Which of the following drugs when combined with erythromycin may cause ventricular arrhythmias?: (A) Tetracycline, (B) Streptomycin, (C) Ebastine, (D) Cisapride
Answer is D. As Erythromycin is enzyme inhibitor of CYP3A4 --> concentration of drugs like cisapride, Terfenadine and Astemizole increases--> blocking the K+ channel --> QT prolongation --> ventricular arrhythmias.