Combined use of astemizole and ketoconazole resulting in torsade de pointes.

Torsade de pointes is a serious ventricular arrhythmia which is usually associated with a long QT interval. It is important to recognize the possible predisposing factors for the management of this arrhythmia. Prolongation of the QT interval and torsade de pointes has been reported in patients with an overdose of astemizole. We report on a 63-year-old woman presenting with torsade de pointes and a long QT interval caused by the combined use of astemizole (at recommended dosage), and ketoconazole. After discontinuation of these drugs and treatment with a temporary pacemaker, magnesium sulfate and lidocaine, the arrhythmia was no longer observed and she was discharged in good condition with a normal electrocardiogram. This case should alert clinicians to the possibility of torsade de pointes with the combined use of astemizole and ketoconazole.