The main ingredient of Metoprolol Succinate Extended-Release Tablets is Metoprolol Succinate, which is often clinically indicated for patients with chronic heart failure with stable symptoms. Metoprolol succinate is a selective β1 receptor blocker, acting on the β1 receptor of the heart, attenuating the effects of catecholamines related to physiological and psychological load, reducing heart rate, cardiac output and blood pressure, clinically, it is mainly applied to patients with symptomatic stabilized chronic heart failure who suffer from hypertension, angina pectoris, and accompanied by abnormalities of left ventricular systolic function. It should be noted that this product may cause blood and lymphatic system diseases, thrombocytopenia, psychosis and other adverse reactions, and related to the dose, need to be used under the guidance of a doctor, cardiogenic shock, sick sinus node syndrome, Ⅲ degree atrioventricular block, unstable, uncompensated heart failure patients, patients with severe peripheral vascular disease associated with the risk of gangrene is prohibited. Drugs should be used in accordance with medical advice.