Nifedipine drug molecule, molecular model. Atoms are represented as rods and colour-coded; carbon (light blue), hydrogen (white), oxygen (red) and nitrogen (dark blue). Nifedipine belongs to a group of drugs, known as calcium-channel blockers, that are used to treat angina (chest pain) and hypertension (high blood pressure). These drugs work by blocking the movement of calcium into the smooth muscle cells lining coronary and peripheral arteries. Calcium is involved in muscle contraction, so blocking it causes muscles to relax and the arteries to dilate. This leads to lowered blood pressure and reduces the heart muscle's demand for oxygen.