The generic name of Betalucil is metoprolol. The duration of the drug effect of metoprolol regular tablets is 4 to 6 hours with a half-life of 3 to 5 hours, while the duration of the drug effect of metoprolol extended-release tablets is longer, up to 24 hours, with a half-life of about 20 hours. For ordinary metoprolol tablets, due to the short half-life and shorter duration of drug effect, it is usually necessary to take the drug 2 to 3 times a day in order to achieve the ideal heart rate and blood pressure, and the fluctuation of blood concentration is also larger, which is not conducive to the smoothness of heart rate and blood pressure. On the other hand, metoprolol extended-release tablets have a long half-life and need to be taken only once a day, which makes it easy for patients to use and the adherence to medication is higher. Moreover, the slow release of the drug in the body can maintain a more stable blood concentration, and the stability of heart rate and blood pressure will be higher. The main adverse effects of metoprolol are fatigue, headache, dizziness, bradycardia, palpitations, abdominal pain, nausea, vomiting, diarrhea and constipation. Chest pain, weight gain, sleep disturbances, sensory abnormalities, and shortness of breath and dyspnea may also occur. Metoprolol is contraindicated in patients who are allergic to the components of the drug, cardiogenic shock, sick sinus node syndrome, atrioventricular block of the 2nd, 3rd degree. When using metoprolol for the treatment of arrhythmia and hypertension, it is important to apply it under the guidance of a specialist, as well as to monitor blood pressure, adjust the dose of the drug in a timely manner according to the level of blood pressure, and consult a doctor in case of adverse reactions.