The first choice of drug for treating MI?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Pharmacology

Easy

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

Streptokinase is a thrombolytic (fibrinolytic) agent used for reperfusion therapy in ST-elevation myocardial infarction (STEMI).
Its primary action is to dissolve the fibrin clot obstructing the coronary artery, thereby restoring blood flow to the heart muscle.
This is considered a definitive treatment for the underlying cause of the MI, especially when primary percutaneous coronary intervention (PCI) is not immediately available.
It acts by promoting the conversion of plasminogen to plasmin, which then breaks down the fibrin matrix of the thrombus.

Option A: This is an aminoglycoside antibiotic used to treat bacterial infections, primarily tuberculosis. It has no role in the management of myocardial infarction.
Option C: This is a vasodilator used as a first-line agent for relieving ischemic chest pain (angina). It reduces myocardial oxygen demand but does not dissolve the underlying clot, making it a symptomatic treatment, not a definitive one.
Option D: This is an anticoagulant that prevents the formation of new clots and the extension of existing ones. It is used as an adjunctive therapy with thrombolytics or PCI but does not actively dissolve an already-formed clot.

Clinical Relevance

Nursing practice connection: Knowing Pharmacological management of Myocardial Infarction (MI) helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
The core principle in treating STEMI is 'time is muscle.' Rapid administration of reperfusion therapy, whether via thrombolytics or PCI, is critical to salvaging heart tissue and improving patient outcomes.
Nurses play a vital role in screening patients for contraindications to thrombolytic therapy, such as a history of hemorrhagic stroke, recent surgery, or active bleeding, to prevent life-threatening complications.
What if? If a patient with STEMI presents to a hospital without PCI capability and has a high risk of bleeding (e.g., recent major surgery), thrombolytic therapy like Streptokinase would be contraindicated. The priority would be immediate transfer to a PCI-capable center.

How to Approach the Question

First, identify the core pathology of the question: Myocardial Infarction (MI) is caused by a blood clot (thrombus) blocking a coronary artery.
Next, analyze the question's intent. 'First choice of drug for treating MI' asks for the definitive therapy that addresses the cause, not just the symptoms.
Categorize each drug option by its pharmacological class: Streptomycin (antibiotic), Streptokinase (thrombolytic), Nitroglycerin (vasodilator), Heparin (anticoagulant).
Evaluate which drug class directly targets the thrombus. A thrombolytic is the only class listed that dissolves an existing clot.
Differentiate this from drugs for symptom relief (Nitroglycerin) or prevention of further clotting (Heparin) to select the most appropriate answer for treating the MI.

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 520-522

E6 Medicine Harrison 22e Part 2 pp. 25-27, 22-24