Losartan Potassium

What it is and how it works

Mechanism of Action Angiotensin II [formed from angiotensin I in a reaction catalyzed by angiotensin converting enzyme (ACE, kininase II)] is a potent vasoconstrictor, the primary vasoactive hormone of the renin-angiotensin system, and an important component in the pathophysiology of hypertension. It also stimulates aldosterone secretion by the adrenal cortex. Losartan and its principal active metabolite block the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT 1 receptor found in many tissues, (e.g., vascular smooth muscle, adrenal gland).

Indications

Losartan potassium tablet is an angiotensin II receptor blocker (ARB) indicated for: • Treatment of hypertension, to lower blood pressure in adults and children greater than 6 years old. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. • Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy. There is evidence that this benefit does not apply to Black patients. • Treatment of diabetic nephropathy with an elevated serum creatinine and proteinuria in patients with type 2 diabetes and a history of hypertension. Hypertension Losartan potassium tablets are indicated for the treatment of hypertension in adults and pediatric patients 6 years of age and older, to lower blood pressure. Lowering blood pressure lowers the risk of fatal and nonfatal cardiovascular (CV) events, primarily strokes and myocardial infarction. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including losartan.

Dosage and administration (summary)

Hypertension • Usual adult dose: 50 mg once daily. • Usual pediatric starting dose: 0.7 mg per kg once daily (up to 50 mg). Hypertensive Patients with Left Ventricular Hypertrophy • Usual starting dose: 50 mg once daily. • Add hydrochlorothiazide 12.5 mg and/or increase losartan potassium to 100 mg followed by an increase to hydrochlorothiazide 25 mg if further blood pressure response is needed. ( 2.2, 14.2 ) Nephropathy in Type 2 Diabetic Patients • Usual dose: 50 mg once daily. • Increase dose to 100 mg once daily if further blood pressure response is needed. Hypertension Adult Hypertension The usual starting dose of losartan potassium tablets is 50 mg once daily.

Contraindications

Losartan potassium is contraindicated: • In patients who are hypersensitive to any component of this product. • For coadministration with aliskiren in patients with diabetes. • Hypersensitivity to any component. • Coadministration with aliskiren in patients with diabetes.

Warnings and precautions

• Hypotension: Correct volume or salt depletion prior to administration of losartan potassium. • Monitor renal function and potassium in susceptible patients. ( 5.3 , 5.4 ) Fetal Toxicity Losartan potassium can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin-‑angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations.

Pregnancy

Pregnancy Risk Summary Losartan potassium can cause fetal harm when administered to a pregnant woman. Use of drugs that act on the renin‑-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death.

Storage and supply

Losartan potassium tablets, USP are supplied as follows: • Losartan potassium tablets, USP, 25 mg, are white, oval shaped, biconvex, film-coated tablets, debossed with “ML” on one side and “14” on other side. Bottles of 30, NDC 68788-4091-3 Bottles of 90, NDC 68788-4091-9 Bottles of 1000, NDC 72205-143-99 Store at 25°C (77°F).

Source: Losartan Potassium (Losartan Potassium) — US FDA prescribing information, 2026-03-17, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.