiple sclerosis. It is administrated orally and is known for its relatively low toxicity, providing a wide therapeutic index.
Indications
- Epilepsy
- Focal seizures with or without secondary generalization
- Neuropathic pain
- Spasticity in multiple sclerosis
- Muscle symptoms in motor neurone disease
Dosage
Adults: Initially 300 mg once daily for 1–2 weeks, then 300 mg twice daily for 1–2 weeks, followed by 300 mg 3 times a day for 1–2 weeks. Adjustments should be made according to response; maximum usual dose is 0.9–3.6 g daily in 3 divided doses (
Mechanism of action
Gabapentin primarily acts on the auxiliary α2δ-1 subunit of voltage-gated calcium channels, inhibiting their action and subsequently reducing the release of excitatory neurotransmitters. This mechanism is thought to contribute to its efficacy in treating neuropathic pain and seizures. Gabapentin may also influence adenosine receptors and voltage-gated potassium channels, although the clinical significance of these effects remains unclear.
Pharmacodynamics
Gabapentin is classified as an anticonvulsant that inhibits the release of excitatory neurotransmitters. Its wide therapeutic index makes it safer in overdoses, with high doses not leading to fatal outcomes in animal studies. While effective in treating neuropathic pain and seizure disorders, it is not effective for absence seizures and should be used cautiously in patients with mixed seizure disorders. Gabapentin has been associated with serious hypersensitivity reactions, including DRESS syndrome.
Pharmacokinetics
Gabapentin is absorbed from the gastrointestinal tract with peak plasma concentrations occurring about 2 to 3 hours post-administration. It does not bind significantly to plasma proteins and is eliminated primarily through renal excretion. The drug's half-life is approximately 5 to 7 hours, necessitating multiple daily doses for therapeutic effect. Dose adjustments may be required in patients with renal impairment.
Adverse effects
- Dizziness
- Somnolence
- Fatigue
- Ataxia
- Nausea
- Vomiting
- Peripheral edema
- Visual disturbances
- Mood changes
- Respiratory depression
Interactions
- Opioids (increased risk of respiratory depression)
- CNS depressants (increased sedation)
- Antacids (may decrease gabapentin absorption if taken concurrently)
Precautions
- Use with caution in patients with compromised respiratory function
- Use with caution in patients with renal impairment
- Monitor for signs of suicidal thoughts or behavior
- Monitor for signs of hypersensitivity reactions (DRESS)
Pregnancy
Gabapentin should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Consult a healthcare professional for individual assessment.
Breast-feeding
Gabapentin is excreted in breast milk; caution is advised when administering to breastfeeding mothers.
Storage
Store in a cool, dry place, away from direct sunlight. Keep out of reach of children.
Formulations
- Capsules
- Tablets
- Oral solution
AI-synthesized from BNF references - general information only, not a substitute for professional medical advice or the current BNF. Verify doses with a pharmacist.
Molecular reference: Gabapentin
PubChem CID 3446Molecular formula: C9H17NO2
Mechanism of action
The precise mechanism through which gabapentin exerts its therapeutic effects is unclear. The primary mode of action appears to be at the auxillary α2δ-1 subunit of voltage-gated calcium channels (though a low affinity for the α2δ-2 subunit has also been reported). The major function of these subunits is to facilitate the movement of pore-forming α1 subunits of calcium channels from the endoplasmic reticulum to the cell membrane of pre-synaptic neurons. There is evidence that chronic pain states can cause an increase in the expression of α2δ subunits and that these changes correlate with hyperalgesia. Gabapentin appears to inhibit the action of α2δ-1 subunits, thus decreasing the density of pre-synaptic voltage-gated calcium channels and subsequent release of excitatory neurotransmitters. It is likely that this inhibition is also responsible for the anti-epileptic action of gabapentin. There is some evidence that gabapentin also acts on adenosine receptors and voltage-gated potassium channels, though the clinical relevance of its action at these sites is unclear. Although the exact mechanism by which gabapentin exerts its analgesic effects is not known, the drug has been shown to prevent allodynia (pain-related behavior in response to normally innocuous stimuli) and hyperalgesia (exaggerated response to painful stimuli) in several models of neuropathic pain. Gabapentin also has been shown to decrease pain-related responses after peripheral inflammation in animals; however, the drug has not altered immediate pain-related behaviors. The clinical relevance of these findings is not known. In vitro studies demonstrate that gabapentin binds to the alpha2delta subunit of voltage-activated calcium channels; however, the clinical importance of this effect is not known. Gabapentin is an anticonvulsant agent structurally related to the inhibitory CNS neurotransmitter gamma-aminobutyric acid (GABA). Gabapentin enacarbil is a prodrug of gabapentin that is rapidly converted to gabapentin following oral administration; the therapeutic effects of gabapentin enacarbil are attributed to gabapentin. Although gabapentin was developed as a structural analog of GABA that would penetrate the blood-brain barrier (unlike GABA) and mimic the action of GABA at inhibitory neuronal synapses, the drug has no direct GABA-mimetic action and its precise mechanism of action has not been elucidated. Results of some studies in animals indicate that gabapentin protects against seizure and/or tonic extensions induced by the GABA antagonists picrotoxin and bicuculline or by GABA synthesis inhibitors (e.g., 3-mercaptopropionic acid, isonicotinic acid, semicarbazide). However, gabapentin does not appear to bind to GABA receptors nor affect GABA reuptake or metabolism and does not act as a precursor of GABA or of other substances active at GABA receptors. Gabapentin also has no affinity for binding sites on common neuroreceptors (e.g., benzodiazepine; glutamate; quisqualate; kainate; strychnine-insensitive or -sensitive glycine; alpha1-, alpha2-, or beta-adrenergic; adenosine A1 or A2; cholinergic [muscarinic or nicotinic]; dopamine D1 or D2; histamine H1; type 1 or 2 serotonergic [5-HT1 or 5-HT2]; opiate mc, delta, or k) or ion channels (e.g., voltage-sensitive calcium channel sites labeled with nitrendipine or diltiazem, voltage-sensitive sodium channel sites labeled with batrachotoxinin A 20alpha-benzoate). Conflicting results have been reported in studies of gabapentin affinity for and activity at N-methyl-d-aspartic acid (NMDA) receptors. Currently, the clinical management of visceral pain remains unsatisfactory for many patients suffering from this disease. While preliminary animal studies have suggested the effectiveness of gabapentin in successfully treating visceral pain, the mechanism underlying its analgesic effect remains unclear. Evidence from other studies has demonstrated the involvement of protein kinase C (PKC) and extracellular signal-regulated kina
Pharmacodynamics
Gabapentin is an anti-convulsant medication that inhibits the release of excitatory neurotransmitters, allowing for its use against pathologic neurotransmission such as that seen in neuropathic pain and seizure disorders. It has a wide therapeutic index, with doses in excess of 8000 mg/kg failing to cause a fatal reaction in rats. Gabapentin is ineffective in absence seizures and should be used in caution in patients with mixed seizure disorders involving absence seizures. Gabapentin has been associated with drug reaction with eosinophilia and systemic symptoms (DRESS), otherwise known as multi-organ hypersensitivity. This reaction can prove fatal and early symptoms such as fever, lymphadenopathy, and rash should be promptly investigated.
Source: PubChem (NCBI) · pathways from PathBank, Reactome, WikiPathways & PharmGKB.
This drug in other countries
The same active ingredient registered across other registries we cover - including different brands.
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