02/16/11

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FROM THE ANNUAL MEETING OF THE AMERICAN ACADEMY OF DERMATOLOGY

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Vitals

Major Finding: Of 133 consecutive patients who started the dual therapy within 72 hours after developing their first vesicle, only 9.8% had postherpetic neuralgia as defined by any zoster pain 6 months after rash onset.

Data Source: An open-label study of 133 consecutive patients with acute herpes zoster.

Disclosures: The study was funded by the Foundation for Advances in Therapeutics and Prevention. The valacyclovir was provided by GlaxoSmithKline. Dr. Lapolla disclosed serving as a subinvestigator for NeurogesX and Inhibitex.

NEW ORLEANS - Gabapentin given in combination with valacyclovir in patients with acute herpes zoster reduces the incidence of postherpetic neuralgia, based on the results of an open-label study.

Of 133 consecutive patients who started the dual therapy within 72 hours after developing their first vesicle, only 9.8% had postherpetic neuralgia (PHN), as defined by any zoster pain 6 months after rash onset, Dr. Whitney Lapolla reported at the annual meeting of the American Academy of Dermatology.

Dr. Whitney Lapolla

This was a study without a placebo arm, so it's necessary to turn to the published literature for historical controls. A recent review of eight clinical trials of antiviral therapy for herpes zoster showed a PHN rate of 11%-33% at 6 months, with an average of about 19%, convincingly higher than with gabapentin plus valacyclovir, said Dr. Lapolla of the center for clinical studies at the University of Texas at Houston.

"Why is this important? Postherpetic neuralgia is a devastating illness causing extremely poor quality of life, and it’s difficult to treat once established," she said. "The available treatments include tricyclic antidepressants, the anticonvulsants gabapentin and pregabalin, and systemic and topical analgesics. Unfortunately, if you add all these up, the result is very poor symptom control, so the goal needs to be to prevent postherpetic neuralgia from developing in the first place."

The prevention of PHN takes on added importance in light of several recent reports suggesting the incidence of PHN may be increasing. Proposed explanations for the upward trend include the aging of the baby boomers, increased use of immunosuppressive therapies, and varicella vaccination in childhood, Dr. Lapolla continued.

Of course, the herpes zoster vaccine has been shown to reduce the incidence of zoster by 51% and, more importantly, reduce the risk of PHN by 67%, but patients have been slow to adopt this vaccine.

Dr. Lapolla said one of the key implications of her prevention study is that it’s particularly important to offer the gabapentin-valacyclovir regimen to patients at highest risk for PHN, namely those over age 70 and/or with severe acute zoster pain, as defined by a pain score of 7 or more on a 10-point Likert pain scale at presentation.

Of the 133 participants in the study, 40 were aged 70 or older, 47 were aged 50-59 years, and 46 were aged 60-69. Two-thirds were women. Sixty-two percent had severe zoster pain at presentation, and the rest had moderate pain, as defined by a score of 4-6 on the 10-point scale.

At follow-up evaluations conducted at 3, 4, and 6 months, a higher proportion of the 70-plus age group had pain compared with younger patients. Among the 70-plus population, a pain score greater than 0 was present in 22.5% at 3 months, 25% at 4 months, and 17.5% at 6 months. Among 50- to 59-year-olds, the rates at the same time points were 12.8%, 12.8%, and 4.3%. Pain rates were intermediate in the 60-69 age group.

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