Which of the following is not an antibiotic?

Appeared in: KPSC Staff Nurse - 2018

Explanation

Ranitidine is an H2-receptor antagonist, not an antibiotic.
Its mechanism of action involves blocking histamine H2 receptors on the parietal cells of the stomach.
This action decreases gastric acid production, which helps in treating acid-related disorders.
It does not have any activity against bacteria and is therefore not used for treating infections.

Option A: Tetracycline is a well-known broad-spectrum antibiotic.
Option C: Ofloxacin is a fluoroquinolone antibiotic.
Option D: Penicillin is one of the most famous and widely used classes of antibiotics (beta-lactams).

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Drug Classification and Mechanism of Action as background academic context rather than a clinical decision trigger.
A core nursing responsibility is understanding drug classifications to ensure safe medication administration. Confusing an H2 blocker with an antibiotic could lead to an untreated infection and potential harm.
This knowledge is crucial for antibiotic stewardship, which aims to prevent antibiotic resistance by ensuring antibiotics are used only when necessary for bacterial infections.
What if? If a patient had a stomach ulcer caused by the bacterium Helicobacter pylori, the treatment regimen would actually include both antibiotics (like clarithromycin and amoxicillin) and a drug to reduce stomach acid (like a proton pump inhibitor, which is similar in goal to an H2 blocker). This highlights how different drug classes are combined to treat complex conditions.

How to Approach the Question

First, carefully read the question and note the negative keyword 'not'. This means you are looking for the option that does not belong to the specified category.
The category is 'antibiotic'. Your task is to identify the drug that is not used to treat bacterial infections.
Evaluate each option based on its drug class and primary use.
Tetracycline is an antibiotic.
Ranitidine is an H2 blocker for acid reflux.
Ofloxacin is an antibiotic.

Concept Tested & Keywords

Concept Tested: Drug Classification and Mechanism of Action
Stem keywords: antibiotic
Lead-in keywords: not
Negative lead-in flag: The question asks to identify the option that is NOT an antibiotic.

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 1692-1694, 1686-1688

E6 Pharmacology Katzung 16e p. 1279-1281

Practise the full KPSC Staff Nurse - 2018

Attempt every question from this paper in a timed mock, then review the full solution for each one.