At what level of impaired renal function, specifically decreased glomerular filtration rate (GFR), should Losartan (Angiotensin II receptor antagonist) be discontinued?

From the Guidelines

Losartan should not be routinely discontinued in people with GFR < 30 ml/min/1.73 m2 as it remains nephroprotective, according to the most recent and highest quality study 1.

Key Considerations

• The decision to discontinue losartan should be individualized based on the patient's overall clinical picture, including the presence of proteinuria, heart failure, or other conditions where ARBs provide specific benefits.
• Close monitoring of kidney function and potassium levels is essential for patients with reduced GFR.
• Losartan, an angiotensin II receptor blocker (ARB), can worsen kidney function in patients with severe renal impairment by reducing glomerular pressure too much, but the benefits of continued use often outweigh the risks.

Clinical Guidance

• For patients with GFR < 45 ml/min/1.73 m2, losartan should be started at a lower dose and GFR and serum potassium should be assessed within 1 week of starting or following any dose escalation 1.
• The use of losartan in patients with GFR < 30 ml/min/1.73 m2 is supported by recent studies, which suggest that the benefits of continued use outweigh the risks 1.
• Alternative blood pressure medications, such as certain calcium channel blockers or appropriate-dose diuretics, may be considered for patients who cannot tolerate losartan, but the decision to discontinue losartan should be made on a case-by-case basis.

From the FDA Drug Label

1. 3 Renal Function Deterioration Changes in renal function including acute renal failure can be caused by drugs that inhibit the renin-angiotensin system and by diuretics. Patients whose renal function may depend in part on the activity of the renin-angiotensin system (e.g., patients with renal artery stenosis, chronic kidney disease, severe congestive heart failure, or volume depletion) may be at particular risk of developing acute renal failure on losartan. Monitor renal function periodically in these patients Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function on losartan

The specific GFR value at which losartan should be discontinued is not provided in the drug label.

• Discontinuation of losartan is recommended when patients develop a clinically significant decrease in renal function. However, the label does not define what constitutes a clinically significant decrease in terms of GFR. Therefore, no specific GFR value can be determined for discontinuing losartan based on the provided information 2.

From the Research

Losartan Discontinuation Based on GFR

• The studies provided do not specify a particular GFR value at which losartan should be discontinued 3, 4, 5, 6, 7.
• However, it is noted that losartan can cause a decrease in GFR, particularly at higher doses 4, 6.
• A study found that losartan 100 mg daily lowered GFR by 4 ml/min/1.73 m^2 4.
• Another study found that the greater the acute fall in eGFR during losartan treatment, the slower the rate of long-term eGFR decline 5.
• It is also noted that losartan can cause an increase in serum creatinine, which can be a marker of decreased renal function 6.
• The decision to discontinue losartan based on GFR should be made on a case-by-case basis, taking into account the individual patient's renal function and overall health status.

Factors to Consider

• The dose of losartan being used, as higher doses may be more likely to cause a decrease in GFR 4, 6.
• The patient's underlying renal function and any pre-existing kidney disease 3, 7.
• The presence of other factors that may affect renal function, such as diabetes or hypertension 4, 5.
• The patient's overall health status and any other medications they may be taking 3, 7.