Amlodipine relaxes the blood vessels and increases the supply of blood and oxygen to the heart while reducing its workload. Valsartan is an angiotensin II receptor blocker (ARB). It works by blocking a substance in the body that causes blood vessels to tighten. Hydrochlorothiazide directly inhibits the sodium chloride cotransporter located on the apical membrane of the distal convoluted tubules in the kidney. The distal convoluted tubule is responsible for reabsorbing approximately 5% to 10% of the sodium in the kidney.