Cardiac glycosides: Nursing pharmacology

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digoxin (Lanoxin)
*High Alert Medication*

Cardiac glycoside
  • Inhibit Na+/K+ ATPase, which interrupts the Na+/Ca2+ exchanger
  • Increase in intracellular calcium, which increases the force of contraction of cardiac muscle and the cardiac output
  • Stimulates the vagus nerve and increases the refractory period of the AV node, thereby reducing AV node conduction velocity and decreasing the heart rate
  • Atrial arrhythmias (i.e., atrial flutter and atrial fibrillation)
  • Heart failure
  • PO
  • IV
  • IM (not preferred)
  • Gastrointestinal disturbances ( i.e., nausea, vomiting, anorexia, and rarely diarrhea)
  • Neurologic symptoms (i.e., confusion and disorientation)
  • Bradycardia, heart block, arrhythmia
  • Visual disturbances (i.e., diplopia, blurred vision, xanthopsia)
  • Hyperkalemia
  • Heart blocks, ventricular arrhythmia, myocardial infarction

Use with caution
  • Hypokalemia, hypomagnesemia, hypercalcemia
  • Renal dysfunction
  • Along with medications like amiodarone, verapamil, diltiazem, and quinidine
  • Weight
  • Vital signs
  • Heart and lung sounds
  • Location and extent of edema
  • Laboratory test results
    • BNP, ANP
    • Electrolytes, especially potassium
    • Renal function tests
  • Diagnostic tests
  • ECG
  • Ejection fraction

IV administration
  • Assess apical pulse for one full minute, continuous ECG
  • Monitor for arrhythmias, signs of toxicity
  • Have digoxin immune Fab readily available

Evaluate for:
  • decrease in signs and symptoms of heart failure
  • absence of side effects
  • improved quality of life
  • Purpose of medication: to help heart to beat more effectively
  • Take medication as prescribed, at the same time every day, do not stop abruptly
  • Self-monitoring of pulse: count for a full minute; do not take medication if the heart rate is less than 60 beats per minute
  • Follow their healthcare regimen; e.g., moderate physical activity, low sodium and low fat diet
  • Maintain normal potassium; include potassium rich foods in daily diet; e.g., bananas, oranges, broccoli, and potatoes
  • Recognize symptoms of hypokalemia; e.g., muscle twitches, weakness, fatigue
    • Contact their healthcare provider immediately
  • Recognize symptoms of digoxin toxicity; e.g., anorexia, nausea, vomiting, visual disturbances
    • Contact their healthcare provider immediately

Memory Anchors and Partner Content


Cardiac glycosides, also called digitalis glycosides, are medications derived from the foxglove plant, Digitalis purpurea. They are commonly used for the treatment of atrial arrhythmias, such as atrial flutter and atrial fibrillation, which are caused by rapid, uncoordinated contractions of the atria. In addition, cardiac glycosides can be prescribed for congestive heart failure when other medications fail.

Now, the most commonly used cardiac glycoside is digoxin, which can be given orally, intravenously, and intramuscularly. Once administered, digoxin works by reversibly inhibiting the sodium-potassium ATPase located in the cell membrane of cardiomyocytes.

Normally the sodium-potassium ATPase pumps three sodium ions out of the cell for every two potassium ions that it pumps in, and to do this, it consumes one ATP molecule for energy.

When the sodium-potassium ATPase is inhibited by digoxin, sodium builds up inside the cell. This interrupts the sodium-calcium exchanger on the cell membrane, which normally pumps one calcium ion out in exchange for three sodium ions.

As a result, digoxin causes calcium to build up within cardiomyocytes, allowing the cardiac muscle fibers to contract more efficiently, which leads to an increase in the force of the heart’s contractions and cardiac output. In turn, the increase in cardiac output increases the renal blood flow and urine output, which also helps reduce peripheral edema.

Digoxin also stimulates the vagus nerve, which provides the parasympathetic supply to the heart, and reduces the conduction velocity through the AV node. These two effects combined result in a decreased heart rate. But because parasympathetic innervation is much richer in the atria, these effects mainly involve the atria.


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