Betalock, also known as metoprolol tablets, is divided into two types, one is metoprolol tartrate tablets, administered 2-3 times a day, should be taken on an empty stomach, because taking the drug with a meal can increase the bioavailability of the drug by 40%; the other is metoprolol succinate sustained-release tablets, administered once a day, preferably in the morning, which can be broken, but cannot be chewed or crushed, and eating does not affect its bioavailability. Metoprolol is a beta-blocker and is used clinically for the treatment of hypertension, angina, and heart failure. Adverse effects are usually dose-related and may include fatigue, dizziness, headache, coldness in the extremities, bradycardia, palpitations, and other discomforts. It is contraindicated in patients with cardiogenic shock, sick sinus node syndrome, high degree of atrioventricular block, and decompensated heart failure. In order to avoid the occurrence of bradycardia, the dosage of Metoprolol should be individualized, and the medication and dosage adjustment should be made under the guidance of professional physicians in regular hospitals.