How do you transition a patient from gabapentin to pregabalin?

Transitioning from Gabapentin to Pregabalin

When transitioning a patient from gabapentin to pregabalin, you can use either an immediate discontinuation approach with initiation of pregabalin at the next scheduled dose, or a gradual transition with 4 days of 50% gabapentin and 50% pregabalin before complete conversion. 1

Conversion Approaches

Immediate Discontinuation Method

• Discontinue gabapentin completely and start pregabalin at the next scheduled dose time 1
• Use the following dose equivalence:
  • Gabapentin 900 mg/day → Pregabalin 150 mg/day 1
  • Gabapentin 1800 mg/day → Pregabalin 300 mg/day 1
  • Gabapentin 3600 mg/day → Pregabalin 600 mg/day 1
• Pharmacokinetic simulations show this approach results in comparable drug exposure with minimal fluctuations 1

Gradual Transition Method

• Administer 50% of the original gabapentin dose plus 50% of the target pregabalin dose for 4 days 1
• After 4 days, discontinue gabapentin completely and continue with the full pregabalin dose 1
• This approach may be preferred for patients who are sensitive to medication changes or at risk for breakthrough symptoms 2

Dosing Considerations

Starting Pregabalin

• Begin with 50 mg three times daily or 75 mg twice daily 2
• For patients transitioning from higher gabapentin doses, consider starting at 150 mg/day in 2-3 divided doses 2, 3
• Use a "low and slow" approach to minimize side effects, especially in elderly patients or those with renal impairment 3

Titration Schedule

• Increase to 300 mg/day after 3-7 days, then by 150 mg/day every 3-7 days as tolerated 2
• Consider "asymmetric dosing" with larger doses in the evening to improve tolerability 3
• Maximum recommended dose is 600 mg/day (200 mg three times daily or 300 mg twice daily) 2
• Note that higher pregabalin doses (>300 mg/day) are not consistently more effective but have more adverse effects 2

Special Considerations

Renal Function

• Both medications require dosage reduction in patients with renal insufficiency 2
• Adjust dosages according to creatinine clearance for both medications 2
• Pregabalin is eliminated unchanged in urine (98%), so dose reduction is needed even with moderate renal impairment (CrCl <60 ml/min) 4

Side Effect Management

• Monitor for common side effects: dizziness (23.1%), drowsiness (14.6%), and peripheral edema (10.4%) 5
• Side effects are dose-dependent and can often be managed with dose reduction without discontinuing therapy 5
• Educate patients about expected timeline for side effects and their likely resolution 3

Pharmacokinetic Advantages of Pregabalin

• Pregabalin has linear pharmacokinetics, making dosing more straightforward than gabapentin's nonlinear kinetics 2
• Pregabalin may provide analgesia more quickly than gabapentin due to more efficient GI absorption 2
• An adequate trial of pregabalin requires approximately 4 weeks, compared to 2 months or more for gabapentin 2

Common Pitfalls to Avoid

• Avoid underdosing: Many patients are treated with suboptimal pregabalin doses due to prescriber unfamiliarity or concerns about side effects 3
• Avoid abrupt discontinuation of either medication in patients who have been on high doses for extended periods 2
• Do not expect complete interchangeability: Some patients with pregabalin use disorder experienced intense craving and distress when switched to gabapentin, suggesting the medications are not perfectly interchangeable 6
• Avoid assuming equivalent efficacy for all conditions: While both medications work for neuropathic pain, their efficacy may vary by specific condition 4