Nontraditional analgesics for the management of postherpetic neuralgia.
The pathogenesis and clinical manifestations of herpes zoster and postherpetic neuralgia and the use of nontraditional analgesics in the management of postherpetic neuralgia are reviewed. Herpes zoster represents the reactivation in an immunocompromised host of dormant varicella-zoster virus (Herpesvirus varicellae) contracted during a previous episode of chickenpox. Fever, neuralgia, and paresthesia occur four to five days before skin lesions develop. Acute herpes zoster pain usually does not last more than two weeks after all skin lesions have healed. Postherpetic neuralgia is defined as pain that persists in the affected dermatomes after the disappearance of all skin crusts. The neuralgia can vary from "lightninglike" stabbing pain to constant, burning pain with hyperesthesia; it can persist for years and is often refractory to traditional analgesic therapy. A number of nontraditional analgesic agents have been used in the management of postherpetic neuralgia. Tricyclic antidepressants, especially amitriptyline, have been used alone and in combination with phenothiazines or anticonvulsants (carbamazepine, phenytoin, valproate sodium), with good results. The effectiveness of phenothiazines or anticonvulsants as sole therapeutic agents has not been demonstrated. Although the intralesional administration of corticosteroids appears to be beneficial, considerable fear about the potential for these agents to precipitate widespread viral dissemination exists. Positive results have been reported with levodopa, amantadine, and interferon, but the role of these agents in the prevention of postherpetic neuralgia remains unclear. Nontraditional analgesic agents are useful in the management of postherpetic neuralgia, but patients must be selected and monitored appropriately. A tricyclic antidepressant (especially amitriptyline) is a reasonable first choice.