Pharmacology This antihistaminic drug can cause cardiac arrhythmia at a high dose by blocking cardiac K+ channels. It is most likely to be : A Levocetirizine B Fexofenadine C Astemizole D Loratadine 💡 Explanation This antihistaminic drug can cause cardiac arrhythmia at a high dose by blocking cardiac K+ channels. It is most likely to be : ✓ Correct Answer: C. Astemizole