Treatment Options for Postherpetic Neuralgia
Gabapentin is the recommended first-line oral pharmacological treatment for postherpetic neuralgia (PHN), starting at 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, with titration up to 1800-3600 mg/day as needed for pain relief. 1, 2
First-Line Treatments
Gabapentin should be initiated at 300 mg on day 1,600 mg on day 2, and 900 mg on day 3, with subsequent titration up to 1800 mg/day as needed; clinical studies demonstrated efficacy across doses from 1800-3600 mg/day, but additional benefit above 1800 mg/day was not demonstrated 1, 2
Tricyclic antidepressants (TCAs) have excellent efficacy with a number needed to treat (NNT) of 2.64, with nortriptyline preferred over amitriptyline due to better tolerability with equivalent analgesic benefit 1, 3
Topical lidocaine patches (5%) provide excellent efficacy (NNT = 2) with minimal systemic absorption, making them 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; applying 4% lidocaine for 60 minutes before capsaicin application can mitigate common side effects of erythema and pain 1
Second-Line Treatments
Pregabalin should be considered if patients have an inadequate response to gabapentin, with an NNT of 4.93, and effective doses typically ranging from 150-600 mg/day in two divided doses 1, 4
Serotonin-norepinephrine reuptake inhibitors (SNRIs) may be considered if gabapentin provides inadequate response 1
Opioids (oxycodone, extended-release morphine, methadone) show 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, 3
Tramadol shows efficacy with an NNT of 4.76 and may be considered before stronger opioids 1
Special Considerations for Elderly Patients
For elderly patients, start with lower doses and titrate more slowly, with topical treatments being particularly valuable due to minimal systemic effects 1
Dose adjustment is required for patients with renal impairment; for creatinine clearance 30-59 mL/min, gabapentin dosing should be reduced to 400-1400 mg/day; for 15-29 mL/min, 200-700 mg/day 2
Elderly patients are more likely to have decreased renal function, so dose should be adjusted based on creatinine clearance values 2
Combination Therapy
Combination therapy, such as combining morphine with gabapentin, may be more effective when single agents provide inadequate relief, allowing for lower doses of each medication while providing additive effects 1
When using combination therapy, monitor closely for additive side effects, particularly sedation and dizziness 1
Non-Pharmacological Approaches
Cognitive behavioral therapy (CBT), hypnosis, and physical and occupational therapy are non-pharmacological approaches that may be beneficial for PHN 1
Alpha lipoic acid (ALA) may have a role in multimodal therapy for neuropathic pain management, though studies specifically in PHN are limited 1
Common Pitfalls and Caveats
Lamotrigine is not recommended for PHN due to lack of convincing evidence of efficacy and risk of lamotrigine-associated rash 1
Monitor for medication side effects, especially somnolence, dizziness, and mental clouding with gabapentinoids, particularly in elderly patients 1, 5
The maximum time between gabapentin doses should not exceed 12 hours to maintain therapeutic effect 2
Periodic reassessment of continued therapy is recommended, as PHN may improve over time 1
In randomized controlled trials, gabapentin showed statistically significant reduction in average daily pain scores compared to placebo (from 6.3 to 4.2 points vs. 6.5 to 6.0 points) 5