Method for treating nerve injury pain associated with shingles

Abstract

Methods and compositions are offered for reducing nerve injury pain associated with shingles (herpes-zoster and post-herpetic neuralgia), where intradermal delivery of lidocaine is maintained for a predetermined period of time. The lidocaine appears to specifically affect the damaged nerve fibers, while leaving the undamaged and normal nerve fibers with retention of response to other stimuli. Lidocaine formulations are provided which allow for the necessary dosage of the lidocaine in the dermis during the period of treatment. The formulation may be covered with an occlusive or non-occlusive dressing, which protects the lidocaine formulation from mechanical removal and enhances the transport of the lidocaine into the dermis. Long term relief is realized after maintenance of the administration of lidocaine has been terminated.

Description

INTRODUCTIONTechnical FieldThe field of this invention is extended pain relief methods and compositions.BACKGROUND OF THE INVENTIONThe mechanism of pain generation in post-herpetic neuralgia is unknown. Post-herpetic neuralgia (PHN) begins with a cutaneous rash and the chronic state is notable for skin scarring and painfully sensitive skin (allodynia). Although the initial outbreak may be widespread, occasionally appearing to cover more than the area of skin innervated by a single dorsal root ganglion, most PHN patients are able to localize a limited area of skin as the source of their pain. PHN patients nearly always have a sensory deficit in the region obtained.The majority of work carried out on topical agents for analgesia in recent years has been in patients with PHN. Other conditions, particularly diabetic neuropathy, have been treated in clinical trials and clinical practice with topical agents, primarily capsaicin. Topical therapies represent a very attractive alternative to...

AI Technical Summary

Problems solved by technology

The primarily elderly patients with PHN frequently cannot be treated with tricyclic antidepressants because of pre-existing cognitive impairment, cardiac disease, or systemic illness.

Side effects like constipation, dry mouth and sedation may prove so bothersome that compliance becomes a major problem in therapy.

Non-narcotic analgesics are rarely effective and benzodiazepines have been proven ineffective.

Opioids may be effective, but have not been adequately evaluated as long term treatment for PHN or diabetic neuropathy.

Once PHN is well established, local anesthetic peripheral nerve, epidural, or synthetic blocks are unlikely to provide more than temporary relief.

For such a chronic condition, it is difficult to justify highly invasive procedures, with substantial risks, just to gain hours, or at best days, of relief.