Side Effects-Second Generation
Lack of sedative or antimuscarinic effects.
Several agents were found, after marketing, to cause a potentially fatal arrhythmia (a ventricular tachycardia referred to as torsades de pointes), because of block of certain potassium channels in the heart. The risk, which was rare, increased when these agents were taken with drugs that inhibited their biotransformation by CYP 3A4 (such as erythromycin). One of these, terfenadine (SELDANE) was withdrawn from the market and replaced by its metabolite, fexofenadine, which is not cardiotoxic.