It is a beta-blocker that reduces myocardial contractility, autoregulation, conduction and excitability, slows heart rate, and reduces cardiac output and myocardial oxygen consumption. It is used for atrial and ventricular premature beats, sinus and supraventricular tachycardia, angina pectoris, acute infarction, hypertension, etc. In chronic atrial fibrillation and flutter, if digitalis is not effective, the addition of this product can often slow down the ventricular rate. For the treatment of: ① arrhythmias, correction of supraventricular tachyarrhythmias, ventricular arrhythmias, panditoxin and catecholamine-induced tachyarrhythmias; ② angina pectoris (typical angina pectoris, i.e., exertional angina); ③ hypertension, as a first-line drug, alone or in combination with other drugs; ④ hypertrophic cardiomyopathy, for reducing the outflow tract pressure difference and alleviating symptoms such as angina pectoris, palpitations and syncope; ⑤ Pheochromocytoma, to control tachycardia; ⑥ Hyperthyroidism, to control tachycardia, and also to treat thyroid crisis or precipitant crisis; preoperative preparation for subtotal thyroidectomy; to control symptoms in patients with severe hyperthyroidism before anti-thyroid drugs or radioactive iodine therapy are effective. (7) Myocardial infarction; as secondary prevention; (8) Mitral valve prolapse syndrome. (1) This product can enter the fetus through the placenta. It has been reported that the use of this product in pregnant hypertensive patients can cause intrauterine fetal growth retardation and obstructed labor due to weakness during delivery, and the newborn can produce hypotension, hypoglycemia, respiratory depression and slowed heart rate. (2) It can be secreted in small amounts from breast milk, so the advantages and disadvantages must be weighed against its use in lactating women. (3) The elderly have low metabolism and excretion capacity of this product, so the dose should be adjusted appropriately. (4) The following conditions should be prohibited: (1) bronchial asthma; (2) cardiogenic shock; (3) cardiac conduction block (degree II to III AV block); (4) severe heart failure; (5) sinus bradycardia. (5) The following conditions should be used with caution: (1) history of allergy; (2) congestive heart failure; (3) diabetes mellitus; (4) emphysema or non-allergic bronchitis; (5) hepatic insufficiency; (6) hypothyroidism; (7) Raynaud’s syndrome or other peripheral vascular disease; (8) renal hypofunction.