This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'A 69-year-old man with heart failure and paroxysmal atrial fibrillation is prescribed amiodarone for maintenance of sinus rhythm. Which of the following is a known characteristic of amiodarone? \nSelect and explain. \nA. excellent oral absorption, B. a short half-life, C. an active metabolite, D. few drug interactions', 'role': 'user'}, {'content': 'Answer: C \nExplanation: With prolonged treatment, the active N-desethyl derivative of amiodarone accumulates in plasma, and its concentration may exceed that of the parent compound. Amiodarone is poorly (approximately 30%) absorbed and there is marked interindividual variability. The half-life is long, 25-60 days, presumably because it is extensively bound to tissues, resulting in a large volume of distribution and a reservoir of drug. Complicating the use of amiodarone is multiple drug interactions and toxicities including liver, thyroid, and lung.', 'role': 'assistant'}]