What if a patient on losartan (angiotensin II receptor antagonist) develops hyperkalemia?

From the Guidelines

If a patient on losartan develops hyperkalemia, the medication should be discontinued or the dose reduced, especially if potassium levels exceed 5.5 mEq/L. This approach is based on the expert consensus document on the management of hyperkalaemia in patients with cardiovascular disease treated with renin angiotensin aldosterone system inhibitors, as outlined in the European Heart Journal 1. The management of hyperkalemia involves a multifaceted approach, including:

• Restricting dietary potassium intake
• Discontinuing other medications that can raise potassium, such as potassium supplements, NSAIDs, and potassium-sparing diuretics
• Monitoring renal function
• Considering alternative antihypertensive medications, such as calcium channel blockers (e.g., amlodipine 5-10 mg daily) or thiazide diuretics (e.g., hydrochlorothiazide 12.5-25 mg daily) For severe hyperkalemia (>6.0 mEq/L), urgent medical attention is necessary, with treatments like intravenous calcium gluconate, insulin with glucose, or sodium bicarbonate 1. Losartan causes hyperkalemia by blocking angiotensin II receptors, which reduces aldosterone production, leading to potassium retention 1. Patients with reduced kidney function, diabetes, or those taking other medications affecting potassium levels are at higher risk and require closer monitoring of potassium levels, particularly during the first few weeks of therapy and after any dose adjustments. The use of potassium binders, such as patiromer sorbitex calcium (Veltassa) or sodium zirconium cyclosilicate (ZS-9), may be considered to enable patients to continue renin-angiotensin-aldosterone system inhibitor therapy while managing hyperkalemia 1. It is essential to closely monitor potassium levels and adjust treatment accordingly to prevent hypokalemia, which can be more dangerous than hyperkalemia. In patients with potassium levels between 4.5 and 5 mEq/L, it is recommended to titrate or start renin-angiotensin-aldosterone system inhibitor therapy and closely monitor potassium levels, initiating potassium-lowering measures if levels exceed 5.0 mEq/L 1.

From the FDA Drug Label

7.1 Agents Increasing Serum Potassium Coadministration of losartan with other drugs that raise serum potassium levels may result in hyperkalemia. Monitor serum potassium in such patients. 5.4 Hyperkalemia Monitor serum potassium periodically and treat appropriately. Dosage reduction or discontinuation of losartan may be required

If a patient on losartan develops hyperkalemia, the following steps should be taken:

• Monitor serum potassium periodically
• Treat hyperkalemia appropriately
• Consider dosage reduction or discontinuation of losartan 2, 2

From the Research

Hyperkalemia in Patients on Losartan

• Hyperkalemia is a potential complication of losartan, an angiotensin II receptor antagonist, especially when used in combination with other medications such as spironolactone 3.
• A case report described an 84-year-old female patient who developed severe hyperkalemia (8.4 mEq/l) while being treated with losartan and spironolactone, requiring hemodialysis and ventilatory assistance 3.
• The use of losartan can increase the risk of hyperkalemia, particularly in patients with decreased renal function 4, 5.

Risk Factors for Hyperkalemia

• Decreased renal function, expressed as estimated glomerular filtration rate (eGFR) <50 ml/min, is a significant risk factor for hyperkalemia in patients using potassium-influencing drugs, including losartan 4.
• Other risk factors, such as diabetes mellitus, congestive heart failure, advanced age, and use of certain medications, may also contribute to the development of hyperkalemia 4, 5.

Management and Prevention of Hyperkalemia

• Traditional management steps for hyperkalemia include reducing dietary potassium, discontinuing potassium supplements, and using medications such as intravenous calcium gluconate, insulin, and glucose 5.
• New oral therapies, such as patiromer calcium and ZS-9, may provide a greater margin of safety for patients with combined heart and kidney disease 5.
• Close monitoring of serum potassium and assessment of trans-tubular potassium gradient (TTKG) and fractional excretion of potassium (FEK) before starting therapy can help identify patients at higher risk of developing hyperkalemia 6.