What is Losartan used for?

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 the progression of diabetic nephropathy in type 2 diabetics with proteinuria. 1

Primary Indications

Hypertension (High Blood Pressure)

• Losartan is FDA-approved for treating hypertension in adults and children 6 years and older to lower blood pressure and reduce the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarction. 1
• Lowering blood pressure reduces cardiovascular risk across all populations, with the benefit being greater in patients at higher baseline risk (such as those with diabetes or hyperlipidemia). 1
• Losartan can be used alone or in combination with other antihypertensive agents, particularly thiazide diuretics like hydrochlorothiazide. 1, 2
• The typical starting dose is 50 mg once daily, with titration to 100 mg once daily as needed for blood pressure control. 3, 1

Stroke Prevention in Left Ventricular Hypertrophy

• Losartan is indicated to reduce stroke risk in hypertensive patients with left ventricular hypertrophy (LVH), an enlargement of the heart's main pumping chamber caused by chronic high blood pressure. 1
• In the LIFE study, losartan reduced cardiovascular endpoints by 24% and all-cause mortality by 39% compared to atenolol in diabetic patients with hypertension and LVH. 4, 5
• Important caveat: This stroke reduction benefit does not apply to Black patients based on clinical trial evidence. 1

Diabetic Nephropathy (Kidney Disease)

• Losartan is FDA-approved for treating diabetic nephropathy in type 2 diabetic patients with elevated serum creatinine and proteinuria (urinary albumin to creatinine ratio ≥300 mg/g) who have a history of hypertension. 1
• It slows the progression of kidney disease by reducing the rate of doubling of serum creatinine and the need for dialysis or renal transplantation. 1, 6
• The target dose for diabetic nephropathy is 100 mg once daily. 3
• Losartan provides renoprotective effects beyond simple blood pressure lowering through blockade of the renin-angiotensin system. 5, 6

Additional Clinical Uses (Based on Guidelines)

Gout Management

• For patients with gout who require diuretic therapy for hypertension, losartan is an attractive alternative antihypertensive because it has modest uricosuric effects (increases uric acid excretion). 4
• Diuretics are a common risk factor for gout, and switching to losartan may help lower both blood pressure and serum uric acid levels. 4

Heart Failure

• While not the primary indication in the FDA label, losartan at higher doses (150 mg daily) has been studied for heart failure with reduced ejection fraction, showing a 10% relative risk reduction in death or heart failure hospitalization compared to lower doses. 3
• The European Society of Cardiology recommends losartan 50 mg as the starting dose with 150 mg as the target dose for heart failure patients. 3

Mechanism of Action

• Losartan works by selectively blocking the angiotensin II type 1 (AT1) receptor, preventing angiotensin II from causing blood vessel constriction and other harmful cardiovascular effects. 7, 2
• It is converted by the liver to an active metabolite (E-3174) that is 10-40 times more potent than losartan itself and has a half-life of 6-9 hours, allowing once-daily dosing. 7

Important Safety Considerations

Pregnancy Warning

• Losartan can cause serious harm or death to an unborn baby when used during the second and third trimesters of pregnancy. 1
• Women who are pregnant or planning to become pregnant should discuss alternative blood pressure medications with their doctor immediately. 1

Monitoring Requirements

• Serum creatinine/eGFR and potassium should be checked within 1-2 weeks after starting losartan or increasing doses, then monitored at least annually. 3
• Blood pressure should be monitored regularly to assess treatment response. 5

Drug Interactions to Avoid

• Do not combine losartan with ACE inhibitors or direct renin inhibitors (aliskiren), as this increases the risk of hyperkalemia, syncope, and acute kidney injury without providing additional benefit. 3, 1
• Use caution with potassium supplements, salt substitutes containing potassium, and potassium-sparing diuretics due to hyperkalemia risk. 1

Common Pitfalls

• Underdosing is widespread in clinical practice, with less than 25% of patients titrated to target doses. 3
• For hypertension, the maximum recommended dose is 100 mg once daily; for heart failure and diabetic nephropathy, higher doses (up to 150 mg daily) may be beneficial. 3, 1
• Losartan can be taken with or without food, and no dosage adjustment is needed for elderly patients or those with mild-to-moderate renal impairment. 7