Gabapentin vs. Gabapentin Enacarbil for Neuropathic Pain
Gabapentin is recommended as the first-line treatment for neuropathic pain, with standard gabapentin being preferred over gabapentin enacarbil (Gabapin NT) due to its established efficacy, lower cost, and extensive clinical evidence. 1, 2
Medication Comparison
Standard Gabapentin (Gabapin)
- Recommended as first-line oral pharmacological treatment for neuropathic pain by clinical guidelines 1
- Dosing: 900-3600 mg/day in divided doses 2
- Provides good levels of pain relief in postherpetic neuralgia and diabetic neuropathy 3
- About 3-4 out of 10 patients achieve at least 50% pain reduction 3
- NNT (Number Needed to Treat) for diabetic neuropathy: 5.9 3
Gabapentin Enacarbil (Gabapin NT)
- Prodrug of gabapentin with improved bioavailability
- Less evidence specifically supporting its use in neuropathic pain
- More expensive than standard gabapentin
- Similar efficacy profile but no demonstrated superiority over standard gabapentin for neuropathic pain
Dosing and Titration
For optimal results with standard gabapentin:
- Start at 300 mg on day 1
- Increase to 600 mg on day 2
- Reach 900 mg by day 3 4
- Gradually titrate to 1800-3600 mg/day based on response and tolerability 2, 4
- Dose adjustments needed for renal impairment 2:
- CrCl ≥60 mL/min: 900-3600 mg/day (300-1200 mg TID)
- CrCl 30-59 mL/min: 400-1400 mg/day (200-700 mg BID)
- CrCl 15-29 mL/min: 200-700 mg/day (QD)
- CrCl ≤15 mL/min: 100-300 mg/day (QD)
Efficacy Considerations
- Standard gabapentin has demonstrated efficacy in multiple neuropathic pain conditions 3, 5
- Most robust evidence exists for postherpetic neuralgia and diabetic neuropathy 3
- Effective for various pain qualities including burning pain, shooting pain, and allodynia 4, 6
- Improvement typically seen within 1-2 weeks of reaching therapeutic doses
Side Effect Profile
Common side effects for both formulations include:
- Dizziness (19% of patients)
- Somnolence (14%)
- Peripheral edema (7%)
- Gait disturbance (14%) 3
Side effects are typically mild to moderate and often subside within approximately 10 days of treatment initiation 4. Rare cases of gabapentin-induced polyneuropathy have been reported 7.
Special Considerations
- Elderly patients: Start with lower doses (100-300 mg/day) and titrate more slowly 2
- Renal impairment: Requires dose adjustment as noted above 2
- Gabapentin improves sleep scores in addition to pain relief 1
- Regular evaluation of continued benefit is recommended for long-term treatment 2
Conclusion
Based on the available evidence, standard gabapentin (Gabapin) is preferred over gabapentin enacarbil (Gabapin NT) for neuropathic pain due to its established efficacy, extensive clinical evidence, and lower cost. The decision should be guided by the robust clinical evidence supporting standard gabapentin as a first-line treatment for neuropathic pain conditions.