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
Glyceryl trinitrate is given by a sublingual route because of: 
Select and explain. 
A. High hepatic first-pass metabolism., B. High bioavailability., C. Short t- half in plasma., D. Extensive protein binding.
A: High hepatic first-pass metabolism.
Answer: A: High hepatic first-pass metabolism. 
Explanation: In the sublingual route, the liver is bypassed and drugs with the high first-pass metabolism are absorbed directly into systemic circulation.