Lidocaine Patch for Post-Herpetic Neuralgia Management
Lidocaine 5% patch is recommended as a first-line topical treatment for post-herpetic neuralgia due to its proven efficacy, excellent safety profile, and minimal systemic absorption. 1
Mechanism and Formulation
- Lidocaine patches work by blocking sodium ion channels required for the initiation and conduction of neuronal impulses, resulting in local anesthesia after topical application 2
- Available in two concentrations:
- Over-the-counter 4% concentration
- Prescription 5% strength (more commonly used for PHN) 2
Dosing and Administration
- Apply up to 3 patches to cover the area of greatest pain for 12-24 hours per day 2, 1
- Maximum coverage area: 420 cm² 3
- Patches should be worn for no more than 12 hours in a 24-hour period 2
- Patches can be cut to fit the affected area if needed
Efficacy
- Clinical trials demonstrate significant reduction in pain intensity and increased pain relief compared to vehicle patch 3, 4
- Pain relief begins within 30 minutes of application and can last throughout the 12-hour application period 3
- Approximately 60% of patients report moderate to complete pain relief with lidocaine patches 5
- Effectiveness is maintained regardless of how long the patient has had PHN 5
Safety Profile
- Minimal systemic absorption (highest measured blood lidocaine level: 0.1 μg/ml) 3
- Few drug interactions due to minimal systemic absorption
- Well-tolerated when applied to allodynic skin for 12 hours 3
Adverse Effects
- Most common: mild skin redness or irritation at application site 4
- Application to the head/neck area may be associated with more adverse events compared to trunk or extremities 6
- No significant systemic side effects reported in clinical trials 3, 4
Special Considerations
- Effectiveness varies by anatomic location:
- Equally effective on trunk, head, and extremities
- Better tolerated on trunk and extremities than on head/neck 6
- Effective even in patients with complete loss of nociceptor function in the affected skin area 7
- Can be used as monotherapy or in combination with other agents for PHN 5
Alternative and Adjunctive Therapies
If lidocaine patch provides inadequate relief, consider adding or switching to:
Oral medications:
Other topical options:
- Capsaicin 8% patch (requires pre-treatment with lidocaine) 1
Clinical Pearls
- Start treatment as early as possible in the course of PHN for best results 5
- Allow adequate trial period (3-4 weeks) before declaring treatment failure 1
- Consider lidocaine patch as first-line therapy due to its favorable safety profile, especially in elderly patients who may not tolerate systemic medications 1, 5
- For patients with refractory pain, combination therapy with oral medications may provide better relief than monotherapy 1