This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
[{'content': 'Two antihistaminics terfenadine and astemizole were withdrawn from the market following the occurrence of cardiac arrhythmias when they were present in high levels in the blood. These effects were explained by the fact: \nSelect and explain. \nA. Use of these drugs by addicts, B. Genetic predisposition to metabolize succinylcholine slowly, C. Concurrent treatment with phenobarbital, D. Treatment of these patients with erythromycin, a macrolide antibiotic', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Astemizole and terfenadine are metabolized by microsomal enzymes. Erythromycin inhibits these enzymes and raises the plasma concentration of these drugs. At high levels, these agents block cardiac K+ channels leading to arrhythmias.', 'role': 'assistant'}]