What is the recommended treatment for a patient with herpetic neuralgia?

Treatment of Herpetic Neuralgia (Postherpetic Neuralgia)

Start with gabapentin 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, then titrate to 1800-3600 mg/day in three divided doses as the first-line oral treatment for postherpetic neuralgia. 1

First-Line Treatment Approach

Topical Therapy (Preferred for Elderly or Localized Pain)

• Lidocaine 5% patches are the ideal first choice, particularly for elderly patients, offering excellent efficacy (NNT = 2) with minimal systemic absorption. 1, 2
• Apply patches for 12-24 hours on affected areas, delivering medication gradually over hours with no systemic side effects. 1
• This approach is especially valuable for patients with comorbidities or those at risk for medication interactions. 1

Oral Gabapentin (First-Line Systemic Therapy)

• The American College of Physicians recommends gabapentin as first-line oral pharmacological treatment. 1
• Dosing schedule: Start 300 mg day 1,600 mg day 2,900 mg day 3, then titrate to 1800-3600 mg/day in three divided doses. 1, 3
• No additional benefit is demonstrated above 1800 mg/day, so avoid unnecessarily high doses. 1
• For elderly patients, start with 100-200 mg/day and titrate more gradually to prevent neurological side effects (somnolence, dizziness, confusion). 2
• Pain reduction typically begins by week 1 and is maintained throughout treatment. 3

Tricyclic Antidepressants (Alternative First-Line)

• Nortriptyline is preferred over amitriptyline, with excellent efficacy (NNT = 2.64) and better tolerability while providing equivalent analgesic benefit. 1, 2, 4
• Start at 10-25 mg at bedtime, increase every 3-7 days to target dose of 50-75 mg at bedtime (maximum 25-100 mg). 1, 4
• Anticholinergic side effects may be dose-limiting, particularly in patients ≥65 years. 1

Second-Line Treatment Options

Pregabalin

• Consider if inadequate response to gabapentin, with NNT of 4.93. 1, 4
• Effective dose range: 150-600 mg/day in two divided doses. 1, 5
• Start with 25-50 mg/day and titrate slowly, especially in older adults. 1
• Doses below 150 mg/day are typically subtherapeutic. 4
• Pain reduction can occur as early as week 1 and persists throughout treatment. 5

High-Concentration Capsaicin

• 8% capsaicin patch provides pain relief for at least 12 weeks with single application. 1, 4
• Apply 4% lidocaine for 60 minutes before capsaicin application to minimize side effects (erythema and pain). 1, 4
• Low-concentration capsaicin 0.075% cream can be applied 3-4 times daily for 6 weeks. 1

SNRIs (Duloxetine or Venlafaxine)

• Consider if gabapentin provides inadequate response. 1
• Start with lower doses and titrate slowly to minimize adverse effects in older adults. 1

Third-Line Treatment Options

Opioids (Use Only After Optimizing First and Second-Line Agents)

• Oxycodone, extended-release morphine, and methadone show efficacy (NNT = 2.67). 1, 2, 4
• Should NOT be used as first-line agents due to risks of pronociception, cognitive impairment, respiratory depression, endocrine/immunological changes, and potential for misuse and addiction. 1, 4
• These risks are particularly concerning in elderly patients. 2, 4

Tramadol

• Shows efficacy with NNT of 4.76 and may have more favorable side effect profile than stronger opioids. 1, 4

Combination Therapy

• Combining morphine with gabapentin may be more effective when single agents provide inadequate relief, allowing lower doses of each medication while providing additive effects. 1, 4

Non-Pharmacological Adjunctive Treatments

• Cognitive behavioral therapy (CBT), hypnosis, and physical/occupational therapy should be incorporated, particularly for severe, refractory cases. 1, 4

Critical Pitfalls to Avoid

Medications to NEVER Use

• Lamotrigine is NOT recommended for postherpetic neuralgia due to lack of convincing evidence of efficacy and risk of lamotrigine-associated rash. 1, 2, 4
• Corticosteroids provide no benefit for established postherpetic neuralgia and expose patients to unnecessary adverse effects including hyperglycemia, osteoporosis, hypertension, and immunosuppression. 1

Dosing Considerations

• Always adjust gabapentin and pregabalin doses based on renal function in elderly patients to prevent toxicity, as these medications are renally excreted. 2, 4
• Monitor closely for neurological side effects (somnolence, dizziness, confusion) that are particularly problematic in older adults. 2, 4
• Periodic reassessment of continued therapy is recommended, as postherpetic neuralgia may improve over time. 1, 4

When to Refer

• If no improvement after 8 weeks of optimized first and second-line therapy, referral to a comprehensive pain rehabilitation center should be considered. 4