Bioavailability is defined as: (A) The volume of plasma completely cleared of a specific compound per unit time and measured as a test of kidney function, (B) The percentage of drug that is detected in the systemic circulation after its administration, (C) Both, (D) None
Answer is B. Bioavailability refers to the rate and extent of absorption of a drug from a dosage form as determined by its concentration-time curve in blood or by its excretion in urine It is a measure of the fraction (F ) of an administered dose of a drug that reaches the systemic circulation in the unchanged form. Bioavailability of drug injected i.v. is 100%, but is frequently lower after oral ingestion BA=F=Area under curve oral/ AUC IV Ref-KD Tripathi Pharmacology 7th edition (page no;32)