Digoxin is administered intravenously to the patient as the drug acts to?

Appeared in: BCCL kharkhanda Staff Nurse - 2015

Explanation

Digoxin is classified as a cardiac glycoside and a positive inotropic agent.
Its primary mechanism of action is to inhibit the Na+/K+-ATPase pump in cardiac muscle cells.
This inhibition leads to an increase in intracellular calcium, which enhances the force and velocity of myocardial contraction.
This increased contractility improves cardiac output, making it a key treatment for heart failure.

Option A: Digoxin does not primarily dilate coronary arteries. This action is characteristic of nitrates (e.g., nitroglycerin).
Option C: While Digoxin does decrease electrical conductivity through the AV node (a negative dromotropic effect), this is considered a secondary effect. The primary therapeutic action, especially in heart failure, is its effect on contractility.
Option D: Digoxin is used to control the rate in certain dysrhythmias (like atrial fibrillation) but is not a primary antiarrhythmic. Furthermore, Digoxin toxicity is a common cause of new and dangerous cardiac dysrhythmias.

Clinical Relevance

Nursing practice connection: Use the key finding related to Mechanism of Action of Digoxin to guide bedside assessment, documentation, and the next nursing action.
A critical nursing responsibility is to assess the patient's apical pulse for one full minute before administering Digoxin. The dose should be held and the provider notified if the heart rate is below 60 bpm for an adult.
Nurses must educate patients on the signs of toxicity (nausea, vomiting, vision changes) and the importance of regular follow-up and blood tests due to the drug's narrow therapeutic index.
Hypokalemia (low potassium) potentiates the effect of Digoxin and increases the risk of toxicity. Therefore, monitoring serum potassium levels is crucial, especially in patients also taking diuretics.

How to Approach the Question

First, identify the drug mentioned in the stem: Digoxin.
Recall the drug class for Digoxin (cardiac glycoside, positive inotrope) and its primary mechanism of action.
The primary action of Digoxin is to increase the force of heart muscle contraction (positive inotropy).
Evaluate each option against this primary mechanism. Option B directly states this primary action.
Consider the other options. While Digoxin does affect heart rate and conduction (Option C), its main purpose is to improve contractility. It does not dilate coronary arteries (Option A). Its effect on dysrhythmias (Option D) is a consequence of its rate-slowing properties, not its primary action.

Concept Tested & Keywords

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E6 Pharmacology KD Tripathi Essentials 9e Part 2 p. 188-190

E6 Pharmacology Nursing Lilley 11e Part 2 p. 73-75

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