What is Losartan used for in adult patients, especially those with cardiovascular or kidney disease?

What is Losartan Used For?

Losartan is an angiotensin II receptor blocker (ARB) used primarily to treat hypertension, reduce stroke risk in hypertensive patients with left ventricular hypertrophy, and slow progression of diabetic nephropathy in type 2 diabetics with proteinuria. 1

Primary FDA-Approved Indications

Hypertension

• Losartan lowers blood pressure in adults and children ≥6 years of age, thereby reducing the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarction 1
• It is recommended as first-line therapy alongside ACE inhibitors, dihydropyridine calcium channel blockers, and thiazide diuretics for uncomplicated hypertension 2
• For patients with diabetes and albuminuria (ACR ≥30 mg/g), losartan is specifically recommended as first-line therapy at a goal dose of 50-100 mg daily 3

Stroke Prevention in Left Ventricular Hypertrophy

• Losartan reduces stroke risk by 24% in hypertensive patients with left ventricular hypertrophy, independent of blood pressure reduction alone 4
• Important caveat: This stroke reduction benefit does not apply to Black patients 1

Diabetic Nephropathy

• Losartan is indicated for type 2 diabetic patients with elevated serum creatinine and proteinuria (urinary albumin-to-creatinine ratio ≥300 mg/g) and a history of hypertension 1
• It reduces progression to end-stage renal disease by 28%, reduces doubling of serum creatinine, and decreases proteinuria by 20-35% within 3-6 months 3, 2
• The RENAAL trial demonstrated a 16% reduction in the composite endpoint of doubling serum creatinine, end-stage renal disease, or death (p=0.02) 5

Additional Clinical Applications Based on Guidelines

Chronic Kidney Disease with Albuminuria

• For CKD patients with severely increased albuminuria (with or without diabetes), losartan reduces risk of kidney failure and cardiovascular events 2
• Losartan should be titrated to the highest tolerated dose (up to 100 mg daily) for maximal renoprotective benefit 3
• The renoprotective effects occur through reduction of intraglomerular pressure and proteinuria, independent of blood pressure lowering 4

Heart Failure with Reduced Ejection Fraction

• Losartan is an alternative to ACE inhibitors in patients with acute myocardial infarction complicated by left ventricular systolic dysfunction (LVEF <40%) 6
• The VALIANT trial showed losartan was noninferior to captopril in post-MI patients with LV dysfunction 6
• Losartan prevents heart failure development in diabetic patients with additional cardiovascular risk factors 4

Post-Myocardial Infarction

• In hypertensive patients with MI and LV dysfunction, losartan should be prescribed at hospital discharge if ACE inhibitors are not tolerated 6
• The ELITE II trial found comparable rates of all-cause mortality and sudden death between losartan 50 mg/day and captopril 150 mg/day 6

Practical Dosing and Implementation

Starting and Target Doses

• Start at 25-50 mg daily and titrate to a goal dose of 50-100 mg daily 3
• For diabetic nephropathy specifically, the target is 50-100 mg daily 6, 3
• The commonly prescribed 50 mg daily dose may be suboptimal; 100 mg daily or higher provides greater benefit 6, 4
• The HEAAL trial demonstrated that losartan 150 mg daily was superior to 50 mg daily, with a 10% relative risk reduction in death or heart failure hospitalization 4

Monitoring Requirements

• Check serum creatinine and potassium within 2-4 weeks after initiation or dose increase 2, 4
• A modest creatinine rise of 10-20% is expected and hemodynamic, not indicative of kidney injury 3
• Continue therapy if creatinine rises <30% from baseline 3
• Halve the dose if potassium rises to >5.5 mmol/L; stop immediately if potassium ≥6.0 mmol/L 2

Combination Therapy

• Losartan may be combined with hydrochlorothiazide for enhanced blood pressure control and proteinuria reduction 1, 7
• Never combine losartan with ACE inhibitors or direct renin inhibitors—this increases adverse effects (hyperkalemia, acute kidney injury, hypotension) without additional cardiovascular or renal benefit 3, 2, 4

Critical Caveats and Pitfalls

Contraindications and Precautions

• Avoid in pregnancy (second and third trimester)—associated with serious fetal toxicity 8
• Contraindicated in severe renal failure (CrCl <30 mL/min) according to some guidelines, though fondaparinux data suggest potential use with careful monitoring 6
• Use caution in bilateral renal artery stenosis due to risk of acute renal failure 2

Drug Interactions

• Avoid combining with potassium-sparing diuretics (e.g., spironolactone) due to compounded hyperkalemia risk, especially in CKD or diabetes 2
• Losartan has a favorable drug interaction profile with no clinically relevant interactions with warfarin, digoxin, or hydrochlorothiazide 8

Special Populations

• No dosage adjustment needed for age, sex, race, or mild hepatic impairment 8
• Start at lower doses in patients with GFR <45 mL/min/1.73 m² 2
• Temporarily suspend during interval illness, IV radiocontrast administration, bowel preparation, or prior to major surgery 2

Common Misunderstandings

• Do not discontinue losartan for an expected modest creatinine rise (10-20%)—this deprives patients of long-term renoprotective benefits 3
• The dose for hypertension (25-50 mg) is lower than optimal doses for heart failure or diabetic nephropathy (100-150 mg) 6
• Losartan is not removed by hemodialysis 8