Losartan Autoimmune Disease Considerations: A Clinical Guide

Does losartan treat autoimmune disease?

No. Losartan is an angiotensin II receptor blocker approved for hypertension in adults and children 6 years and older, stroke risk reduction in hypertension with left ventricular hypertrophy, and diabetic nephropathy with elevated serum creatinine and proteinuria in type 2 diabetes with a history of hypertension [1]. None of these is an autoimmune condition.

Losartan may be prescribed to a person with an autoimmune condition for a labeled use, such as hypertension or diabetic nephropathy, but the label does not indicate it for treating the autoimmune disease itself [1]. The kidney indication is written for diabetic nephropathy with a urinary albumin to creatinine ratio of 300 mg/g or more [1].

What does the label say about kidneys and potassium?

The renal warning says changes in renal function, including acute renal failure, can occur with drugs that inhibit the renin-angiotensin system, and that patients whose kidney function depends in part on it (renal artery stenosis, chronic kidney disease, severe heart failure, volume depletion) may be at particular risk. The label says to monitor renal function periodically and to consider withholding or discontinuing therapy after a clinically significant decrease [1].

The label says to monitor serum potassium periodically and treat appropriately, and that dosage reduction or discontinuation may be required [1]. In RENAAL (1513 patients with type 2 diabetic nephropathy), hyperkalemia was reported in at least 4% of losartan patients and at least 2 percentage points more than placebo [1].

Which interactions does the label list?

The label names four groups: drugs that raise serum potassium, lithium (monitor levels), NSAIDs including selective COX-2 inhibitors, and dual renin-angiotensin blockade with ACE inhibitors, other ARBs or aliskiren [1]. For NSAIDs, it warns that in elderly, volume-depleted or kidney-impaired patients the combination may deteriorate renal function, including possible acute renal failure, and may weaken the blood pressure effect [1]. Aliskiren is contraindicated with losartan in diabetes and should be avoided when GFR is below 60 mL/min [1].

In VA NEPHRON-D, 1448 patients with type 2 diabetes on losartan were randomized to add lisinopril or placebo for a median of 2.2 years; the combination gave no additional benefit on GFR decline, end-stage renal disease or death, with more hyperkalemia and acute kidney injury [1].

Pregnancy and other label warnings

Losartan carries a boxed warning for fetal toxicity: when pregnancy is detected, discontinue as soon as possible. Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. The label also states that second and third trimester use reduces fetal renal function and increases fetal and neonatal morbidity and death [1]. Angioedema, including laryngeal swelling, is listed under postmarketing experience [1].