Which is the specific antagonist that neutralises heparin-induced anticoagulation?

Appeared in: Bihar NHM CHO-2025

Explanation

Protamine sulfate is the specific antidote for reversing heparin-induced anticoagulation.
Protamine is a strongly basic (cationic) peptide that binds with the strongly acidic (anionic) heparin.
This binding forms a stable, inactive salt complex, which immediately neutralizes heparin's anticoagulant effect.
The neutralization reaction is rapid, with effects seen within minutes of intravenous administration.

Option B: Streptokinase is a thrombolytic agent, or 'clot buster', used to dissolve existing clots.
Option C: Alteplase is a tissue plasminogen activator (tPA), another type of thrombolytic drug that breaks down clots.
Option D: Metoclopramide is an antiemetic and prokinetic agent used for gastrointestinal issues like nausea, vomiting, and gastroparesis.

Visual 1: Diagram - A diagram illustrating the ionic bonding between the positively charged protamine molecule and the negatively charged heparin molecule, resulting in a neutral, inactive complex. This helps visualize the mechanism of action.
Visual 2: Table - A quick-reference chart of common emergency drugs and their specific antidotes, including Heparin-Protamine, Warfarin-Vitamin K, Opioids-Naloxone, and Benzodiazepines-Flumazenil.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Antidote for Heparin as background academic context rather than a clinical decision trigger.
Nurses must know the specific antidote for heparin to rapidly manage life-threatening bleeding, a major complication of heparin therapy.
The dose of protamine is critical and is calculated based on the amount of heparin remaining in the body. The standard guideline is 1 mg of protamine for every 100 units of heparin.
Protamine must be administered slowly via IV infusion (not exceeding 50 mg over 10 minutes) as rapid injection can cause severe hypotension, flushing, and bradycardia.

How to Approach the Question

This is a factual recall question from pharmacology, a common type in nursing exams.
First, identify the key drug mentioned in the question stem: 'heparin'.
Next, understand what the question is asking for: the 'specific antagonist' that 'neutralises' its effect.
Mentally categorize heparin as an anticoagulant.
Scan the options to find the drug known to be the antidote for heparin.
Eliminate the other options by identifying their drug class and primary use: Streptokinase and Alteplase are thrombolytics (clot-busters), and Metoclopramide is an antiemetic.

Concept Tested & Keywords

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KD Tripathi - Essentials of Medical Pharmacology (6th Edition) p. 21-546

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.