What dose of Lyrica (pregabalin) is equivalent to 100mg of Gabapentin?

Pregabalin-Gabapentin Dose Equivalency

There is no established direct dose conversion ratio between pregabalin (Lyrica) and gabapentin, but pregabalin is approximately 3-6 times more potent than gabapentin on a milligram basis, meaning 100mg of gabapentin would roughly correspond to 15-30mg of pregabalin. However, this is not a clinically validated conversion, and switching between these medications requires independent titration rather than direct substitution.

Why Direct Conversion Is Not Recommended

The pharmacokinetic profiles of these medications differ substantially, making direct dose conversion inappropriate:

• Pregabalin has linear pharmacokinetics with ~90% bioavailability, allowing for more predictable dosing 1, 2
• Gabapentin has nonlinear, saturable absorption, making dose escalation less predictable and requiring three-times-daily dosing 3, 1
• Despite binding to the same α2δ subunit of voltage-gated calcium channels, their distinct absorption characteristics prevent reliable dose equivalency calculations 1

Clinical Approach to Switching Medications

If switching from gabapentin to pregabalin, you must start pregabalin at its standard initial dose and titrate independently:

Starting Pregabalin After Gabapentin

• Begin pregabalin at 50mg three times daily or 75mg twice daily (150mg/day total), regardless of the gabapentin dose the patient was receiving 4, 1
• Titrate to 100mg three times daily (300mg/day) as the typical effective dose, with maximum of 600mg/day in divided doses 4
• Pregabalin is more efficiently absorbed through the GI tract than gabapentin, allowing for potentially lower total daily doses 4

Tapering Considerations

• Never abruptly discontinue either medication—taper gabapentin gradually over at least 1 week while initiating pregabalin 3, 1
• Overlap the medications during transition to avoid withdrawal symptoms and maintain pain control 1

Relative Potency Context

While not a conversion formula, understanding relative efficacy helps frame expectations:

• Pregabalin 300mg/day demonstrates similar efficacy to gabapentin 1800-3600mg/day for neuropathic pain conditions 4, 1
• This suggests pregabalin is roughly 6-12 times more potent on a milligram basis at therapeutic doses
• Higher pregabalin doses (>300mg/day) are not consistently more effective and cause more adverse effects 1

Critical Pitfalls to Avoid

• Do not calculate a mathematical conversion (e.g., dividing gabapentin dose by 6)—this is not evidence-based and risks under- or over-dosing 1
• Both medications require dose adjustment in renal impairment, as they are eliminated unchanged by the kidneys 4, 3, 1
• In elderly or medically frail patients, use slower titration for either medication to reduce fall risk from dizziness 3, 1
• Allow 2 months for full therapeutic trial before declaring treatment failure, as efficacy develops gradually 3, 5

When Combination Therapy May Be Considered

In refractory cases, gabapentin and pregabalin can be used together, as they have been noted to have synergistic effects without clinically significant pharmacokinetic interactions 6. This approach allows dose reduction of individual agents to minimize side effects while enhancing therapeutic response 6.