General pharmacology and pharmacokinetics: maintenance dose calculation: 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 · General pharmacology and pharmacokinetics: maintenance dose calculation

Sample item

An oral drug has a clearance of 5 L per hour and an oral bioavailability of 0.5. The target average steady-state plasma concentration is 10 mg per L. Which regimen gives this target?

A600 mg every 12 hoursB2400 mg every 12 hoursC300 mg every 12 hoursD1200 mg every 12 hours

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

The answer and the reasoning

D. 1200 mg every 12 hours

Dosing rate equals clearance times target concentration divided by bioavailability, which is 5 x 10 / 0.5 = 100 mg per hour. Over 12 hours this is 1200 mg. Forgetting bioavailability halves the answer.

Option by option

A. 600 mg every 12 hours
This ignores bioavailability and would give only half the needed exposure.
B. 2400 mg every 12 hours
This gives a 24-hour amount in a 12-hour schedule and would double the target level.
C. 300 mg every 12 hours
This multiplies by bioavailability instead of dividing, which underdoses four-fold.
D. 1200 mg every 12 hours (correct)
Correct. 100 mg per hour for 12 hours is 1200 mg.

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.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is D, 1200 mg every 12 hours. Dosing rate equals clearance times target concentration divided by bioavailability, which is 5 x 10 / 0.

Why is "600 mg every 12 hours" not the answer?

This ignores bioavailability and would give only half the needed exposure.

Why is "2400 mg every 12 hours" not the answer?

This gives a 24-hour amount in a 12-hour schedule and would double the target level.

Why is "300 mg every 12 hours" not the answer?

This multiplies by bioavailability instead of dividing, which underdoses four-fold.

What concept does this question test?

It tests General pharmacology and pharmacokinetics: maintenance dose calculation in Pharmacology. 5 = 100 mg per hour. Over 12 hours this is 1200 mg. Forgetting bioavailability halves the answer.

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 General pharmacology and pharmacokinetics: maintenance dose calculation?

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.