Loop Diuretics and Digitalis Toxicity

A hypertensive patient taking a loop diuretic has an increased risk of developing electrolyte imbalances, particularly hypokalemia. If your patient also has heart failure and is taking a digitalis glycoside, such as digoxin, and a loop diuretic, he has an increased risk of developing digitalis toxicity.

Be alert for the following signs and symptoms of digitalis toxicity:

• anorexia, nausea, vomiting, diarrhea, and abdominal pain
• headache, restlessness, irritability, depression, personality changes, lethargy, confusion, disorientation, insomnia, psychosis, and seizures
• atrial or ventricular arrhythmias, heart block, accelerated junctional rhythms, and atrial tachycardia with atrioventricular block
• blurred vision, flickering lights, white borders around dark objects, and colored dots.

Also, obtain your patient’s baseline serum potassium level and monitor his serum potassium and digitalis levels. To ensure the accuracy of his serum digitalis level, obtain the sample at least 8 hours after the last dose, preferably before administering a daily oral maintenance dose.