What is the Lyrica (pregabalin) equivalent of 600mg gabapentin (Gabapentin) twice a day (BID)?

Pregabalin Equivalent for 600mg Gabapentin BID

The pregabalin equivalent of 600mg gabapentin BID (1200mg/day) is approximately 150mg pregabalin per day (75mg BID). This conversion is based on clinical guidelines for neuropathic pain management 1.

Conversion Rationale

When converting between gabapentin and pregabalin, several pharmacological differences must be considered:

• Bioavailability differences: Pregabalin has >90% bioavailability regardless of dose, while gabapentin's bioavailability decreases with increasing doses (60% at lower doses to 33% at higher doses) 2
• Absorption characteristics: Gabapentin has saturable (zero-order) absorption, while pregabalin has linear (first-order) absorption, making pregabalin's pharmacokinetics more predictable 2
• Potency ratio: Pregabalin is approximately 6 times more potent than gabapentin based on clinical efficacy data 1, 3

Dosing Guidelines

For neuropathic pain management:

• Starting pregabalin dose: 50-75mg BID (100-150mg/day) 1
• Target pregabalin dose: 300-600mg/day in divided doses 3, 1
• Titration schedule: Increase gradually based on response and tolerability

Clinical Considerations

1. Efficacy comparison:

   • For neuropathic pain, pregabalin 450mg/day appears to provide comparable pain reduction to the maximum effect of gabapentin 2
   • Pregabalin may have a more predictable dose-response relationship due to its linear pharmacokinetics 2

2. Administration advantages of pregabalin:

   • Faster absorption (peak plasma concentration within 1 hour vs. 3-4 hours for gabapentin) 2
   • More consistent bioavailability across dosing range 2
   • May be administered once daily using controlled-release formulation 4

3. Side effect profile:

   • Both medications share similar adverse effects including:
     • Dizziness and somnolence (most common)
     • Peripheral edema
     • Weight gain
     • Dry mouth
   • Side effects tend to be dose-dependent and often transient 3, 1

Renal Adjustment Considerations

Both medications require dose adjustment in renal impairment:

• For pregabalin, reduce dose by approximately 50% in moderate to severe renal impairment 1
• For patients with creatinine clearance <60 ml/min, dose adjustments are necessary for both medications 1, 5

Important Cautions

• Visual field restriction has been reported with pregabalin in clinical trials 5
• Neither medication should be abruptly discontinued; taper gradually over at least one week
• While some clinicians have used these medications in combination for refractory cases 6, this practice is not supported by major guidelines and should be approached with caution

When converting from gabapentin 600mg BID to pregabalin, start with 75mg BID and adjust based on clinical response and tolerability.