Gabapentinoid (Alpha-2-Delta Calcium Channel Ligand) Pregnancy: Gabapentin should not be used during pregnancy unless the potential benefit to the mother clearly outweighs the potential risk to the foetus. It crosses the human placenta; data in pregnant women are limited and animal studies have shown reproductive toxicity. Neonatal withdrawal syndrome has been reported in newborns exposed in utero, and co-exposure with opioids may increase this risk. Gabapentin is excreted in human milk — use in breast-feeding mothers only if the benefits clearly outweigh the risks (UK SPC §4.6).

Gabapentin

Brand names: Neurontin

Gabapentin is a gabapentinoid used for neuropathic pain and as an adjunct in focal epilepsy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Initial titration (all indications, adults and adolescents 12 years and above): 300 mg once daily on day 1, 300 mg twice daily on day 2, then 300 mg three times daily on day 3. Epilepsy: effective dosing range 900 to 3600 mg/day. Peripheral neuropathic pain: alternatively start 900 mg/day given as three equally divided doses

Route: Oral — may be given with or without food; swallow whole with sufficient fluid

Frequency: Three times daily (total daily dose divided into three single doses; the maximum interval between doses should not exceed 12 hours)

Max: 3600 mg/day (dosages up to 4800 mg/day have been well tolerated in long-term open-label clinical studies)

After initial titration the dose can be increased in 300 mg/day increments every 2-3 days up to a maximum of 3600 mg/day, based on individual response and tolerability. Minimum time to reach 1800 mg/day is one week, to reach 2400 mg/day a total of 2 weeks, and to reach 3600 mg/day a total of 3 weeks; slower titration may be appropriate for individual patients. Epilepsy typically requires long-term therapy; the three-times-daily interval limit prevents breakthrough convulsions. Peripheral neuropathic pain: efficacy and safety have not been examined in clinical studies for treatment periods longer than 5 months — reassess clinical status if dosing beyond 5 months is required. Patients in poor general health (e.g. low body weight, after organ transplantation) should be titrated more slowly. Elderly (over 65 years): may require dosage adjustment because of declining renal function; somnolence, peripheral oedema and asthenia may be more frequent. Discontinuation: taper gradually over a minimum of 1 week, independent of indication. Paediatric use — see paedDose (children aged 6 years and above, epilepsy); dosing instructions for children under 12 years are given separately in the SPC. Verify all paediatric dosing against a children's formulary before prescribing.

Paediatric dose

Route: Oral

Frequency: Total daily dose divided into three single doses; maximum interval between doses should not exceed 12 hours

Max: Dosages up to 50 mg/kg/day have been well tolerated in a long-term clinical study

Epilepsy, children aged 6 years and above (UK SPC §4.2): starting dose 10 to 15 mg/kg/day, with the effective dose reached by upward titration over a period of approximately three days; effective dose 25 to 35 mg/kg/day. No single per-kg figure is stated — the SPC gives ranges only. US labelling differs (children 3 to 11 years: start 10-15 mg/kg/day; maintenance 40 mg/kg/day at 3-4 years and 25-35 mg/kg/day at 5-11 years). Adolescents aged 12 years and above follow the adult regimen. Verify against a children's formulary before prescribing.

Dose adjustments

Renal

Dosage adjustment is recommended in renal impairment (UK SPC §4.2, Table 2), total daily dose given as three divided doses: creatinine clearance >=80 mL/min, 900-3600 mg/day; 50-79 mL/min, 600-1800 mg/day; 30-49 mL/min, 300-900 mg/day; 15-29 mL/min, 150-600 mg/day; <15 mL/min, 150-300 mg/day. A 150 mg dose is administered as 300 mg every other day. For creatinine clearance <15 mL/min the daily dose should be reduced in proportion to creatinine clearance. Haemodialysis: for anuric patients who have never received gabapentin, a loading dose of 300 to 400 mg then 200 to 300 mg following each 4 hours of haemodialysis, with no treatment on dialysis-free days; for renally impaired patients on haemodialysis, give the Table 2 maintenance dose plus an additional 200 to 300 mg after each 4-hour session.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

2 DOSAGE AND ADMlNlSTRATION Postherpetic Neuralgia (2.1) Dose can be titrated up as needed to a dose of 1800 mg/day Day 1: Single 300 mg dose Day 2: 600 mg/day (i.e., 300 mg two times a day) Day 3: 900 mg/day (i.e., 300 mg three times a day) Epilepsy with Partial Onset Seizures (2.2) Patients 12 years of age and older: starting dose is 300 mg three times daily; may be titrated up to 600 mg three times daily Patients 3 to 11 years of age: starting dose range is 10 to 15 mg/kg/day, given in three divided doses; recommended dose in patients 3 to 4 years of age is 40 mg/kg/day, given in three divided doses; the recommended dose in patients 5 to 11 years of age is 25 to 35 mg/kg/day, given in …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2024-04-02. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

Hypersensitivity to the active substance or to any of the excipients

Side effects

Somnolence, dizziness and ataxia (very common)
Viral infection (very common); pneumonia, respiratory infection, urinary tract infection, otitis media (common)
Headache, tremor, insomnia, paraesthesia, convulsions, dysarthria, amnesia (common)
Nausea, vomiting, diarrhoea, abdominal pain, dyspepsia, constipation, dry mouth (common)
Visual disturbances such as amblyopia and diplopia (common); vertigo (common)
Hostility, confusion, emotional lability, depression, anxiety, nervousness (common)
Not known: anaphylaxis, hypersensitivity syndrome, suicidal ideation, drug dependence, pancreatitis, hepatitis and jaundice, Stevens-Johnson syndrome, toxic epidermal necrolysis and DRESS; rare respiratory depression

Interactions

eMC §4.5 was not captured in this source bundle — the UK interaction list must be verified by the clinician
Opioids and other CNS depressants — respiratory depression and sedation, sometimes resulting in death, have been reported following coadministration of gabapentin with opioids (e.g. morphine, hydrocodone, oxycodone, buprenorphine); observe closely for CNS depression (SPC §4.4 and US FDA label §7.1)
Morphine — gabapentin concentrations increased; may need dose adjustment (US FDA label §7)
Hydrocodone — coadministration with gabapentin decreases hydrocodone exposure (US FDA label §7.1)
Antacids containing aluminium and magnesium hydroxides — mean bioavailability of gabapentin reduced by about 20%; take gabapentin at least 2 hours after the antacid (US FDA label §7.3)
Other antiepileptic medicinal products — gabapentin may be combined without concern for alteration of plasma concentrations of gabapentin or serum concentrations of other antiepileptics (SPC §4.2)

Clinical monograph

How it works

Gabapentin binds the alpha-2-delta subunit of voltage-gated calcium channels, reducing excitatory neurotransmitter release in sensitised neurons.

Prescribing in practice

Titrate up gradually to balance efficacy against sedation and dizziness, and taper when stopping rather than stopping abruptly.
Reduce the dose in renal impairment, as it is cleared renally.
It is a controlled drug in the UK; be alert to misuse and to additive respiratory depression with opioids or other sedatives.

Monitoring

No routine blood monitoring; review pain or seizure response, sedation, mood, and renal function where relevant.

Counselling the patient

Drowsiness and dizziness are common at first and usually settle — take care driving until you know how it affects you.
Do not stop suddenly.
Tell your clinician about low mood or thoughts of self-harm.

Evidence & guidelines

Gabapentin is a first-line option for neuropathic pain (other than trigeminal neuralgia) per NICE CG173.

Reference: MHRA Drug Safety Update 2019 (Gabapentinoids + opioids); NICE NG193 Neuropathic Pain; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Drugs

Pregabalin · Gabapentinoid (Alpha-2-Delta Calcium Channel Ligand)

Pathways