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Anticonvulsant / Neuropathic Analgesic Pregnancy: Avoid in pregnancy — teratogenicity signal; register with UK Epilepsy and Pregnancy Register

Gabapentin

Brand names: Neurontin

Adult dose

Dose: 300-3600 mg/day in divided doses
Route: Oral
Frequency: Three times daily
Max: 3600 mg/day
Start at 300 mg on day 1, 300 mg twice daily day 2, 300 mg three times daily day 3. In elderly: start 100 mg three times daily

Paediatric dose

Dose: Seek specialist opinion N/A/kg
Route: Oral
Frequency: Seek specialist opinion
Max: Seek specialist opinion
Seek specialist opinion

Dose adjustments

Renal

Significant reduction required: eGFR 30-59: max 1400 mg/day; eGFR 15-29: max 700 mg/day; eGFR under 15: max 300 mg/day — renally excreted unchanged

Hepatic

No adjustment required

Paediatric weight-based calculator

Seek specialist opinion

Clinical pearls

  • MHRA 2017 safety alert: Gabapentin and pregabalin associated with fatal respiratory depression, especially with opioids, benzodiazepines, or in patients with respiratory disease — monitor closely in elderly
  • UK Schedule 3 Controlled Drug since April 2019 — prescription and dispensing controls apply
  • Beers Criteria: avoid as first-line in elderly without careful consideration of fall and sedation risk — start low, go slow
  • Renal dosing is critical in elderly — most have impaired renal function; under-dosing reduces efficacy, over-dosing causes toxicity
  • NICE CG173: recommended for neuropathic pain; NICE NG217: adjunct antiepileptic

Contraindications

  • Hypersensitivity to gabapentin

Side effects

  • Dizziness and somnolence (very common — increased in elderly)
  • Ataxia and falls (elderly)
  • Peripheral oedema
  • Weight gain
  • Respiratory depression (especially with opioids)
  • Cognitive impairment

Interactions

  • Opioids (significant — additive CNS/respiratory depression; MHRA 2017 warning)
  • Antacids containing aluminium/magnesium (reduce absorption — separate by 2 hours)
  • Alcohol (additive sedation)

Monitoring

  • Renal function (eGFR — dose adjustment)
  • Sedation and falls risk
  • Respiratory rate (if on concurrent opioids)
  • Oedema

Reference: BNFc; BNF 90; NICE CG173 (Neuropathic Pain); MHRA Drug Safety Update 2017; AGS Beers Criteria 2023. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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