Isosorbide nitrate extended-release tablets work to prevent coronary heart disease and angina pectoris; treat angina pectoris after myocardial infarction and chronic congestive heart failure. The main pharmacological effect of the drug is relaxation of vascular smooth muscle. Among other things, venous dilatation causes blood to be trapped in the periphery, the volume of returned blood is reduced, and left ventricular end-diastolic pressure and and pulmonary capillary wedge embedded pressure are reduced; arterial dilatation causes peripheral vascular resistance, systolic arterial pressure and mean arterial pressure to be reduced. The overall effect is a decrease in myocardial oxygen consumption, an increase in oxygen supply, and relief of angina. Therefore, the drug is clinically used for the prevention of coronary heart disease and angina pectoris; the treatment of angina pectoris after myocardial infarction and chronic congestive heart failure. Nitrate-induced vasodilatory headache may occur at the initial stage of drug use, and adverse reactions such as facial flushing, dizziness and postural hypotension may also occur. It is contraindicated in patients with acute circulatory failure, severe hypotension, severe anemia, glaucoma, and increased intracranial pressure. Acute myocardial infarction with low filling pressure, aortic or mitral stenosis, postural hypotension, renal insufficiency should be used with caution; pregnant and lactating women should be cautious. If medication is needed, it should be used under the guidance of a specialist.