Treatment and Prevention Strategies for PHN

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PHN is uncommon among individuals younger than age 40.
PHN is uncommon among individuals younger than age 40.

Postherpetic neuralgia (PHN) is a condition characterized by debilitating neuropathic pain that arises as a complication of herpes zoster infection (shingles).

According to the Centers for Disease Control and Prevention (CDC), approximately 1 million cases of shingles occur in the United States annually, and nearly half of all cases occur in people aged ≥60. Of these, about 20% will develop postherpetic neuralgia. The condition is uncommon among individuals <40 years of age. However, PHN is more likely to develop after a severe shingles outbreak that had a notable prodrome.1, 2

Despite the availability of shingles immunization and treatment options, the incidence of postherpetic neuralgia is increasing. In addition, treating PHN can be complicated by polypharmacy, adverse events, drug-drug interactions, and patient comorbidities. Therefore, optimal management of PHN requires individual-based treatment approaches that address underlying comorbid conditions and provide pain relief with minimal adverse effects.2

Current Treatment and Prevention Recommendations

Jamie S. Massengill of JSM Medical in Edmond, OK, and John L. Kittredge of Michiana Spine, Sports and Occupational Rehab in Mishawaka, IN, outlined current treatment and prevention strategies for postherpetic neuralgia in a review article published in the Journal of Pain Research

Treating PHN involves addressing the acute illness and accompanying pain syndrome. The acute shingles outbreak is commonly treated within 72 hours of rash onset with antiviral therapies including acyclovir (Zovirax; GlaxoSmithKline), famciclovir (Famvir; Novartis) or valacyclovir (Valtrex; GlaxoSmithKline). In addition, according to Massengill, corticosteroids are often used early in a shingles infection but have limited evidence for preventing the development of postherpetic neuralgia.

The pain syndrome of PHN is most commonly treated with oral and topical medications.  Orally administered gabapentinoids include gastroretentive gabapentin (Gralise; Depomed), extended-release gabapentin enacarbil (Horizant; XenoPort), immediate-release gabapentin (Neurontin; Pfizer), and pregabalin (Lyrica; Pfizer). Topical treatments include the lidocaine 5% patch (Lidoderm; Endo) and the capsaicin 8% patch (Qutenza; Acorda Therapeutics).2

“Gabapentinoids and lidocaine patch are first-line approved treatments. Capsaicin is a second-line treatment approved by the FDA,” said Massengill. Furthermore, “Tertiary treatments can include short-acting opioids or nonsteroidal anti-inflammatory drugs (NSAIDs). However, these tertiary treatments should be considered only when other options have been exhausted and should only be used for short periods of time.”

The primary focus of prevention is vaccination, which includes varicella vaccination in childhood and live zoster vaccine (Zostavax, Merck) among adults aged ≥50.
 

Practical Considerations for Postherpetic Neuralgia Management

“Practical considerations should include prevention of shingles followed by, should one be subjected to shingles, a focus to shorten the course of the illness through reduced viral replication and rapid deployment of various treatment strategies to combat the ensuing pain syndrome,” said Massengill.

Insurance coverage and pharmacy benefit managers commonly hinder drug choice. “All medical providers are trained in the evidenced-based approach to the treatment of this and any other condition. However, the black cloud of insurance denials and road blocks prevent best practice approaches in many cases,” said Massengill. In addition, other factors including drug cost, route of administration, potential adverse effects, method of drug metabolism, possible drug-drug interactions, and drug dosing regimens may impact drug choice.

Conclusion

Overall, postherptic neuralgia is a widely variable condition that ranges from mild to severe and prolonged. Treatment plans need to be individualized and focus on shingles outbreak prevention followed by treatment with medication at the lowest possible doses with maximum benefit and fewest adverse effects.

References:

  1. Centers for Disease Control and Prevention (CDC). Shingles (Herpes Zoster). Available at:http://www.cdc.gov/shingles/about/overview.html. Accessed: June 17, 2014. 
  2. Massengill JS, Kittredge JL. Practical considerations in the pharmacological treatment of postherpetic neuralgia for the primary care provider. J Pain Research. 2014 (7): 125-132.
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