From the Guidelines
Losartan can cause hyperkalemia, as it is an angiotensin II receptor antagonist that can decrease potassium excretion, leading to elevated potassium levels in the blood. This is supported by a study published in the European Heart Journal in 2018 1, which lists renin-angiotensin-aldosterone inhibitors, including angiotensin receptor blockers like Losartan, as drugs that may cause hyperkalemia. The study notes that the incidence of hyperkalemia with RAASi monotherapy is less than 2% in hypertensive patients without risk factors, but increases to 5% with dual RAAS inhibition and to 5-10% when dual therapy is administered in patients with heart failure or chronic kidney disease.
Key points to consider when prescribing Losartan include:
- Monitoring potassium levels regularly, especially when starting therapy or adjusting dosage
- Being aware of the increased risk of hyperkalemia in patients with kidney impairment, diabetes, or those taking other medications that can raise potassium levels
- Typical signs of hyperkalemia include muscle weakness, fatigue, numbness, and in severe cases, cardiac arrhythmias
- If hyperkalemia develops, dose reduction or discontinuation of Losartan may be necessary, along with dietary potassium restriction
It's also important to note that life-threatening hyperkalemia requires immediate treatment with a combination of calcium carbonate and hyperosmolar sodium, as well as insulin and/or beta adrenoceptor agonists to transfer potassium into cells 1. However, these treatments only provide temporary benefit, and treatment with a potassium-lowering agent should be initiated as early as possible to manage hyperkalemia.
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. 5.4 Hyperkalemia Monitor serum potassium periodically and treat appropriately. Dosage reduction or discontinuation of losartan may be required 7. 4 Dual Blockade of the Renin-Angiotensin System (RAS) Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, syncope, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy
Losartan can cause hyperkalemia, especially when used with other drugs that raise serum potassium levels or in patients with certain medical conditions, such as renal impairment.
- Key points:
From the Research
Losartan and Hyperkalemia
- Losartan, an angiotensin II receptor antagonist, can cause hyperkalemia, especially when used with potassium-sparing diuretics such as spironolactone or triamterene 3.
- The incidence of hyperkalemia in high-risk patients during treatment with losartan versus an angiotensin converting enzyme inhibitor (Lisinopril) has been studied, highlighting the potential risk of hyperkalemia with losartan 4.
- A case report describes a patient who developed severe hyperkalemia associated with the use of losartan and spironolactone, requiring hemodialysis and ventilatory assistance 5.
- In pediatric kidney transplant recipients, losartan and enalapril may be associated with serious adverse events, including hyperkalemia and life-threatening acidosis 6.
Mechanism and Risk Factors
- The mechanism of losartan-induced hyperkalemia is related to its effect on the renin-angiotensin-aldosterone system, which can lead to increased potassium levels 3.
- The risk of hyperkalemia with losartan is increased in patients with renal failure or liver dysfunction, and in those taking potassium-sparing diuretics or other medications that can increase potassium levels 3, 6.