From the Guidelines
Losartan can cause hyperkalemia, as it is an angiotensin II receptor antagonist that can increase potassium levels by reducing aldosterone-mediated potassium excretion. This is supported by a 2018 expert consensus document on the management of hyperkalaemia in patients with cardiovascular disease treated with renin angiotensin aldosterone system inhibitors, which lists angiotensin receptor blockers as one of the drugs that may cause hyperkalemia 1. The incidence of hyperkalemia with Losartan monotherapy is generally low, but it can increase to 5% with dual renin angiotensin aldosterone system inhibition and to 5-10% in patients with heart failure or chronic kidney disease.
Key points to consider when prescribing Losartan include:
- Monitoring potassium levels regularly, especially in patients with kidney impairment, diabetes, or those taking potassium supplements or potassium-sparing diuretics
- Advising patients to avoid high-potassium foods and potassium-containing salt substitutes
- Being aware of the signs of hyperkalemia, such as muscle weakness, fatigue, numbness, and cardiac arrhythmias
- Considering dose reduction or discontinuation if hyperkalemia develops, particularly in high-risk patients
According to the 2018 expert consensus document, 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 potassium-lowering agents such as loop diuretics and potassium binders may be necessary to manage hyperkalemia. It is essential to weigh the benefits of Losartan against the potential risk of hyperkalemia and to closely monitor patients for signs of elevated potassium levels.
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, although the incidence may vary depending on several factors, including patient population and dosage 3, 4.
- Studies have shown that the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs), such as losartan, can be associated with hyperkalemia, particularly in patients with chronic renal insufficiency 3.
- A study comparing the effect of an ACEI (Lisinopril) to an ARB (Losartan) on serum potassium levels found that both drugs can increase the risk of hyperkalemia, especially in patients with high normal serum potassium levels 5.
- Another study found that high-dose losartan (150 mg/d) increased the risk of hyperkalemia compared to low-dose losartan (50 mg/d) in patients with heart failure 4.
- However, it's worth noting that the risk of hyperkalemia associated with losartan may be lower compared to ACEIs, and that the benefits of losartan in reducing cardiovascular risk may outweigh the risks of hyperkalemia in many patients 3, 4.
- Factors that increase the risk of hyperkalemia in patients taking losartan include: