What are the treatment options for postherpetic neuralgia?

Treatment for Postherpetic Neuralgia

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

First-Line Treatment Options

Oral Pharmacotherapy

• Gabapentin is the recommended first-line oral agent per the American College of Physicians, with demonstrated efficacy across the 1800-3600 mg/day dose range and no additional benefit above 1800 mg/day 1
• The FDA-approved dosing for postherpetic neuralgia involves rapid titration over 3 days to 900 mg/day, then further increases in 600-1200 mg/day increments at 3-7 day intervals to reach the target dose 2
• Pain reduction typically begins by Week 1 and is maintained throughout treatment 2
• For elderly patients, start with 100-200 mg/day and titrate more gradually to minimize side effects like somnolence, dizziness, and mental clouding 3

Topical Treatments (Particularly Valuable for Elderly)

• The 5% lidocaine patch is the ideal first choice for elderly patients, offering excellent efficacy (NNT = 2) with minimal systemic absorption, worn for 12-24 hours on affected areas 1, 3
• The American Geriatrics Society specifically recommends topical lidocaine for older adults or those with comorbidities due to the lack of systemic effects 3
• Capsaicin 8% dermal patch provides pain relief for at least 12 weeks; apply 4% lidocaine for 60 minutes before capsaicin application to mitigate erythema and pain 1, 3

Tricyclic Antidepressants

• Nortriptyline is preferred over amitriptyline with equivalent analgesic benefit (NNT = 2.64) but superior tolerability 1, 4, 5
• Start at 10-25 mg at bedtime, increase every 3-7 days to a final dose of 25-100 mg at bedtime 4
• In elderly patients, start with 10 mg and titrate more slowly 4
• Treatment may need to continue indefinitely until pain resolves, as postherpetic neuralgia can persist for months to years 4

Second-Line Treatment Options

When Gabapentin Provides Inadequate Response

• Pregabalin is the next option with an NNT of 4.93, dosed at 150-600 mg/day in two divided doses 1
• FDA approval supports pregabalin for postherpetic neuralgia with demonstrated efficacy in multiple trials 6
• Pain reduction typically begins by Week 1 and persists throughout treatment 6
• Adjust doses based on renal function: patients with creatinine clearance 30-60 mL/min require lower doses and tolerate pregabalin less well than those with clearance >60 mL/min 6

Opioid Therapy (Use with Caution)

• Opioids (oxycodone, extended-release morphine, methadone) show excellent efficacy (NNT = 2.67) but should not be first-line agents due to risks of pronociception, cognitive impairment, respiratory depression, endocrine/immunological changes, and potential for misuse and addiction 1, 3
• Tramadol has an NNT of 4.76 and may be considered 1
• Combination therapy (morphine with gabapentin) may be more effective when single agents fail, allowing lower doses of each medication with additive effects 1, 3

Non-Pharmacological Approaches

• Cognitive behavioral therapy, hypnosis, and physical/occupational therapy may provide benefit 1
• Electroacupuncture and osteopathic manipulative treatment show efficacy, particularly for intractable cases 7
• Peripheral nerve stimulation can be considered for refractory cases with persistent intractable pain after conservative management fails 8

Critical Pitfalls to Avoid

Medications to Avoid

• Do not use lamotrigine for postherpetic neuralgia—the American College of Physicians states there is lack of convincing evidence of efficacy and risk of lamotrigine-associated rash 1, 3

Monitoring Considerations

• Always adjust doses based on renal function in elderly patients to prevent toxicity 3
• Monitor closely for neurological side effects (somnolence, dizziness, confusion) that are particularly problematic in older adults 1
• Reassess therapy periodically, as postherpetic neuralgia may improve over time 1

Treatment Algorithm

Step 1: For localized pain in elderly or those with comorbidities, start with 5% lidocaine patch 3

Step 2: If topical therapy insufficient or pain is widespread, add gabapentin with rapid titration (or slow titration in elderly) to 1800-3600 mg/day 1, 3

Step 3: If gabapentin fails or is not tolerated, switch to nortriptyline 10-25 mg at bedtime, titrating to 25-100 mg 4

Step 4: If still inadequate, consider pregabalin 150-600 mg/day in divided doses (adjust for renal function) 1, 6

Step 5: For refractory cases, consider combination therapy (gabapentin + morphine) or interventional approaches 1, 3