What is the recommended dosing strategy to convert a patient from gabapentin (Neurontin) 1200mg per day to Lyrica (Pregabalin)?

Gabapentin to Pregabalin Conversion

For a patient taking gabapentin 1200 mg/day (600 mg, 300 mg, 300 mg), convert to pregabalin 150 mg/day divided into 75 mg twice daily or 50 mg three times daily, using an approximate 6:1 conversion ratio. 1

Conversion Rationale

• Pregabalin has linear pharmacokinetics compared to gabapentin's nonlinear, saturable absorption, making pregabalin dosing more straightforward and predictable 1
• The typical conversion ratio is approximately 6:1 (gabapentin:pregabalin), meaning 1200 mg/day of gabapentin converts to approximately 150-200 mg/day of pregabalin 1
• Pregabalin 150 mg/day has demonstrated efficacy in clinical trials for neuropathic pain conditions, making this an appropriate starting dose after conversion 1, 2

Specific Conversion Protocol

• Day 1: Begin pregabalin 75 mg twice daily (total 150 mg/day) while discontinuing gabapentin 1
• Alternative dosing: Pregabalin 50 mg three times daily (total 150 mg/day) can be used if the patient prefers more frequent dosing 1
• Titration if needed: After 1 week, the dose can be increased to 300 mg/day (150 mg twice daily) if pain control is inadequate, as higher doses (>300 mg/day) are not consistently more effective and cause more adverse effects 1

Critical Considerations Before Conversion

• Renal function assessment is mandatory before initiating pregabalin, as both gabapentin and pregabalin are eliminated unchanged by the kidneys and require dose reduction in renal impairment 1
• For creatinine clearance <60 mL/min, dose adjustments are required for both medications 3, 1
• In elderly patients, start at the lower end of the dosing range and monitor closely for dizziness and sedation 1

Expected Adverse Effects

• Both medications produce similar dose-dependent side effects including dizziness, somnolence, peripheral edema, and dry mouth 1, 2
• With pregabalin 150 mg/day, expect dizziness (23%), drowsiness (15%), and peripheral edema (10%) 2
• These effects are typically mild to moderate and often subside within approximately 10 days 3, 4
• Adverse effects can be managed by dose reduction rather than discontinuation 2

Efficacy Timeline

• Allow 3-4 weeks at the target dose to properly evaluate efficacy, as neuropathic pain relief develops gradually 3
• Pregabalin may provide faster onset of action compared to gabapentin due to its linear pharmacokinetics 1
• In clinical trials, 33-50% of patients achieved at least 50% pain reduction with pregabalin 150-600 mg/day for neuropathic pain 5, 2

Common Pitfalls to Avoid

• Do not abruptly discontinue gabapentin—however, at the relatively low dose of 1200 mg/day, direct switch to pregabalin is generally safe without a taper 1
• Do not exceed 300 mg/day pregabalin initially, as higher doses are not consistently more effective and increase adverse effects 1
• Do not fail to assess renal function before conversion, as this is non-negotiable for safe dosing 3, 1
• Do not rush to declare treatment failure—allow the full 3-4 week trial period at the target dose 3