This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
Causes of reduced bioavailability of a drug includes 
Select and explain. 
A. High first pass metabolism, B. Increased absorption, C. IV drug administration, D. High lipid solubility
A: High first pass metabolism
Answer: A: High first pass metabolism 
Explanation: When the metabolism of a drug is high during its passage from the site of absorption into the systemic circulation, the rate, and extent of absorption of that drug decreases. absorption- amount of drug reaching the systemic circulation from the site of administration (Ref.Essentials of medical pharmacology TD Tripathi 7th edition page no.16,27)