Should losartan (Angiotensin II Receptor Blocker) be held in a patient with Acute Kidney Injury (AKI)?

Management of Losartan in Acute Kidney Injury

Losartan should be temporarily discontinued in patients with acute kidney injury until renal function has returned to baseline or stabilized. 1, 2

Rationale for Holding Losartan During AKI

Angiotensin II receptor blockers (ARBs) like losartan can worsen kidney function during episodes of acute kidney injury through several mechanisms:

1. Direct impact on renal hemodynamics:

   • Losartan blocks the effects of angiotensin II, which normally helps maintain glomerular filtration pressure during states of decreased renal perfusion
   • This can lead to further deterioration of renal function in AKI 2

2. FDA labeling specifically warns:

   • "Changes in renal function including acute renal failure can be caused by drugs that inhibit the renin-angiotensin system" 2
   • "Consider withholding or discontinuing therapy in patients who develop a clinically significant decrease in renal function on losartan" 2

3. Risk factors for worsened renal function:

   • Patients with volume depletion
   • Those with renal artery stenosis
   • Patients with severe heart failure
   • Concurrent use of other nephrotoxic medications 2, 3

Clinical Evidence of Risk

Multiple case reports demonstrate that losartan can cause reversible acute renal failure, particularly in high-risk patients:

• Patients with renal artery stenosis 4, 5
• Those with solitary kidneys 4
• Patients with pre-existing renal insufficiency 3
• Transplant recipients 5

These cases consistently show that renal function improves after discontinuation of losartan, supporting the recommendation to hold the medication during AKI.

Management Algorithm for Losartan in AKI

1. Immediately upon AKI diagnosis:

   • Hold losartan completely
   • Correct any volume depletion
   • Monitor renal function and potassium levels closely 1, 2

2. During AKI recovery:

   • Continue to hold losartan until renal function returns to baseline or stabilizes
   • Ensure adequate volume status and blood pressure control using alternative agents if needed 1

3. After AKI resolution:

   • Wait until renal function has stabilized
   • Consider restarting at a lower dose than previously used (25-50% of previous dose)
   • Monitor renal function and potassium within 2-4 weeks after restarting 1
   • A small rise in serum creatinine (10-20%) may be acceptable when restarting 1

Special Considerations

• Volume status assessment is critical before restarting losartan after AKI
• Avoid concurrent nephrotoxic medications (especially NSAIDs) when restarting losartan
• Potassium monitoring is essential as hyperkalemia is a risk with losartan, particularly after AKI 2
• Patients with bilateral renal artery stenosis or stenosis in a solitary kidney are at particularly high risk and may require permanent discontinuation 3

Long-term Considerations

While losartan may have potential benefits in preventing chronic kidney disease progression after AKI recovery 6, the immediate priority during active AKI is to remove factors that may worsen kidney function. The long-term benefits can only be realized after successful recovery from the acute episode.