Cardiac Glycoside– Digoxin
How it works? “Action”
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Adverse Reactions
Inhibits sodium-potassium adenosine triphosphatase
pump, increases cellular sodium and calcium
concentrations
o Increase cardiac contractility of the heart
muscle (positive inotropic effect)
o Slows conduction velocity through the AV
node (negative dromotropic effect)
o Decrease in heart rate (negative chronotropic
effect)
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Headache
Weakness, drowsiness
Visual disturbances: colored vision (seeing green,
yellow, purple), halo vision
Dysrhythmias including bradycardia or tachycardia
Nausea, vomiting
Anorexia, nausea, vomiting, blurred vision, or
yellowish vision may be initial indicators of toxicity.
Indications
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Heart failure
Atrial fibrillation
Contraindications
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Drug allergy
Digitalis toxicity
Heart block
Ventricular dysrhythmias
Use with diuretics (risks of hypokalemia)
Digoxin Toxicity
• Life threatening toxic effects to the heart
• Very narrow therapeutic window
• Drug levels must be monitored.
• Electrolyte levels must be monitored.
What increases risk of toxicity?
• Increased age, low K+ and Mg+, hypoxia,
hypothyroidism
What do we do if we observe these signs?
• Hold dose, report!
What is antidote for digoxin?
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Digoxin immune Fab (Digifab)- Digibind
Nursing Management
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Digitalization is providing a loading dose of digoxin to a client to rapidly reach a therapeutic drug level.
Steady serum levels take about 1 week to achieve maximum effect, normally doses given ~ 6-8 hours apart over 24 hours.
ECG monitoring when digitalized, related to risk for toxicity and dysrhythmias.
Digoxin has a very narrow therapeutic window, range of drug levels in the blood that is considered therapeutic is small (0.8 – 2.0 nmol/L).
ASSESS client prior to administering medication:
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BP, HR (apical & radial), heart sounds, ECG, breath sounds, peripheral pulse location and grading, capillary refill, presence of edema.
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Apical pulse for 1 full minute* before administering.
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Apical pulse rate below 60 bpm or greater than 100 bpm- hold drug and notify primary care provider!
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Give with meals.
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Daily weights
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Intake and output
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Electrolyte levels (especially K+ level); K+ between 3.5-5 mmol/L, Na+ 135-145 mmol/L, Cl- 98-106 mmol/L, Ca+ 2.25-2.75 mmol/L, Mg+ 0.65-1.05
mmol/L
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Kidney (BUN, CR, eGFR) and liver (AST, ALT, ALP) function tests
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Medication and dietary history (including usual amount of bran ingested)
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Smoking and alcohol intake
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Assess plasma drug levels of digoxin (usually between 0.8-2.0 ng per mL)
Reference
Sealock, K., Seneviratne, C. Lilley, L.L., & Snyder, J. S. (2021). Lilley’s pharmacology for Canadian health care practice (4th ed.). Elsevier.