What are the treatment options for postherpetic neuralgia?

Treatment of Postherpetic Neuralgia

Gabapentin should be your first-line oral pharmacological treatment for postherpetic neuralgia, starting at 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, then titrating up to 1800-3600 mg/day in three divided doses as needed for pain relief. 1, 2

First-Line Treatment Options

Oral Pharmacotherapy

• Gabapentin is recommended as the primary oral agent by the American College of Physicians, with demonstrated efficacy across the 1800-3600 mg/day dose range and no additional benefit shown above 1800 mg/day 1
• FDA-approved studies in 563 PHN patients showed efficacy at all tested doses (1800-3600 mg/day), with pain reduction visible by Week 1 and maintained throughout treatment 2
• Tricyclic antidepressants (TCAs) provide excellent efficacy with an NNT of 2.64, making them highly effective 1
• Nortriptyline is preferred over amitriptyline due to better tolerability with equivalent analgesic benefit, started at 10-25 mg at bedtime and increased every 3-7 days to 25-100 mg at bedtime 1, 3

Topical Treatments

• Topical lidocaine 5% patches provide excellent efficacy (NNT = 2) with minimal systemic absorption, worn for 12-24 hours on affected areas, particularly suitable for elderly patients or those with comorbidities 1
• Capsaicin 8% dermal patch or cream can provide pain relief for at least 12 weeks, though erythema and pain are common side effects that can be mitigated by applying 4% lidocaine for 60 minutes before capsaicin application 1

Second-Line Treatment Options

When Gabapentin Provides Inadequate Response

• Pregabalin should be considered if gabapentin fails, with an NNT of 4.93 and effective dosing typically 150-600 mg/day in two divided doses 1, 4
• FDA studies in PHN patients showed statistically significant pain improvement with pregabalin, with some patients experiencing pain decrease as early as Week 1 4
• Tramadol shows efficacy with an NNT of 4.76 1

Opioid Considerations

• 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 (morphine with gabapentin) may be more effective when single agents fail, allowing lower doses of each medication while providing additive effects 1

Special Population Considerations

Elderly Patients

• Start with lower doses and titrate more slowly in elderly patients 1
• Topical treatments are particularly valuable due to minimal systemic effects 1
• Monitor for medication side effects such as somnolence, dizziness, and mental clouding with gabapentinoids, especially in this population 1

Non-Pharmacological Approaches

• Cognitive behavioral therapy (CBT), hypnosis, and physical/occupational therapy may be beneficial as adjunctive treatments 1
• Transcutaneous electrical nerve stimulation (TENS) is appropriate as a low-risk intervention 5, 6

Critical Pitfalls to Avoid

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
• Avoid medications with high sedation potential when sedation is a concern 1

Interventional Procedures

• Interventional treatments (nerve blocks, radiofrequency, spinal cord stimulation) should be reserved for patients who fail conservative management, as evidence is limited to Level 2 with grade B recommendations 5
• Subcutaneous botulinum toxin A or triamcinolone injection, peripheral nerve stimulation, and stellate ganglion block are recommended first among interventional options if needed 5
• Dorsal root ganglion destruction and intrathecal methylprednisolone should be used with great care due to destructiveness and adverse events 5

Treatment Algorithm

Step 1: Start with gabapentin (titrate as described above) OR topical lidocaine patches for localized pain OR nortriptyline if sedation at bedtime is acceptable 1, 2

Step 2: If inadequate response, switch to pregabalin OR add combination therapy (e.g., gabapentin + morphine at lower doses) 1, 4

Step 3: Consider tramadol or carefully selected opioids if Steps 1-2 fail, weighing risks versus benefits 1

Step 4: Add non-pharmacological approaches (CBT, TENS) at any stage as adjunctive therapy 1, 5

Step 5: Reserve interventional procedures for refractory cases only 5

Reassess periodically, as postherpetic neuralgia may improve over time 1