In a crossover bioavailability study, a single 100 mg oral dose of a tablet produces an AUC of 500 mg·h/L, while the same dose given intravenously produces an AUC of 1000 mg·h/L. What is the absolute oral bioavailability of the tablet?
- A 25%
- B 50% ✓
- C 75%
- D 200%
Correct answer: B. 50%
Explanation
Absolute bioavailability is calculated as F equals (AUC oral divided by AUC intravenous) when doses are identical, since AUC is proportional to the fraction of dose reaching systemic circulation. Here 500 divided by 1000 gives 0.5, or 50%, meaning half the administered dose escapes gut and hepatic first-pass loss. Option D results from inverting the ratio, a common error, and option A has no arithmetic basis for these values.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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