What alternatives to gabapentin (neurontin) can be used to treat postherpetic neuralgia in a 50-year-old patient with dried shingles?

Treatment Alternatives to Gabapentin for Postherpetic Neuralgia

For a 50-year-old patient with postherpetic neuralgia who cannot use gabapentin, start with topical lidocaine 5% patches as first-line therapy, which provides excellent pain relief (NNT = 2) with minimal systemic absorption, making it ideal for this age group. 1

First-Line Topical Treatments (Start Here)

Topical therapies should be prioritized due to their high safety profile and minimal systemic effects:

• Lidocaine 5% patches can be worn for 12-24 hours on affected areas, delivering medication gradually with excellent efficacy (NNT = 2) and minimal systemic absorption 2, 1
• High-concentration capsaicin 8% patch provides sustained pain relief for up to 12 weeks from a single 30-60 minute application under medical supervision 1, 3
  • Pre-treat with topical lidocaine 4% for 60 minutes before capsaicin application to reduce burning sensation 1, 3
  • Warn patients about initial burning/erythema that typically resolves after several days 3
  • Consider prescribing short-acting analgesics (acetaminophen or short-acting opioids) for use during and up to 7 days post-application 3
• Low-concentration capsaicin 0.075% cream can be applied 3-4 times daily for 6 weeks, with moderate evidence supporting efficacy 2, 3

Second-Line Oral Medications (If Topicals Insufficient)

If topical treatments provide inadequate relief, proceed to oral medications:

Tricyclic Antidepressants (Highly Effective)

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

Pregabalin (Alternative Gabapentinoid)

• Pregabalin may be effective if the patient failed gabapentin due to different pharmacokinetics allowing easier titration, though some patients respond to one but not the other 2, 1
• Start with 25-50 mg/day and titrate to effective dose of 150-600 mg/day in two divided doses (NNT = 4.93) 2, 5
• FDA-approved for postherpetic neuralgia with demonstrated efficacy in multiple controlled trials 5
• Monitor for somnolence, dizziness, and mental clouding, especially in older patients 2

SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)

• Duloxetine is supported by two high-quality studies and five medium-quality studies for neuropathic pain 2
• Venlafaxine is supported by one high-quality study for neuropathic pain 2
• Start with lower doses and titrate slowly to minimize adverse effects in older adults 2

Third-Line Options (When First and Second-Line Fail)

Opioids (Use With Extreme Caution)

• Opioids show efficacy (NNT = 2.67) but should NOT be first-line due to risks of pronociception, cognitive impairment, respiratory depression, endocrine/immunological changes, and potential for misuse and addiction 1
• Options include oxycodone, extended-release morphine, and methadone 1
• Tramadol has lower abuse potential with NNT of 4.76 1

Combination Therapy

• Combining morphine with pregabalin (or another first-line agent) may be more effective when single agents provide inadequate relief, allowing lower doses of each medication while providing additive effects 1

Treatment Algorithm

1. Start with topical lidocaine 5% patches for 2-4 weeks 1, 4
2. If inadequate response, add or switch to high-concentration capsaicin 8% patch (can repeat every 90 days) 1, 3
3. If topicals insufficient, add nortriptyline starting at 10-25 mg at bedtime, titrating to 25-100 mg 1, 4
4. If still inadequate, consider pregabalin 25-50 mg/day titrating to 150-600 mg/day in divided doses 2, 1, 5
5. If monotherapy fails, use combination therapy (e.g., topical + oral agent) 1
6. Reserve opioids for refractory cases only and avoid as first-line 1

Critical Pitfalls to Avoid

• Do NOT use lamotrigine - it lacks convincing evidence of efficacy in PHN and carries risk of serious rash 1, 4
• Do NOT skip lidocaine pretreatment before high-concentration capsaicin application - this is critical for tolerability 1, 3
• Do NOT start with high doses in older adults - begin with lowest doses and titrate slowly to minimize neurological side effects (somnolence, dizziness, confusion) 2, 4
• Do NOT use opioids as first-line therapy despite their excellent NNT, due to significant safety concerns 1
• Do NOT expect immediate results with capsaicin - counsel patients that consistent use over 4-6 weeks is required for efficacy assessment 3

Non-Pharmacological Adjuncts

• Cognitive behavioral therapy (CBT), hypnosis, and physical/occupational therapy may provide additional benefit as part of multimodal approach 1