Propoxyphene-induced torsades de pointes

Abstract

t The U.S. Food and Drug Administration (FDA) recently recommended that propoxyphene (an opioid analgesic drug used for the relief of moderate pain) be withdrawn from the U.S. market. This FDA recommendation followed concerns of possible propoxyphene-induced cardiac side effects, including prolongation of the QT interval. The decision was based on experimental studies showing that propoxyphene blocks HERG channels as well as on a single “thorough QT study” showing an averaged 30-ms increment of QTc in healthy volunteers taking propoxyphene. Howver, propoxyphene has never been shown to trigger torsades e pointes and is not listed as a potentially torsadogenic drug in the most frequently quoted website on drug-induced QT prolongation. We present a case of propoxyphene-induced orsade in a patient with several risk factors for drug-induced ong QT syndrome.