Gabapentin Dosing and Frequency for Adults
The typical starting dose of gabapentin for adults is 100-300 mg once daily at bedtime, gradually increasing to 900-3600 mg daily in divided doses (2-3 times per day) based on response and tolerability. 1, 2
Initial Dosing Strategy
- Starting dose: 100-300 mg at bedtime on day 1
- Titration schedule:
- Day 1: 300 mg once daily (at bedtime)
- Day 2: 300 mg twice daily (600 mg/day)
- Day 3: 300 mg three times daily (900 mg/day)
- Then increase by 300 mg/day every 3-5 days as needed and tolerated
Dosing by Indication
Neuropathic Pain
- FDA-approved starting dose for postherpetic neuralgia 2:
- Day 1: 300 mg once
- Day 2: 300 mg twice daily (600 mg/day)
- Day 3: 300 mg three times daily (900 mg/day)
- Target dose: 1800 mg/day (600 mg three times daily)
Epilepsy (Adults and Children ≥12 years)
- Starting dose: 300 mg three times daily
- Maintenance dose: 300-600 mg three times daily
- Maximum dose: 2400-3600 mg/day 2
Dosing Considerations
Dose Adjustments
Renal impairment: Dose reduction required based on creatinine clearance 2
- CrCl ≥60 mL/min: 900-3600 mg/day in three divided doses
- CrCl 30-59 mL/min: 400-1400 mg/day in two divided doses
- CrCl 15-29 mL/min: 200-700 mg/day as a single daily dose
- CrCl <15 mL/min: 100-300 mg/day as a single daily dose
Elderly patients: Start at lower doses and titrate more slowly due to decreased renal function 2
Administration Guidelines
- Can be taken with or without food
- Divided doses should be spaced evenly throughout the day
- Maximum time between doses should not exceed 12 hours 2
Efficacy and Tolerability
- Effective dose range: 1800-3600 mg/day for most neuropathic pain conditions 1, 3
- Response rate: Approximately 30-40% of patients achieve at least 50% pain relief at doses of 1200 mg/day or greater 3
Common Side Effects
- Dizziness (19%)
- Somnolence (14%)
- Peripheral edema (7%)
- Gait disturbance (14%) 3
Important Clinical Pearls
- Titration speed: Dose increments of 50-100% every few days are generally well tolerated, but slower titration is recommended for elderly or medically frail patients 1
- Therapeutic assessment: Optimal pain control may take several weeks to achieve
- Discontinuation: Should be done gradually over at least 1 week to avoid withdrawal symptoms 2
- Monitoring: Regular assessment of pain relief and side effects is essential to determine optimal dosing
The evidence consistently shows that higher maintenance doses (1800-3600 mg/day) provide better efficacy for neuropathic pain without significantly increasing adverse effects, though individual dose requirements vary based on patient factors and response 3, 4.