Calcium channel blockers are used to treat high blood pressure, angina (chest pain), and coronary artery disease. These medications work by relaxing the muscles of your heart and blood vessels, which helps to lower blood pressure and reduce chest pain. Calcium channel blockers come in different forms, including oral pills and liquids. Examples include amlodipine (Norvasc, Katerzia), diltiazem ER (Cardizem CD, Tiazac), and verapamil ER (Verelan).