In a bioequivalence study, a tablet formulation of a new drug yields an AUC of 250 mg.h/L after a single oral dose. An intravenous dose of the same amount of the same drug yields an AUC of 500 mg.h/L. What is the absolute bioavailability of the oral formulation?
- A 100 percent
- B 75 percent
- C 50 percent ✓
- D 25 percent
Correct answer: C. 50 percent
Explanation
Absolute bioavailability equals the dose-corrected ratio of the oral AUC to the intravenous AUC, since intravenous administration represents complete systemic delivery. Here 250 divided by 500 equals 0.5, so 50 percent of the oral dose reaches the circulation unchanged. Losses may arise from incomplete dissolution, gut wall metabolism, or hepatic first-pass extraction. Comparing against an intravenous reference is essential because relative bioavailability between two oral products says nothing about absolute systemic exposure.
Reference: Katzung Basic and Clinical Pharmacology, 15th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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