Gabapentin Dosing and Frequency
For neuropathic pain, start gabapentin at 300 mg once daily (or 100-300 mg at bedtime), then titrate to 300 mg three times daily by day 3, with a target maintenance dose of 1800-3600 mg/day divided into three doses. 1
Starting Dose and Initial Titration
For Postherpetic Neuralgia (FDA-approved indication):
- Day 1: 300 mg once daily 1
- Day 2: 600 mg/day (300 mg twice daily) 1
- Day 3: 900 mg/day (300 mg three times daily) 1
- Continue titrating upward as needed for pain relief 1
For General Neuropathic Pain:
- Start at 100-300 mg at bedtime OR 100-300 mg three times daily 2
- Increase by 100-300 mg every 1-7 days as tolerated 2
- For elderly or medically frail patients, use slower titration with increases every 3-7 days 3
Maintenance Dosing
Target Therapeutic Dose:
- Recommended effective range: 1800-3600 mg/day in three divided doses 1, 2
- The 1800 mg/day dose (600 mg three times daily) is the minimum effective dose for most patients 1, 4
- Doses up to 3600 mg/day may be needed in some patients and have been well tolerated 1, 4
- Maximum time between doses should not exceed 12 hours 1
Clinical efficacy data:
- In postherpetic neuralgia, 32% of patients achieve at least 50% pain relief with gabapentin ≥1200 mg/day versus 17% with placebo (NNT 6.7) 5
- In diabetic neuropathy, 38% achieve at least 50% pain relief with gabapentin ≥1200 mg/day versus 21% with placebo (NNT 5.9) 5
- Higher doses (>1800 mg/day) were not consistently more effective than 1800 mg/day in clinical trials, though individual patients may benefit 1
Condition-Specific Dosing
Epilepsy (Partial Onset Seizures):
- Adults and children ≥12 years: Start 300 mg three times daily, maintain at 300-600 mg three times daily 1
- Doses up to 2400 mg/day well tolerated; 3600 mg/day used in some patients 1
Pediatric Epilepsy (Ages 3-11):
- Starting dose: 10-15 mg/kg/day in three divided doses 1
- Ages 3-4: Maintenance 40 mg/kg/day in three divided doses 1
- Ages 5-11: Maintenance 25-35 mg/kg/day in three divided doses 1
Renal Dose Adjustments
Mandatory dose reductions based on creatinine clearance (CrCl): 1
- CrCl ≥60 mL/min: 900-3600 mg/day (300-1200 mg three times daily) 1
- CrCl 30-59 mL/min: 400-1400 mg/day (200-700 mg twice daily) 1
- CrCl 15-29 mL/min: 200-700 mg/day (200-700 mg once daily) 1
- CrCl <15 mL/min: 100-300 mg/day (100-300 mg once daily) 1
- Hemodialysis patients: Maintenance dose based on CrCl plus supplemental post-dialysis dose of 125-350 mg after each 4-hour dialysis session 1
Duration of Therapeutic Trial
Allow adequate time to assess efficacy:
- Minimum trial duration: 3-8 weeks for titration plus 2 weeks at maximum tolerated dose 2
- An adequate therapeutic trial may require 2 months or more 2
- Effects may be noticeable within the first week at therapeutic doses 4
Discontinuation
Taper gradually when stopping gabapentin:
- Discontinue over a minimum of 1 week to avoid withdrawal symptoms 1
- A longer taper period may be needed at prescriber's discretion 1
Common Adverse Effects
Expect dose-dependent side effects: 5
- Dizziness (19% of patients) 5
- Somnolence (14%) 5
- Peripheral edema (7%) 5
- Gait disturbance (14%) 5
- These effects are typically mild to moderate and often transient, usually subsiding within approximately 10 days 4
Adverse event withdrawals occur in 11% of patients versus 8.2% with placebo (NNH 30) 5
Clinical Pearls
- Gabapentin has nonlinear pharmacokinetics, making dose titration less predictable than pregabalin 2, 6
- The drug has a favorable safety profile with minimal drug interactions 3
- About 3-4 out of 10 patients achieve meaningful pain relief (≥50% reduction), while over half will not have worthwhile benefit 5
- Elderly patients require lower starting doses and slower titration due to age-related decline in renal function 1
- Gabapentin 250 mg as a single dose for acute postoperative pain has limited clinical utility (NNT 11) and is inferior to standard analgesics 7