This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
[{'content': 'Which of the following is an active metabolite of another drug and is available as a separate drug for the treatment of angine? \nSelect and explain. \nA. Isosorbide mononitrate, B. Isosorbide dinitrate, C. Nitroglycerine, D. Propanolol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Ref: KDT 6/e p525) It is a metabolite of isosorbide dinitrate and is also available as a separate drug. It undergoes least first pass metabolism.', 'role': 'assistant'}]