What are the treatment options for postherpetic neuralgia (PHN) or post-shingle pain?

Treatment of Post-Shingle Pain (Postherpetic Neuralgia)

Start with gabapentin as first-line oral therapy, beginning at 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 for pain relief. 1, 2

First-Line Treatment Options

Oral Medications

• Gabapentin is the recommended first-line oral agent, with FDA-approved efficacy demonstrated across doses of 1800-3600 mg/day, though no additional benefit has been shown above 1800 mg/day 1, 2

  • The maximum time between doses should not exceed 12 hours 2
  • In clinical trials, gabapentin reduced average daily pain scores from 6.3 to 4.2 points (vs. 6.5 to 6.0 with placebo), with significant improvements in sleep interference and quality of life 3
  • Common side effects include somnolence, dizziness, ataxia, and peripheral edema, particularly in elderly patients 1, 3

• Tricyclic antidepressants (TCAs) provide excellent efficacy with an NNT of 2.64, making them highly effective alternatives to gabapentin 1

  • Nortriptyline is preferred over amitriptyline due to better tolerability with equivalent analgesic benefit 1
  • Start at 10-25 mg at bedtime and increase every 3-7 days to a final dose of 25-100 mg at bedtime as tolerated 1
  • TCAs are effective in approximately 50% of patients but are frequently contraindicated or poorly tolerated in elderly patients 4

Topical Medications

• Topical lidocaine 5% patches provide excellent efficacy (NNT = 2) with minimal systemic absorption, making them particularly suitable for elderly patients or those with comorbidities 1

  • Can be worn for 12-24 hours on affected areas, delivering medication gradually over hours 1
  • Especially appropriate for patients with localized pain areas 1

• Capsaicin 8% dermal patch or cream can provide pain relief for at least 12 weeks 1

  • Common side effects include erythema and pain, which can be mitigated by applying 4% lidocaine for 60 minutes before capsaicin application 1

Second-Line Treatment Options

• Pregabalin should be considered if gabapentin provides inadequate response, with an NNT of 4.93 1, 5

  • Effective doses typically range from 150-600 mg/day in two divided doses 1
  • FDA-approved for postherpetic neuralgia with demonstrated efficacy in multiple trials 5
  • Some patients experienced pain decrease as early as Week 1 that persisted throughout treatment 5

• Tramadol shows efficacy with an NNT of 4.76 and can be used as a second-line option 1

• Opioids (oxycodone, extended-release morphine, methadone) show strong efficacy (NNT = 2.67) but 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

Combination Therapy

• When single agents provide inadequate relief, combination therapy such as morphine with gabapentin may be more effective, allowing for lower doses of each medication while providing additive effects 1

Special Considerations for Elderly Patients

• Start with lower doses and titrate more slowly in elderly patients, with topical treatments being particularly valuable due to minimal systemic effects 1
• Adjust gabapentin dosing based on creatinine clearance in patients with renal impairment 2:
  • For CLcr ≥60 mL/min: 900-3600 mg/day in three divided doses
  • For CLcr 30-59 mL/min: 400-1400 mg/day in two divided doses
  • For CLcr 15-29 mL/min: 200-700 mg/day as single daily dose
  • For CLcr <15 mL/min: 100-300 mg/day as single daily dose
  • Hemodialysis patients require supplemental post-dialysis dosing 2

Non-Pharmacological Approaches

• Cognitive behavioral therapy (CBT), hypnosis, and physical/occupational therapy may be beneficial as adjunctive treatments 1

What NOT to Use

• Lamotrigine is NOT recommended for PHN due to lack of convincing evidence of efficacy and risk of lamotrigine-associated rash 1
• Carbamazepine is of little or no value in established postherpetic neuralgia 6

Common Pitfalls

• Monitor for medication side effects, particularly somnolence, dizziness, and mental clouding with gabapentinoids in elderly patients 1
• Ensure adequate trial duration - if tricyclics fail to provide relief within 8 weeks, specialist treatment should be considered 6
• Reassess therapy periodically, as postherpetic neuralgia may improve over time and some patients may not require indefinite treatment 1