What is the proper conversion protocol from gabapentin to Lyrica (pregabalin)?

Gabapentin to Pregabalin Conversion

Use a gradual transition method: administer 50% of the original gabapentin dose plus 50% of the target pregabalin dose for 4 days, particularly for patients sensitive to medication changes or at risk for breakthrough symptoms. 1

Conversion Protocol

Step 1: Calculate Target Pregabalin Dose

• Start pregabalin at 50 mg three times daily or 75 mg twice daily for patients on lower gabapentin doses 1
• For patients transitioning from higher gabapentin doses (≥1800 mg/day), start pregabalin at 150 mg/day in 2-3 divided doses 1
• The typical therapeutic range for pregabalin is 100-600 mg/day divided in 2-3 doses 2

Step 2: Execute the Transition

• Overlap period (4 days): Give 50% of current gabapentin dose + 50% of target pregabalin dose simultaneously 1
• After 4 days, discontinue gabapentin completely and continue pregabalin at full target dose 1
• Critical caveat: Avoid abrupt discontinuation of gabapentin in patients on high doses for extended periods 1

Step 3: Titration Schedule for Pregabalin

• Increase to 300 mg/day after 3-7 days 1
• Then increase by 150 mg/day every 3-7 days as tolerated 1
• Maximum recommended dose is 600 mg/day (200 mg three times daily or 300 mg twice daily) 1
• Higher doses (>300 mg/day) are not consistently more effective but have more adverse effects 1

Key Pharmacologic Differences

Pregabalin has linear pharmacokinetics, making dosing more straightforward than gabapentin's nonlinear kinetics. 1 This means:

• Pregabalin provides more predictable dose-response relationships 1
• More efficient GI absorption allows pregabalin to provide analgesia more quickly than gabapentin 1
• An adequate trial of pregabalin requires approximately 4 weeks, compared to 2 months or more for gabapentin 1

Renal Dosing Adjustments

Both medications require mandatory dosage reduction in patients with renal insufficiency. 1

• Adjust dosages according to creatinine clearance for both medications 1
• Pregabalin, like gabapentin, is eliminated unchanged in urine 3
• Dose reduction is required even with moderate renal failure (creatinine clearance <60 mL/min) 3

Monitoring During Transition

Monitor closely for common adverse effects including somnolence, dizziness, and mental confusion during the transition period. 1

• These effects are typically dose-dependent and often transient 4
• Elderly patients are at particular risk for weight gain and peripheral edema with both medications 3
• Visual field restriction has been reported with pregabalin in clinical trials 3

Common Pitfalls to Avoid

• Never abruptly switch without overlap in patients on high gabapentin doses (≥1800 mg/day) - this risks breakthrough symptoms and withdrawal 1
• Do not rush pregabalin titration - allow 3-7 days between dose increases 1
• Avoid exceeding 600 mg/day pregabalin - higher doses increase adverse effects without consistent efficacy gains 1
• Do not declare treatment failure before 4 weeks - pregabalin requires adequate time to reach therapeutic effect 1
• Never forget renal function assessment - both drugs require dose adjustment based on creatinine clearance 1, 3