What is the recommended protocol for converting a patient from Lyrica (pregabalin) to gabapentin?

Protocol for Converting from Pregabalin (Lyrica) to Gabapentin

When converting from pregabalin to gabapentin, a gradual cross-titration approach is recommended with a dose ratio of approximately 1:6 (pregabalin:gabapentin), starting with gabapentin at 300 mg three times daily while tapering pregabalin over 1-2 weeks.

Conversion Ratio and Dosing Principles

• The approximate dose conversion ratio is 1:6 for pregabalin to gabapentin (e.g., 300 mg of pregabalin is roughly equivalent to 1800 mg of gabapentin) 1
• Gabapentin should be initiated at 300 mg three times daily (900 mg/day) and can be titrated up to 1800-3600 mg/day in divided doses 2
• For most patients, efficacy is demonstrated at doses of 1800 mg/day, with limited additional benefit at higher doses 2

Cross-Titration Method

• Begin with 50% of the original pregabalin dose plus 50% of the target gabapentin dose for 4 days 1
• Gradually increase gabapentin while decreasing pregabalin over 1-2 weeks to minimize withdrawal symptoms 1, 3
• For example, when converting from pregabalin 300 mg/day to gabapentin:
  • Days 1-4: Pregabalin 150 mg/day + Gabapentin 900 mg/day (300 mg TID)
  • Days 5-8: Pregabalin 75 mg/day + Gabapentin 1200-1500 mg/day
  • Days 9-14: Discontinue pregabalin + Gabapentin 1800 mg/day (600 mg TID) 1, 2

Dosage Adjustments for Special Populations

• Both medications require dose adjustment in patients with renal impairment 1, 2
• For patients with creatinine clearance 30-59 mL/min, reduce gabapentin to 400-1400 mg/day in divided doses 2
• For patients with creatinine clearance 15-29 mL/min, reduce gabapentin to 200-700 mg/day 2
• Elderly patients may require lower doses due to decreased renal function 2

Monitoring and Management

• Monitor for breakthrough pain during the transition period 1
• Watch for withdrawal symptoms (restlessness, agitation, anxiety, insomnia) if pregabalin is discontinued too rapidly 3, 4
• Assess for common adverse effects including dizziness, somnolence, peripheral edema, and weight gain 5
• Allow adequate trial time - gabapentin may require 2 months or more to achieve full efficacy compared to 4 weeks for pregabalin 1

Important Considerations

• Avoid abrupt discontinuation of pregabalin to prevent withdrawal syndrome, which can include akathisia, anxiety, and flu-like symptoms 3, 4
• Gabapentin has nonlinear pharmacokinetics at higher doses, which may require more frequent dosing compared to pregabalin's linear pharmacokinetics 1
• Gabapentin may be less likely to reach therapeutic levels in clinical practice compared to pregabalin (only 46.2% of gabapentin patients vs. 89.3% of pregabalin patients reached therapeutic doses after 3 prescriptions) 6
• Maximum time between gabapentin doses should not exceed 12 hours to maintain therapeutic effect 2

Common Pitfalls to Avoid

• Attempting too rapid conversion, which may lead to withdrawal symptoms or inadequate pain control 3, 4
• Failing to adjust doses based on renal function 1, 2
• Not providing adequate overlap between medications during transition 1
• Underestimating the total daily dose needed when converting (remember the 1:6 ratio) 1