From the Guidelines
Digoxin is contraindicated in patients with hyperkalemia due to the increased risk of digoxin toxicity and potentially fatal cardiac arrhythmias. The interaction between digoxin and hyperkalemia is particularly concerning because both conditions can affect cardiac conduction and rhythm, creating a potentially synergistic negative effect on cardiac function 1. When potassium levels are already high (hyperkalemia), digoxin's effects are potentiated, significantly increasing the risk of digoxin toxicity.
Key Considerations
- Patients with elevated potassium levels should not be given digoxin due to the dangerous interaction between these two factors.
- Even patients already on digoxin therapy should have their medication held if hyperkalemia develops, and the elevated potassium should be treated promptly.
- The hyperkalemia must be corrected before digoxin can be safely administered or resumed.
- Healthcare providers should monitor potassium levels closely in all patients receiving digoxin therapy.
Management of Hyperkalemia
- In patients with hyperkalemia, an evaluation should be made of the patient’s diet, use of supplements, salt substitutes, and nutraceuticals that contain K+ as well as of concomitant medications that may contribute to hyperkalemia 1.
- Co-administration of drugs known to promote hyperkalemia or reduce kidney function are not absolute contraindications but should prompt more frequent monitoring of K+ levels.
- A low-K+ diet and loop or thiazide diuretics that increase K+ excretion to reduce the occurrence of hyperkalemia may be considered.
Treatment of Digoxin Toxicity
- Digoxin-specific antibody (Fab) is a monovalent immunoglobulin that rapidly binds to intravascular digoxin and can be used to treat digoxin toxicity 1.
- Clinical response rates to digoxin Fab are as high as 80% to 90%, particularly in the acute setting.
- Patients with hyperkalemia or arrhythmias in the setting of digoxin serum levels of >2 mcg/L are at increased risk of death.
From the FDA Drug Label
Severe digitalis intoxication can cause a massive shift of potassium from inside to outside the cell, leading to life-threatening hyperkalemia. The administration of potassium supplements in the setting of massive intoxication may be hazardous and should be avoided Hyperkalemia caused be massive digitalis toxicity is best treated with DIGIBIND; initial treatment with glucose and insulin may also be required if hyperkalemia itself is acutely life-threatening.
Digoxin and Hyperkalemia:
- Digoxin is not absolutely contraindicated with hyperkalemia, but severe digitalis intoxication can cause life-threatening hyperkalemia.
- In the setting of massive digitalis intoxication, administration of potassium supplements may be hazardous and should be avoided.
- Hyperkalemia caused by massive digitalis toxicity is best treated with DIGIBIND 2.
From the Research
Digoxin and Hyperkalemia
- Digoxin is an inhibitor of the sodium-potassium ATPase, and in overdose, hyperkalemia is common 3.
- Hyperkalemia is often treated with intravenous calcium, but it is traditionally contraindicated in digoxin toxicity 3, 4.
- However, studies have shown that intravenous calcium does not seem to cause malignant dysrhythmias or increase mortality in digoxin-intoxicated patients 3, 4.
- In fact, calcium gluconate is recommended for membrane stabilization in the treatment of hyperkalemia, unless the patient is in cardiac arrest 5.
Treatment of Hyperkalemia in Digoxin Toxicity
- Treatment of hyperkalemia includes measures to stabilize cardiac membranes, shift potassium from extracellular to intracellular stores, and promote potassium excretion 5.
- Digoxin-specific Fab fragments are recommended for the treatment of digoxin toxicity, as they can quickly reverse digitalis-induced dysrhythmias, hyperkalemia, and myocardial depression 6, 7.
- Other treatments for hyperkalemia, such as beta-agonists, intravenous insulin, and dialysis, may also be effective 5.
Importance of Early Diagnosis and Treatment
- Early diagnosis and treatment of digoxin toxicity are crucial, as mortality increases in patients exhibiting certain prognostic factors, including hyperkalemia 6.
- A high index of suspicion for digoxin toxicity is important in patients with refractory hyperkalemia, as it can be a potential cause of this condition 7.