losartan

Losartan is an oral medication in the angiotensin II receptor blocker (ARB) class. It is used to treat hypertension, reduce the risk of stroke in adults with hypertension and left ventricular hypertrophy, and protect kidney function in adults with type 2 diabetes and albuminuria. It may also be used as part of kidney-protective therapy in certain patients with high blood pressure.

Mechanism of action: Losartan selectively blocks the angiotensin II type 1 (AT1) receptor, preventing angiotensin II from causing vasoconstriction and aldosterone release. This leads to vasodilation, reduced blood pressure, and decreased fluid retention.

Pharmacokinetics: Losartan is a prodrug that is rapidly absorbed and converted to its active metabolite EXP3174, which accounts for much of the antihypertensive effect. The parent drug and its metabolite are eliminated primarily by the liver and kidneys.

Administration and dosing: It is administered by mouth and is usually given once daily, with the dose adjusted by a clinician to achieve blood pressure targets or kidney protection. Availability includes generic formulations and brand names such as Cozaar.

Safety and precautions: Losartan is contraindicated during pregnancy and should be discontinued if pregnancy occurs. Cautions include bilateral renal artery stenosis, hyperkalemia, and reduced kidney function. Interactions with NSAIDs, potassium-sparing diuretics, and other drugs affecting the renin–angiotensin system can increase risk of kidney impairment or hyperkalemia.

Adverse effects: Common side effects include dizziness, fatigue, upper respiratory infections, and back pain. Hyperkalemia can occur, and very rarely angioedema may develop.

History: Losartan was approved for medical use in 1995. It was developed by Merck and is marketed under the brand name Cozaar, among others.