This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
[{'content': '100% bioavailability is seen with which route \nSelect and explain. \nA. Oral, B. Intravenous, C. Rectal, D. Subcutaneous', 'role': 'user'}, {'content': "Answer: B \nExplanation: (Ref: Katzung Pharmacology, 10th ed. Ch 3)Bioavailability is defined as the fraction of unchanged drug reaching the systemic circulation following administration by any route.In case a drug is given orally, the bioavailability shall be less than 100%. This is due to#Incomplete extent of absorption#First pass metabolismRoutes of administration, bioavailability, and general characteristicsRoute of AdministrationGeneralcharacteristicsBioavailabilityIntravenousOnset of action is fastest100%IntramuscularPainful75-100%SubcutaneousLesser volumes can be given compared to intramuscular route75-100%Per oralMost convenient from patients' perspective MC used route5% to <100%First pass metabolism limits blood levelsPer rectalLess first pass metabolism than peroral30 to <100%TransdermalVery slow absorption.Lack of first pass effectProlonged duration of action80-100%", 'role': 'assistant'}]