Losartan/Hydrochlorothiazide

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A combination preparation of a synthetic angiotensin II antagonist and a diuretic thiazide, with antihypertensive activity. Losartan, and its metabolite, selectively and competitively block the binding of angiotensin II to the angiotensin II (AT1) receptor. As a result, angiotensin II-AT1 mediated physiological effects such as vasoconstriction and stimulation of aldosterone synthesis and secretion, which regulates extracellular sodium concentration, are blocked. Hydrochlorothiazide inhibits electrolytes reabsorption via binding to Na-Cl cotransporter on the renal distal tubular, thereby increasing excretion of sodium, potassium, chloride, bicarbonate and water. Both agents lead to a reduction in blood pressure.

**Synonyms:** - Hyzaar - Losartan Potassium/Hydrochlorothiazide