What is the antidote of heparin?

Appeared in: PGIMER Sangrur NO - 2023

Explanation

Protamine sulphate is the specific and rapid-acting antidote for heparin overdose.
It functions as a chemical antagonist. Being a strongly basic protein, it binds to the strongly acidic heparin, forming a stable and inactive salt complex.
This neutralization reaction effectively and immediately reverses heparin's anticoagulant effects.
The standard neutralizing dose is 1 mg of protamine for every 100 units of heparin remaining in the body.

Option B: Vitamin K is the antidote for warfarin (Coumadin), not heparin. It works by promoting the synthesis of vitamin K-dependent clotting factors in the liver, a process that takes several hours to days.
Option C: Aspirin is an antiplatelet drug, not an antidote. It works by irreversibly inhibiting cyclooxygenase (COX) enzymes in platelets, which prevents the formation of thromboxane A2 and subsequent platelet aggregation.
Option D: Warfarin is an oral anticoagulant itself, not an antidote. It inhibits the synthesis of vitamin K-dependent clotting factors. Administering it would worsen, not reverse, the effects of another anticoagulant.

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.
Heparin is a high-alert medication due to the significant risk of bleeding. Nurses must be able to recognize signs of overdose (e.g., hematuria, melena, petechiae) and know the correct reversal agent.
When administering protamine sulphate, the nurse must infuse it slowly (e.g., not exceeding 50 mg over 10 minutes) to prevent adverse reactions such as severe hypotension, bradycardia, and anaphylaxis.
What if? If a patient on heparin develops heparin-induced thrombocytopenia (HIT), protamine sulfate is NOT used. Instead, heparin is stopped immediately, and an alternative anticoagulant like argatroban (a direct thrombin inhibitor) is started.

How to Approach the Question

This is a direct factual recall question common in pharmacology.
First, identify the key drug in the question stem, which is 'heparin'.
Next, the question asks for the 'antidote', which is a substance that counteracts a poison or drug's effects.
Systematically review your knowledge of common anticoagulants and their specific reversal agents.
Evaluate the given options: Protamine sulphate is the known antidote for heparin. Vitamin K is for warfarin. Aspirin and Warfarin are not antidotes for heparin.
Select the option that correctly matches the drug with its antidote.

Concept Tested & Keywords

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E6 Pharmacology Nursing Lilley 11e Part 2 pp. 108-110, 123-125

E6 Pharmacology Katzung 16e p. 958-960

Practise the full PGIMER Sangrur NO - 2023

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