Pharmacokinetics: bioavailability from AUC: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Pharmacokinetics: bioavailability from AUC

Sample item

In a study, 50 mg of a drug is given intravenously and gives an AUC of 40 mg.h/L. A 100 mg oral dose of the same drug gives an AUC of 40 mg.h/L. What is its oral bioavailability?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. 50%

Bioavailability F = (AUC oral / dose oral) / (AUC IV / dose IV). Here (40/100) / (40/50) = 0.4 / 0.8 = 0.5, or 50%. The AUCs must be corrected for the different doses.

Option by option

  • A. 200%

    This inverts the dose correction and gives an impossible bioavailability above 100%.

  • B. 50% (correct)

    Correct. 0.4 divided by 0.8 equals 0.5, so 50% reaches the circulation.

  • C. 100%

    Equal AUCs give 100% only when the doses are identical, which is not so here.

  • D. 25%

    This applies the dose correction twice and is not what the data give.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, 50%. Bioavailability F = (AUC oral / dose oral) / (AUC IV / dose IV).

Why is "200%" not the answer?

This inverts the dose correction and gives an impossible bioavailability above 100%.

Why is "100%" not the answer?

Equal AUCs give 100% only when the doses are identical, which is not so here.

Why is "25%" not the answer?

This applies the dose correction twice and is not what the data give.

What concept does this question test?

It tests Pharmacokinetics: bioavailability from AUC in Pharmacology. Here (40/100) / (40/50) = 0.4 / 0.8 = 0.5, or 50%. The AUCs must be corrected for the different doses.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Pharmacokinetics: bioavailability from AUC?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.