Dynacirc CR is part of the Calcium Channel Blockers class and treats Hypertension and Raynaud's Phenomenon. Calcium channel blockers are used to lower blood pressure to treat hypertension, PSVT, coronary artery disease, angina, and atrial fibrillation. They work by relaxing blood vessels allowing blood to flow easier to different parts of the body. Dynacirc CR is only available as a brand name drug.