Which of the following drugs is an example of Vitamin K antagonists?

Appeared in: Bihar NHM CHO-2025

Explanation

Warfarin is a coumarin derivative that acts as an oral anticoagulant.
Its primary mechanism is the inhibition of the enzyme Vitamin K epoxide reductase (VKOR) in the liver.
This inhibition prevents the synthesis of functional Vitamin K-dependent clotting factors: II (prothrombin), VII, IX, and X.
By depleting these factors, Warfarin reduces the blood's ability to clot, making it effective for preventing and treating thromboembolic disorders.

Option A: Baclofen is a muscle relaxant and antispasmodic agent, not an anticoagulant. It acts on the central nervous system to relieve muscle spasms.
Option C: Metronidazole is an antibiotic and antiprotozoal medication. It is used to treat infections, not to alter blood coagulation.
Option D: Acetazolamide is a carbonic anhydrase inhibitor. Its primary effects are diuretic (increasing urine output) and reducing intraocular pressure.

Visual 1: Diagram - The coagulation cascade, highlighting the Vitamin K-dependent factors (II, VII, IX, X) and showing where Warfarin intervenes to block the cycle.
Visual 2: Chart - A list of common foods high in Vitamin K (e.g., spinach, kale, broccoli) to illustrate the concept of dietary consistency for patients on Warfarin.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Anticoagulants and Vitamin K Antagonists as background academic context rather than a clinical decision trigger.
Monitoring the International Normalized Ratio (INR) is critical for patient safety. Nurses must ensure regular blood tests are done and doses are adjusted based on a therapeutic range (typically 2.0-3.0).
Patient education is a key nursing responsibility. This includes teaching about the importance of consistent Vitamin K intake, recognizing signs of bleeding, and avoiding medications (like aspirin or NSAIDs) that can increase bleeding risk without consulting a doctor.
What if? If a patient on Warfarin has an INR of 5.0 and shows signs of active bleeding, the nurse's priority is to stop the Warfarin, notify the physician immediately, and prepare to administer the antidote, Vitamin K, and potentially fresh frozen plasma (FFP) as ordered.

How to Approach the Question

First, identify the core concept in the question stem, which is 'Vitamin K antagonists'.
This is a pharmacology recall question. Access your knowledge of major drug classes.
Evaluate each option based on its primary mechanism of action and drug classification.
Option A, Baclofen, is a muscle relaxant. Eliminate it.
Option B, Warfarin, is a classic oral anticoagulant known to interfere with Vitamin K. This is a strong candidate.
Option C, Metronidazole, is an antibiotic. Eliminate it.

Concept Tested & Keywords

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Practise the full Bihar NHM CHO-2025

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