serious arrhythmia induced by terfenadine-erythromycin interactions

since the introduction of our local manufacturing of terfenadine, we have observed and expressed our concern about a small but increasing number of serious ventricular arrhythmias associated with the use of this non sedating antihistamine. in january 1997 a case of torsade de pointes ventricular tachycardia was detected in a previously healthy woman taking terfenadine with erythromycin. electrocardiography revealed qt interval prolongation and qrs widening. one hour after emergency room admission, her arrhythmia degenerated to ventricular fibrillation and she died of cardiac arrest. episodes of torsade de pointes are most likely the result of the quinidine-like action of terfenadine. dosage restriction and awareness of the clinical conditions and drug interactions capable of inhibiting the metabolism of terfenadine are essential for prevention of this serious reaction.