ACE and Hypertension: The classes of drugs most often used to treat hypertension include the thiazide diuretics, b-blockers, angiotensin-converting enzyme (ECA) inhibitors, angiotensin II receptors antagonists, calcium channel blockers, a-adrenoceptor blockers, combined a- and b-blockers, direct vasodilators, and some centrally acting drugs such as a2-adrenoceptor agonists (Dphil, 2004).