Postherpetic Neuralgia: Current Evidence on the Topical Film-Forming Spray with Bupivacaine Hydrochloride and a Review of Available Treatment Strategies

Abstract

Purpose of Review This is a comprehensive review of the literature about the use of bupivacaine hydrochloride for the treatment of post-herpetic neuralgia (PHN). It briefly reviews the background, biology, diagnosis and conventional treatment for PHN, and then introduces and compares the recent evidence for the use of topical bupivacaine. Recent Findings PHN is defined by pain lasting 90 days or more after the initial presentation of herpes zoster (“Shingles”, HZ) rash and is the most common complication of this disease. A product of re-activation of the Varicella-Zoster virus (VZV), HZ is diagnosed more than 1 million times annually in the United States. Approximately 20% of patients with HZ will experience PHN and will continue to suffer intermittent neuropathic symptoms, including itching and pain, that is sharp, stabbing, throbbing or burning, with the pain localized to the site of their original rash. This long-lasting pain compares with the severity of long-standing rheumatics and osteo-arthritis and is accompanied by severe allodynia causing significant suffering, and a financial burden that is manifested in both healthcare costs and loss of quality-adjusted life years. Prevention of PHN may be achieved with the Zoster vaccine, although there is still a large segment of unvaccinated population. Moreover, the Zoster vaccine is not always effective for prevention. Current treatment includes medical (systemic tricyclic antidepressants, anticonvulsants and opioids, topical lidocaine and capsaicin) and interventional (subcutaneous Botox injections, nerve blocks and nerve stimulation) therapies. These therapies are not always effective, and each carries their own profile of side effects and risks. Moreover, up to 50% of patients with PHN are refractory to management. Recent evidence is emerging to support the use of topical local anesthetics for the treatment of PHN. Two small studies recently found topical lidocaine spray to be effective in treating paroxysmal pain attacks associated with PHN. Bupivacaine is a longer-lasting local anesthetic, and a film-forming formulation allows easy and durable application to the affected skin. Recent studies show that topical film-forming bupivacaine is safe and as effective as lidocaine for the treatment of PHN. Summary PHN is an important though common complication of HZ and can cause long-lasting pain and disability. Current treatment for PNH is limited by efficacy and safety profiles of individual therapies. Recent evidence points to topical local anesthetics as an effective and safe alternative to conventional therapy. Film-forming bupivacaine may offer a durable and safe option for this otherwise difficult to treat syndrome.

Inhibiting BDNF/TrkB.T1 receptor improves resiniferatoxin-induced postherpetic neuralgia through decreasing ASIC3 signaling in dorsal root ganglia

“…Current treatments for PHN include medical (systemic tricyclic antidepressants, topical lidocaine and capsaicin, anticonvulsants and opioids) and interventional therapies (subcutaneous botulinum toxin injections, nerve blocks and neurostimulation )[ 3 ]. However, there is still a lack of effective clinical therapy and up to 50% of patients with PHN are refractory to management [ 4 ]. Thus, it is meaningful to develop novel efficacious therapeutic strategies for preventing PHN.…”

Ultrasound-Guided Continuous Thoracic Paravertebral Infusion of Methylene Blue in the Treatment of Postherpetic Neuralgia: A Prospective, Randomized, Controlled Study

“…Postherpetic neuralgia (PHN) is the most frequent chronic complication of herpes zoster (HZ), and is manifested by neuropathic pain after the rash has healed [1]. Recent studies have shown that the annual incidence of HZ is approximately 3.4 cases per 1000 persons, and it rises sharply from the age of 50 years to approximately 10.9 cases per 1000 person in the C 80 age group [2,3]. It is estimated that approximately 20% of HZ patients develop PHN [4].…”

Thermographic follow-up of postherpetic neuralgia (PHN) subsequent to Ramsay Hunt syndrome with multicranial nerve (V, VII, VIII and IX) involvement: a case report

“…Lidocaine is a local anaesthetic that modulates pain by blocking the transmission of impulses in peripheral nerves through the blockade of voltage-gated sodium channels [ 14 ]. Topical anaesthetics can also suppress the phosphorylation of extracellular signal-regulated kinases (ERKs) in the dorsal horn of the spinal column, which plays a critical role in signal transduction of the pain pathway [ 15 , 16 ]. The use of topical anaesthetics could relieve the pain of neuropathic pain or pain of PHN through a combination of central and peripheral nervous system actions [ 17 ].…”