ACE and Hypertension: Although there have been more than 69 drugs in 15 different classes of antihypertensive drugs, such as calcium antagonists, angiotensin-converting enzyme inhibitors, β-adrenoceptor antagonists, diuretics, and direct-acting vasodilators, many more hypertensive patients have resistant hypertension or are uncontrolled for nonadherence or intolerance to available antihypertensive agents (Oparil and Schmieder, 2015).