A patient taking ketoconazole and terfenadine both, is prone to -: (A) Cardiac arrythmia, (B) Toxicity of ketoconazole, (C) Congestive cardiac failure, (D) All of the above
Answer is A. Ans. is 'a' i.e., Cardiac arrhythmia o Terfenadine causes blockade of delayed rectifier K+ channels in the hea at higher concentration and can cause Torsades De Pointes (Polvmorph ventricular tachcardia) --> Prolonged QT interval. Drugs inhibiting the metabolism of terfenadine by inhibiting CYP3AY enzyme, can precipitate ventricular arrythmia Erythromycin, clarithromycin, itraconazole, ketoconazole.