Pregabalin to Gabapentin Conversion Ratio
The recommended conversion ratio when transitioning from pregabalin (Lyrica) to gabapentin is approximately 1:6, meaning 1 mg of pregabalin is roughly equivalent to 6 mg of gabapentin. 1
Conversion Approach
- When converting from pregabalin to gabapentin, a gradual transition is recommended to minimize breakthrough symptoms and adverse effects 1
- The Mayo Clinic recommends a transition method using 50% of the original pregabalin dose plus 50% of the target gabapentin dose for 4 days, especially for patients sensitive to medication changes 1
- Alternatively, an immediate discontinuation of pregabalin with initiation of gabapentin at the next scheduled dose period can be considered in less sensitive patients 2
Dosing Considerations
- For patients on pregabalin 150 mg/day, the equivalent gabapentin dose would be approximately 900 mg/day 2
- For patients on pregabalin 300 mg/day, the equivalent gabapentin dose would be approximately 1800 mg/day 2
- For patients on pregabalin 600 mg/day, the equivalent gabapentin dose would be approximately 3600 mg/day 2
- Due to gabapentin's nonlinear pharmacokinetics, higher doses may have decreased bioavailability compared to pregabalin's linear pharmacokinetics 1
Pharmacokinetic Differences to Consider
- Pregabalin has higher bioavailability (90%) compared to gabapentin (≤60%), which decreases with increasing doses 3, 1
- Pregabalin has a more rapid onset of action due to more efficient gastrointestinal absorption 1
- Gabapentin requires a longer titration period (approximately 2 months) compared to pregabalin (approximately 4 weeks) to reach therapeutic effect 1
- Both medications require dosage adjustments in patients with renal insufficiency 1
Practical Conversion Strategy
- Start with a gabapentin dose that is approximately 6 times the current pregabalin dose 1, 2
- Divide the total daily gabapentin dose into three times daily dosing due to its shorter half-life 4
- For neuropathic pain management, gabapentin doses typically range from 100-1200 mg three times daily 4
- Monitor for breakthrough pain during the transition period, as gabapentin may take longer to reach full therapeutic effect 1, 5
Common Pitfalls to Avoid
- Avoid abrupt discontinuation of pregabalin in patients who have been on high doses for extended periods 1
- Be aware that a higher percentage of patients achieve therapeutic dosing with pregabalin compared to gabapentin (89.3% vs 46.2%), which may affect pain control during transition 5
- Consider that patients may require higher doses of gabapentin to achieve the same analgesic effect as pregabalin 5
- Monitor for changes in opioid requirements, as studies have shown different patterns of opioid use with gabapentin versus pregabalin 5