Gabapentin Dosing for Radiculopathy
For radiculopathy, gabapentin should be initiated at 100-300 mg at bedtime or 100-300 mg three times daily, with gradual titration up to 1800-3600 mg/day in divided doses over several weeks. 1, 2
Initial Dosing and Titration
- Start with 100-300 mg at bedtime or 100-300 mg three times daily 3, 1
- Increase by 100-300 mg every 1-7 days as tolerated 3, 1
- Titrate until adequate pain relief is achieved or dose-limiting side effects occur 1
- Maximum daily dose is 3600 mg/day in three divided doses 3, 2
Evidence for Radiculopathy
- Studies suggest that lumbosacral radiculopathy may be relatively refractory to first-line medications compared to other neuropathic pain conditions 3
- An open pilot study showed significant reduction in pain when gabapentin was used up to 3600 mg/day for discogenic lumbosacral radiculopathy, with better results when treatment was initiated early 4
- In a study of 35 patients with chronic radiculopathy, gabapentin at doses up to 1800 mg/day (divided in 3 doses) significantly improved pain intensity, quality of life, and functional disability 5
Dosing Schedule
- Day 1: 300 mg once daily
- Day 2: 300 mg twice daily (600 mg/day)
- Day 3: 300 mg three times daily (900 mg/day)
- Continue titration as needed for pain relief 2
- An adequate trial requires 3-8 weeks for titration plus 2 weeks at maximum dose 3
Efficacy Considerations
- Clinical studies have demonstrated efficacy across a dose range of 1800-3600 mg/day 2
- Additional benefit of using doses greater than 1800 mg/day was not consistently demonstrated in clinical studies 2
- A recent meta-analysis found that pregabalin may be more effective than gabapentin for lumbar radiculopathy in short-term follow-up (≤6 weeks), but there was no difference in long-term follow-up (6-12 weeks) 6
Special Populations
- For elderly patients, consider lower starting doses and slower titration due to potential decreased renal function 1, 2
- In patients with renal impairment, dosage adjustment is necessary 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 once daily
- CrCl <15 mL/min: 100-300 mg/day once daily
Side Effects and Management
- Common side effects include dizziness, somnolence, dry mouth, and constipation 3
- Side effects can be minimized by starting with lower dosages and titrating cautiously 1
- Maximum time between doses should not exceed 12 hours 2
- If discontinuing gabapentin, taper gradually over a minimum of 1 week to avoid withdrawal symptoms 2