Torsade De Pointes Caused By Concomitant Use Of Ketoconazole And Terfenadine

摘要

A 47-year-old female developed frequent syncope eight days after the administration of oral ketoconazole and terfenadine for fungal infection and urticaria respectively. ECG at hospital admission showed prolonged QT interval and TDP. The patient had no previous history of syncope nor did she have other risk factors for TDP. Both ketoconazole and terfenadine were immediately discontinued, followed by intravenous infusion of isoprenaline (2.0 μg/min) to maintain the heart rate at 100 beats/min. TDP resolved after the management. QT interval returned to normal range within 5 days of admission. She had no recurrence in TDP or QT prolongation during the follow up of six months. Conclusions: Terfenadine prolongs QT interval and leads to life-threatening ventricular arrhythmia. This cardiac toxicity may be enhanced by concomitant use of liver enzyme inhibitor ketoconazole.