Antibiotics: aminoglycoside dosing: 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 · Antibiotics: aminoglycoside dosing

Sample item

A hospital pharmacist advises giving gentamicin as a single daily dose rather than three divided doses for a Gram-negative infection. What is the main pharmacological rationale?

APoor tissue penetration requiring maximal trough levelsBTime-dependent killing with a short half-lifeCConcentration-dependent killing with a post-antibiotic effect, and less renal uptakeDNeed to avoid first-dose hypersensitivity

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

The answer and the reasoning

C. Concentration-dependent killing with a post-antibiotic effect, and less renal uptake

Aminoglycoside killing rises with peak concentration, and bacteria remain suppressed after levels fall (post-antibiotic effect). Renal cortical uptake is saturable, so high peaks with a long drug-free interval reduce nephrotoxicity. Peak and trough levels are monitored accordingly.

Option by option

A. Poor tissue penetration requiring maximal trough levels
Higher troughs increase toxicity and are avoided, not sought.
B. Time-dependent killing with a short half-life
Aminoglycosides show concentration-dependent, not time-dependent, killing.
C. Concentration-dependent killing with a post-antibiotic effect, and less renal uptake (correct)
Correct. High peaks maximise killing, while the trough-free interval limits renal toxicity.
D. Need to avoid first-dose hypersensitivity
The regimen has no relation to preventing hypersensitivity.

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 C, Concentration-dependent killing with a post-antibiotic effect, and less renal uptake. Aminoglycoside killing rises with peak concentration, and bacteria remain suppressed after levels fall (post-antibiotic effect).

Why is "Poor tissue penetration requiring maximal trough levels" not the answer?

Higher troughs increase toxicity and are avoided, not sought.

Why is "Time-dependent killing with a short half-life" not the answer?

Aminoglycosides show concentration-dependent, not time-dependent, killing.

Why is "Need to avoid first-dose hypersensitivity" not the answer?

The regimen has no relation to preventing hypersensitivity.

What concept does this question test?

It tests Antibiotics: aminoglycoside dosing in Pharmacology. Renal cortical uptake is saturable, so high peaks with a long drug-free interval reduce nephrotoxicity. Peak and trough levels are monitored accordingly.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Antibiotics: aminoglycoside dosing?

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.