Drugs used to counteract the bleeding complication due to heparin overdose?

Appeared in: BCCL kharkhanda Staff Nurse - 2015

Explanation

Protamine sulphate is the specific antidote for heparin overdose.
It is a polycationic (positively charged) peptide that has a strong affinity for the anionic (negatively charged) heparin molecule.
This binding forms a stable, inactive salt complex, which neutralizes the anticoagulant effect of heparin.
The reversal of heparin's effects occurs rapidly, within 5 minutes of intravenous administration of protamine sulphate.

Option A: Calcium gluconate is used to treat conditions like hypocalcemia, magnesium toxicity, or hyperkalemia by providing calcium ions. It does not interact with or reverse the effects of heparin.
Option C: Methargine (a brand name for methylergometrine) is a uterine stimulant. It works by causing smooth muscle contraction in the uterus to control bleeding after childbirth. It has no effect on the systemic coagulation cascade.
Option D: Nitrofurantoin is an antibiotic used to treat urinary tract infections. It has antimicrobial properties but no hematological effects related to coagulation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacology: Antidotes for Anticoagulants as background academic context rather than a clinical decision trigger.
A nurse must be able to quickly recognize signs of heparin overdose (e.g., hematuria, melena, petechiae, unexplained bleeding) and anticipate the order for protamine sulphate.
When administering protamine sulphate, the nurse should infuse it slowly (not exceeding 50 mg over 10 minutes) to prevent adverse reactions like hypotension, bradycardia, and anaphylaxis.
The dosage of protamine sulphate is critical and is based on the amount of heparin the patient has received. Typically, 1 mg of protamine neutralizes approximately 100 units of heparin.

How to Approach the Question

First, identify the core of the question: it asks for the antidote to a specific drug, heparin.
This is a factual recall question common in pharmacology. You need to access your knowledge of drug classes and their specific reversal agents.
Evaluate each option. Protamine sulphate is known as the classic heparin antagonist.
Consider the other options to confirm they are incorrect. Calcium gluconate is for electrolyte imbalances, Methargine is for postpartum hemorrhage, and Nitrofurantoin is a UTI antibiotic.
Confirm your initial choice. The direct pharmacological relationship between heparin and protamine sulphate makes it the only correct answer.

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 BCCL kharkhanda Staff Nurse - 2015

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