What is the recommended dose of gabapentin (Neurontin) or pregabalin (Lyrica) for low back pain (LBP) with radiculopathy?

Recommended Dosing of Gabapentin and Pregabalin for Low Back Pain with Radiculopathy

For low back pain with radiculopathy, start gabapentin at 300 mg three times daily and titrate up to 1800-3600 mg/day in divided doses, or start pregabalin at 75 mg twice daily and titrate to 150-300 mg twice daily (300-600 mg/day). 1, 2

Gabapentin Dosing Protocol

Initial Dosing:

• Start with 300 mg once daily on Day 1, increase to 300 mg twice daily on Day 2, then 300 mg three times daily (900 mg/day) on Day 3 1
• This gradual titration minimizes adverse effects while establishing therapeutic levels 1

Maintenance Dosing:

• Target dose: 300-600 mg three times daily (900-1800 mg/day) 1
• Maximum studied dose: 3600 mg/day, though additional benefit above 1800 mg/day has not been clearly demonstrated 1
• Doses should be divided three times daily with maximum 12-hour intervals between doses 1

Evidence for Radiculopathy:

• Gabapentin shows small to moderate short-term benefits specifically for radicular pain 3, 4
• Studies used doses titrated up to 1200-3600 mg/day, though results were inconsistent across trials 3
• One open-label study demonstrated efficacy at up to 1800 mg/day divided in 3 doses for chronic radiculopathy 5

Pregabalin Dosing Protocol

Initial Dosing:

• Start with 75 mg twice daily or 50 mg three times daily (150 mg/day total) 2
• Increase to 150 mg twice daily (300 mg/day) within 1 week based on efficacy and tolerability 2

Maintenance Dosing:

• Recommended range: 150-300 mg twice daily (300-600 mg/day) 2
• For patients not achieving adequate pain relief after 2-4 weeks on 300 mg/day who tolerate the medication well, may increase to 300 mg twice daily (600 mg/day maximum) 2
• Doses above 300 mg/day should be reserved only for patients with ongoing pain who tolerate lower doses, due to dose-dependent adverse effects 2

Evidence for Radiculopathy:

• Recent meta-analysis shows pregabalin more effective than gabapentin for pain reduction in short-term follow-up (≤6 weeks), but no difference in long-term follow-up (6-12 weeks) 6
• For chronic radicular back pain, evidence is limited with inconsistent findings across trials 3

Comparative Considerations

Choosing Between Gabapentin and Pregabalin:

• Pregabalin demonstrates faster onset of pain relief in the first 6 weeks compared to gabapentin 6
• Both medications show similar adverse event profiles (dizziness and sedation) with no significant difference in incidence 6
• Pregabalin requires only twice-daily dosing versus three times daily for gabapentin, potentially improving adherence 2
• Cost considerations may favor gabapentin as it is available generically 1

Renal Dose Adjustments

Gabapentin:

• CrCl ≥60 mL/min: 300-1200 mg three times daily 1
• CrCl 30-59 mL/min: 200-700 mg twice daily 1
• CrCl 15-29 mL/min: 200-700 mg once daily 1
• CrCl <15 mL/min: 100-300 mg once daily 1
• Hemodialysis: Maintenance dose based on CrCl plus supplemental dose after each 4-hour dialysis session 1

Pregabalin:

• Requires dose adjustment in adult patients with reduced renal function based on creatinine clearance 2
• Supplemental doses needed after hemodialysis 2
• Pediatric renal dosing has not been established 2

Critical Limitations and Pitfalls

Evidence Quality Issues:

• Most gabapentin trials for radiculopathy were poor-quality with inconsistent findings 3
• Pregabalin shows no benefit for chronic nonradicular back pain and may actually worsen function 3
• Neither medication is FDA-approved specifically for low back pain with or without radiculopathy 3

Common Pitfalls to Avoid:

• Do not use these medications for nonradicular low back pain—evidence shows no benefit and potential harm 3, 7
• Do not exceed maximum doses (3600 mg/day gabapentin, 600 mg/day pregabalin) as higher doses increase adverse effects without additional benefit 1, 2
• Monitor for sedation, dizziness, and peripheral edema, particularly during dose titration 4
• Pregabalin may adversely affect balance and gait at initial doses and during dose increases, though tolerance typically develops at maintenance doses 8
• Always taper gradually over minimum 1 week when discontinuing to avoid withdrawal symptoms 1, 2

Elderly Patients:

• Use caution with dose selection due to age-related decline in renal function 1
• Adjust doses based on creatinine clearance values 1

Integration with Other Therapies

Combination Approach:

• The American College of Physicians recommends adding gabapentin to NSAIDs for the neuropathic component of radiculopathy 4
• If insufficient response, consider adding tricyclic antidepressants or duloxetine 4
• Time-limited courses are recommended; reassess if no response occurs 3