Maximum Recommended Dose of Gabapentin
The maximum recommended dose of gabapentin is 3600 mg/day in 3 divided doses, though effective doses can range from 1800-3600 mg/day depending on the indication and patient factors. 1, 2
Dosing Guidelines by Indication
Neuropathic Pain
- Starting dose: 100-300 mg at bedtime or 100-300 mg three times daily
- Titration: Increase by 100-300 mg every 1-7 days as tolerated
- Effective dose range: 1800-3600 mg/day in 3 divided doses
- Duration of adequate trial: 3-8 weeks for titration plus 2 weeks at maximum dose 1
Postherpetic Neuralgia
- Day 1: 300 mg once daily
- Day 2: 600 mg/day (300 mg twice daily)
- Day 3: 900 mg/day (300 mg three times daily)
- Target dose: 1800 mg/day (600 mg three times daily)
- Maximum dose: 3600 mg/day, though additional benefit beyond 1800 mg/day has not been consistently demonstrated 2
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
- Maximum time between doses: Should not exceed 12 hours 2
Dosage Adjustments for Special Populations
Renal Impairment
Dosage must be reduced based on creatinine clearance:
| Creatinine Clearance (mL/min) | Total Daily Dose Range (mg/day) |
|---|---|
| ≥60 | 900-3600 |
| >30-59 | 400-1400 |
| >15-29 | 200-700 |
| ≤15 | 100-300 |
Patients on hemodialysis require supplemental post-dialysis doses 2
Elderly Patients
Lower starting doses and slower titration are recommended due to potentially decreased renal function 1, 2
Clinical Considerations
Efficacy Evidence
- Moderate-quality evidence shows that gabapentin at doses of 1800-3600 mg/day provides good pain relief in postherpetic neuralgia and diabetic neuropathy, with 30-40% of patients achieving at least 50% pain reduction 3, 4
- An adequate trial may require 2 months or more to determine effectiveness 1
Adverse Effects
- Most common side effects include dizziness (19%), somnolence (14%), peripheral edema (7%), and gait disturbance (9%) 3
- Adverse effects are typically mild to moderate and often subside within approximately 10 days from treatment initiation 5
- Adverse events occur more frequently with gabapentin (63%) compared to placebo (49%) 3
Important Precautions
- Monitor for worsening mental status/sedation, especially during titration
- Maximum time between doses should not exceed 12 hours
- If discontinuing gabapentin, taper gradually over a minimum of 1 week to avoid withdrawal symptoms
- Half-tablets not used within 28 days of dividing should be discarded 2
Gabapentin can be administered with or without food, which provides flexibility in dosing schedules and may improve tolerability for some patients 2.