This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
The Nitrate which does not undergo first pass metabolism is - 
Select and explain. 
A. Isosorbide mononitrate, B. Nitroglycerine, C. Pentaerythritol tetranitrate, D. Isosorbide dinitrate
A: Isosorbide mononitrate
Answer: A: Isosorbide mononitrate 
Explanation: Ans. is 'a' i.e., Isosorbide mononitrate o "All nitrates except isosorbide mononitrate undergo extensive but variable first pass metabolism in liver".