100 % bioavailability is seen with which route: (A) Oral, (B) Intravenous, (C) Rectal, (D) Subcutaneous
Answer is B. • 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
■ The incomplete extent of absorption
■ First pass metabolism
Routes of Administration, Bioavailability, and General Characteristics