Systemic: Losartan—Losartan is a nonpeptide angiotensin II receptor antagonist with high affinity and selectivity for the AT 1 receptor. Losartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by inhibiting the binding of angiotensin II to the AT 1 receptor. AT 1 receptor blockade results in an increase in plasma renin activity (PRA) followed by increases in plasma angiotensin II concentration. The potential clinical consequences of these increases are not clear. Angiotensin II agonist effects have not been demonstrated. Hydrochlorothiazide—Hydrochlorothiazide is a thiazide diuretic. Thiazide diuretics increase urinary excretion of sodium and water by inhibiting sodium reabsorption in the early distal tubule. The diuretic action of hydrochlorothiazide decreases plasma volume, resulting in increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. Since the renin-aldosterone link is mediated by angiotensin II, coadministration of losartan tends to reverse the potassium loss associated with hydrochlorothiazide.