What is the maximum recommended dose of gabapentin (Neurontin) for neuropathic pain and epilepsy?

Maximum Dosing of Gabapentin

The maximum recommended dose of gabapentin is 3600 mg per day for both neuropathic pain and epilepsy, with dosing typically divided into three times daily administration. 1

Dosing Guidelines by Indication

For Neuropathic Pain:

• Starting dose: 300 mg on day 1,600 mg on day 2 (300 mg twice daily), 900 mg on day 3 (300 mg three times daily)
• Titration: Increase gradually based on response and tolerability
• Effective dose range: 1800-3600 mg/day
• Maximum dose: 3600 mg/day 2, 1

For Epilepsy:

• Adults and children ≥12 years:
  • Starting dose: 300 mg three times daily
  • Maintenance dose: 300-600 mg three times daily
  • Maximum dose: 3600 mg/day 1
• Children 3-11 years:
  • Starting dose: 10-15 mg/kg/day in three divided doses
  • Maintenance dose:
    • Ages 3-4 years: 40 mg/kg/day in three divided doses
    • Ages 5-11 years: 25-35 mg/kg/day in three divided doses
  • Maximum dose: Up to 50 mg/kg/day has been well tolerated 1

Dosage Adjustment for Special Populations

Renal Impairment

Dosage reduction is required based on creatinine clearance:

• CrCl ≥60 mL/min: 900-3600 mg/day (300-1200 mg TID)
• CrCl 30-59 mL/min: 400-1400 mg/day (200-700 mg BID)
• CrCl 15-29 mL/min: 200-700 mg/day (100-300 mg QD)
• CrCl <15 mL/min: 100-300 mg/day (100-300 mg QD) 1

Elderly Patients

• Lower starting doses and slower titration are recommended
• Dose should be adjusted based on renal function, which commonly declines with age 1

Administration Guidelines

• Gabapentin can be taken with or without food
• The maximum time between doses should not exceed 12 hours
• If using scored tablets (600 mg or 800 mg), unused half-tablets should be used for the next dose or discarded after 28 days 1

Efficacy Considerations

• For neuropathic pain, clinical trials have demonstrated efficacy across doses from 1800-3600 mg/day
• No additional benefit was consistently demonstrated for doses above 1800 mg/day in postherpetic neuralgia, though some patients may require higher doses 1, 3
• For epilepsy, doses up to 2400 mg/day have been well-tolerated in long-term studies, with doses up to 3600 mg/day administered for shorter durations 1

Common Side Effects

• Dizziness (19%)
• Somnolence (14%)
• Peripheral edema (7%)
• Gait disturbance (9%)
• Dry mouth
• Constipation 2, 3

Important Clinical Considerations

• When discontinuing gabapentin, taper gradually over at least 1 week to minimize withdrawal symptoms 1
• Response rates vary by condition: approximately 38% of patients with diabetic neuropathy and 32% with postherpetic neuralgia achieve at least 50% pain reduction 3
• Adverse events are dose-dependent but not necessarily more frequent at higher maintenance doses when appropriate titration is used 4

Gabapentin's unique pharmacokinetics (non-linear absorption due to saturable transport) make careful titration particularly important for optimizing efficacy while minimizing side effects.