What is the preferred treatment between Lyrica (pregabalin) and gabapentin for postherpetic neuralgia?

Pregabalin vs Gabapentin for Postherpetic Neuralgia

Gabapentin should be considered the first-line treatment for postherpetic neuralgia over pregabalin due to its established efficacy, favorable safety profile, and extensive clinical evidence. 1, 2

First-Line Treatment Options

• Gabapentin is recommended as the first-line oral pharmacological treatment for postherpetic neuralgia (PHN) with a recommended starting dose of 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, titrating up to 1800-3600 mg/day as needed for pain relief 2, 3
• Gabapentin demonstrated significant efficacy in reducing pain scores in multiple randomized controlled trials, with pain reduction observed as early as week 1 of treatment 3, 4, 5
• For elderly patients or those with renal impairment, a lower starting dose of 100-200 mg/day is appropriate, with slower titration to minimize side effects 1, 6
• The number needed to treat (NNT) for gabapentin in PHN is 4.39, indicating good clinical efficacy 1

Second-Line Treatment Options

• Pregabalin should be considered if patients have an inadequate response to gabapentin, with an NNT of 4.93 1, 2
• Pregabalin offers some pharmacokinetic advantages over gabapentin, including more rapid titration and potentially easier dosing (twice daily versus three times daily for gabapentin) 1, 7
• The effective pregabalin dose typically ranges from 150-600 mg/day in two divided doses, compared to 900-3600 mg/day in three divided doses for gabapentin 1, 8
• Pregabalin achieved a faster onset of pain relief than placebo in clinical trials, with median times to onset of 1.5-3.5 days 7

Comparative Considerations

• Both medications work through similar mechanisms, binding to alpha2-delta subunits of voltage-gated calcium channels 7, 9
• Both medications have similar side effect profiles, with dizziness, somnolence, and peripheral edema being commonly reported 8, 3, 7
• In elderly patients, both medications require careful dose titration starting with lower doses (gabapentin 100-200 mg/day or pregabalin 25-50 mg/day) 1, 2
• Neither medication has demonstrated clear superiority over the other in head-to-head trials for PHN, but gabapentin has more extensive clinical evidence supporting its use 1, 2

Alternative Treatment Options

• Tricyclic antidepressants have excellent efficacy for PHN with an NNT of 2.64, making them highly effective alternatives 1, 2
• Topical lidocaine patches (5%) provide excellent efficacy (NNT = 2) with minimal systemic absorption, making them particularly suitable for elderly patients or those with comorbidities 1, 2
• Capsaicin, available as an 8% dermal patch or cream, can provide pain relief for at least 12 weeks 2

Common Pitfalls and Caveats

• Side effects such as somnolence, dizziness, and mental clouding are common with both gabapentin and pregabalin, particularly in older adults 1, 8, 3
• Renal impairment requires dose adjustment for both medications 1, 8
• Abrupt discontinuation of either medication should be avoided; gradual tapering is recommended 8, 3
• Opioid analgesics should not be prescribed as first-line agents for PHN due to risks of pronociception, cognitive impairment, respiratory depression, and potential for misuse 1
• Lamotrigine is not recommended for PHN due to lack of convincing evidence of efficacy 1

Dosing Recommendations

• For gabapentin: Start with 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, divided into three daily doses, then titrate to 1800-3600 mg/day as needed 2, 3
• For pregabalin: Start with 25-50 mg twice daily (lower doses for elderly or those with renal impairment), then titrate to 150-600 mg/day in two divided doses 1, 8
• In elderly patients, consider starting with gabapentin 100-200 mg/day or pregabalin 25 mg/day and titrate more slowly 1, 6