This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
The nitrate which does not undergo first pass metabolism is 
Select and explain. 
A. Isosorbide mononitrate, B. Nitroglycerin, C. Pentaerythratol tetranitrate, D. Isosorbide dinatrate
A: Isosorbide mononitrate
Answer: A: Isosorbide mononitrate 
Explanation: Isosorbide mononitrate, is a medication used for hea related chest pain (angina), hea failure, and esophageal spasms. It can be used both to treat and to prevent hea related chest pain, however is generally less preferred than beta blockers or calcium channel blockers. It is taken by mouth Isosorbide mononitrate is a nitrate-class drug used for the prevention of angina pectoris. Refer kDT 6/e p 525