Second-generation antihistamines astemizole and terfenadine were removed from the market because they produced::

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Two second-generation antihistamines, astemazole and terfenadine, were removed from the market because they produced serious cardiovascular and hepatic effects that were fatal in some patients. These drugs delayed conduction within the heart and prolonged the QTc interval. On the ECG, prolongation of the QTc interval reflects a change in cardiac conduction that makes it possible for life-threatening ventricular arrhythmias to occur. The mechanism is a direct interaction with selective ion channels (K⁺, Na⁺, Ca⁺⁺) in the myocardium that interrupts normal cardiorhythm.

Second-Generation Antihistamines Astemizole and Terfenadine Were Removed from the Market