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 process by which the amount of a drug in the body decreases after administration, but before entering the systemic circulation is called: 
Select and explain. 
A. Excretion, B. First pass effect, C. First order elimination, D. Metabolism
B: First pass effect
Answer: B: First pass effect 
Explanation: Reduction in the amount of drug before it enters the systemic circulation is called first pass metabolism (also known as first pass effect) whereas, if the amount of drug decreases after entry into the systemic circulation, it is called elimination. Latter includes excretion and metabolism.