Pharmacologyolmesartan: blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin ii. amlodipine: directly acts on vascular smooth muscle to produce peripheral arterial vasodilation reducing peripheral vascular resistance and blood pressure. hydrochlorothiazide: inhibits sodium reabsorption in the distal tubules causing increased excretion of sodium and water as well as potassium and hydrogen ions.