This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
[{'content': 'GTN is given sub-lingually, why? \nSelect and explain. \nA. To avoid first pass metabolism, B. Rapid effect, C. Gastric irritation, D. To avoid side effects', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a (To avoid first pass metabolism) Ref: Goodman & Gilman, 11th ed, p. 3SUBLINGUAL ADMINISTRATIONVenous drainage from the mouth is to the superior vena cava, which protects highly soluble drugs like nitroglycerin from rapid hepatic first-pass metabolism. If a tablet of nitroglycerin were swallowed, the accompanying hepatic metabolism would be sufficient to prevent the appearance of any active nitroglycerin in the systemic circulation.', 'role': 'assistant'}]