Few Studies on Pharmacotherapies for Postherpetic Neuralgia Report Adverse Events

In studies reporting on pharmacologic treatments for postherpetic neuralgia, few report the incidence of adverse events (AEs) or withdrawal rates caused by AEs, according to a systematic review to be presented at the 17th World Congress on Pain in Boston, Massachusetts.

The researchers performed a systematic review to identify AEs as well as AE-associated withdrawal rates of 18 pharmacotherapies for the treatment of postherpetic neuralgia. Treatments examined were amitriptyline, divalproex sodium, fluoxetine, gabapentin, fluphenazine, pregabalin, levetiracetam, nortriptyline, desipramine, maprotiline, lorazepam, intravenous lidocaine, tramadol, oxycodone, methadone, morphine, topical lidocaine, and topical capsaicin. The Cochrane Library was used to identify randomized controlled double-blind trials that enrolled patients with postherpetic neuralgia.

Studies included in the review examined the effects of a single dose up to those of a 16-week treatment for postherpetic neuralgia. Serious AEs, including increased blood pressure and elevated liver enzyme levels, were reported in a low percentage of patients across studies (0.0%-8.8%). Withdrawal rates caused by AEs ranged from 0.0% to 31.5%.

“Details of adverse events and withdrawal rates are not always reported in studies investigating the pharmacological management of postherpetic neuralgia,” the investigators wrote. “This data is needed to inform clinical decision-making for the prescription of medication for postherpetic neuralgia. Future research on postherpetic neuralgia should include drugs recommended as first-line by the Special Interest Group on Neuropathic Pain (eg, duloxetine and venlafaxine).”

Reference

Shimizu T, Doody C, Blake C, Fullen B. Adverse events associated with pharmacological therapies for post-herpetic neuralgia: an overview of Cochrane reviews. Presented at: World Congress on Pain 2018; September 12-16, 2018; Boston, MA. Poster 63856.

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