Gabapentin to Pregabalin (Lyrica) Conversion Strategy
When converting from gabapentin to pregabalin (Lyrica), use a 6:1 ratio where 600 mg of gabapentin is approximately equivalent to 100 mg of pregabalin, with pregabalin typically dosed at 150-600 mg/day in 2-3 divided doses compared to gabapentin's 900-3600 mg/day in 3 divided doses. 1
Conversion Approach
Step 1: Calculate Equivalent Dose
- Use the 6:1 ratio (gabapentin:pregabalin)
- Example conversions:
- 900 mg gabapentin ≈ 150 mg pregabalin
- 1800 mg gabapentin ≈ 300 mg pregabalin
- 3600 mg gabapentin ≈ 600 mg pregabalin
Step 2: Initiate Pregabalin
- Start at a lower dose than the calculated equivalent
- Begin with 75 mg pregabalin twice daily (150 mg/day) 1, 2
- This "low and slow" approach helps minimize side effects while transitioning
Step 3: Taper Gabapentin While Titrating Pregabalin
- Gradually reduce gabapentin over 1-2 weeks while increasing pregabalin
- Consider asymmetric dosing with larger pregabalin dose in evening to improve tolerability 2
Step 4: Titrate to Effective Dose
- Increase pregabalin by 75-150 mg/day every 3-7 days as needed and tolerated
- Target dose range: 150-600 mg/day (typically 300-450 mg/day for most patients) 1
- Maximum recommended dose: 600 mg/day in divided doses
Key Differences Between Medications
Pregabalin offers several advantages over gabapentin that make the conversion beneficial:
- Higher bioavailability (>90% vs. variable, dose-dependent for gabapentin) 1
- More predictable absorption (not saturable like gabapentin)
- Faster titration period (days vs. weeks) 1
- Fewer daily doses (2-3 times daily vs. 3 times daily) 1
Renal Adjustment Considerations
Both medications require dose adjustment in renal impairment:
For pregabalin in renal impairment 1:
- CrCl ≥60 mL/min: No adjustment needed
- CrCl 30-59 mL/min: Start with 75 mg/day, max 300 mg/day in divided doses
- CrCl 15-29 mL/min: Start with 25-50 mg/day, max 150 mg/day
- CrCl <15 mL/min: Start with 25 mg/day, max 75 mg/day
Monitoring and Side Effect Management
Common adverse effects to monitor:
- Dizziness (27-46% at higher doses) 1
- Somnolence (15-25% at higher doses) 1
- Peripheral edema (more common with pregabalin than with combination therapy) 3
- Weight gain 1, 4
The "low and slow" titration approach is particularly important to minimize these side effects 2. Patients should be advised about potential driving impairment, especially during the transition period.
Clinical Efficacy Considerations
While both medications are effective for neuropathic pain, some evidence suggests that gabapentin may provide superior pain reduction with fewer adverse events in certain patients 5. If pregabalin is ineffective or poorly tolerated, consider returning to gabapentin or exploring other options like tricyclic antidepressants, which some studies suggest may be more effective than pregabalin 4.