A patient who has received heparin for prophylactic against deep venous thrombosis (DVT) in bleeding. Which of the following is the antidote for a patient with overdose of heparin?

Appeared in: RML Lucknow - 2021

Explanation

Protamine Sulphate is the specific and rapid-acting antidote for heparin overdose.
It functions as a heparin antagonist due to its chemical properties. Protamine is a strongly basic (positively charged) peptide.
Heparin is a strongly acidic (negatively charged) molecule. The positive charge of protamine binds to the negative charge of heparin, forming a stable and inactive salt complex.
This binding neutralizes the anticoagulant effect of heparin, typically within 5 minutes of administration.
The standard dosing is approximately 1 mg of protamine sulphate to neutralize 100 units of heparin.

Option B: Vitamin K is the antidote for the oral anticoagulant warfarin (Coumadin), not heparin. It works by a different mechanism and on a much slower timescale.
Option C: Atropine Sulphate is an anticholinergic drug. It is used to treat symptomatic bradycardia and is also the antidote for organophosphate or carbamate poisoning.
Option D: Physostigmine is a cholinesterase inhibitor. Its primary use is as an antidote for poisoning with anticholinergic drugs (like an atropine overdose).

Clinical Relevance

Nursing practice connection: Use the key finding related to Pharmacological Antidotes for Anticoagulants to guide bedside assessment, documentation, and the next nursing action.
Knowing the correct antidote for high-alert medications like heparin is a critical patient safety competency for nurses, as rapid reversal can be life-saving in cases of severe bleeding.
Nurses must monitor the activated Partial Thromboplastin Time (aPTT) for patients on heparin and the Prothrombin Time/International Normalized Ratio (PT/INR) for patients on warfarin to ensure therapeutic levels and prevent overdose.
What if? If the patient experienced an overdose of a low-molecular-weight heparin (LMWH) like enoxaparin, protamine sulphate would still be the antidote, but it may only partially reverse the effects. The dosage is typically 1 mg of protamine for every 1 mg of enoxaparin.

How to Approach the Question

First, identify the key terms in the question: 'heparin', 'overdose', and 'antidote'.
This is a factual recall question that tests your knowledge of pharmacology, specifically anticoagulants and their reversal agents.
Systematically review the options provided.
Recall or deduce the primary use and antidote relationship for each drug listed. Protamine Sulphate is specifically paired with heparin.
Eliminate the other options by identifying their correct indications: Vitamin K for warfarin, Atropine for cholinergic crisis/bradycardia, and Physostigmine for anticholinergic toxicity.
Confirm that Protamine Sulphate is the correct and specific antidote for heparin.

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 RML Lucknow - 2021

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