Maximum Daily Dose of Gabapentin
The maximum daily dose of gabapentin is 3600 mg/day for adults with normal renal function, as established by the FDA label and clinical guidelines. 1, 2
Dosing Guidelines by Indication
Postherpetic Neuralgia
- Starting dose: 300 mg on Day 1,600 mg/day on Day 2,900 mg/day on Day 3
- Effective dose range: 1800-3600 mg/day
- Note: While efficacy has been demonstrated across this range, additional benefit beyond 1800 mg/day has not been clearly established 1
Epilepsy with Partial Onset Seizures
- Adults and patients ≥12 years:
- Starting dose: 300 mg three times daily
- Maintenance dose: 300-600 mg three times daily (900-1800 mg/day)
- Maximum dose: 3600 mg/day 1
- Pediatric patients (3-11 years):
- Starting dose: 10-15 mg/kg/day in three divided doses
- Maintenance dose:
- Ages 3-4: 40 mg/kg/day in three divided doses
- Ages 5-11: 25-35 mg/kg/day in three divided doses
- Maximum studied dose: 50 mg/kg/day 1
Neuropathic Pain
- Recommended dose range: 900-1800 mg/day for most patients
- Maximum dose: 3600 mg/day 2
Dosage Adjustment in Renal Impairment
Renal function significantly impacts gabapentin dosing requirements:
| Creatinine Clearance (mL/min) | Total Daily Dose Range (mg/day) | Dose Regimen |
|---|---|---|
| ≥60 | 900-3600 | 300-1200 mg TID |
| >30-59 | 400-1400 | 200-700 mg BID |
| >15-29 | 200-700 | 200-700 mg QD |
| ≤15 | 100-300 | 100-300 mg QD |
Patients on hemodialysis require supplemental post-hemodialysis doses 1, 2
Administration Considerations
- Administer gabapentin orally with or without food
- Maximum time between doses should not exceed 12 hours
- Dose titration is recommended to minimize adverse effects
- When discontinuing, taper gradually over at least 1 week to avoid withdrawal symptoms 1
Common Adverse Effects
At higher doses, gabapentin can produce dose-dependent adverse effects:
Special Populations
Elderly Patients
- More likely to have decreased renal function
- Dose should be adjusted based on creatinine clearance values 1
Clinical Efficacy Considerations
- For neuropathic pain, approximately 38% of patients achieve substantial pain relief (≥50% reduction) with gabapentin at doses ≥1200 mg/day compared to 21% with placebo 3
- While the maximum approved dose is 3600 mg/day, clinical studies show that many patients achieve adequate pain control at 1800 mg/day 3, 4
Important Caveats
- Adverse events increase with higher doses, so the optimal dose should balance efficacy with tolerability
- Titration should be slower in elderly patients or those with comorbidities
- The risk of adverse effects increases significantly at doses approaching the maximum of 3600 mg/day
- Withdrawal should always be gradual to prevent discontinuation symptoms