Author: Su Qunfang
Betalox Betalac is the trade name of metoprolol, and there are two common drugs, one is metoprolol tartrate tablets (25mg, 50mg, 100mg) and the other is metoprolol succinate extended-release tablets (47.5mg, 95mg), their main ingredient is metoprolol, both belong to the highly selective beta1 blocker.
Blockers block cardiac adrenergic receptor synthesis, reduce myocardial contractility, slow heart rate, lower blood pressure, and thereby reduce myocardial oxygen consumption. In addition, by prolonging the diastolic period and increasing coronary collateral perfusion, the scope of infarction can be narrowed and the incidence of cardiovascular adverse events such as sudden death can be reduced. Long-term use of β receptor blockers improves long-term prognosis and survival in patients with myocardial infarction. According to the relative selectivity of β receptors, the efficacy of the two is basically the same, but there is still a certain difference.
The difference between metoprolol succinate tablets and metoprolol succinate extended-release tablets
In the table above, the doses of 50 mg of metoprolol tartrate tablets and 47.5 mg of metoprolol succinate extended-release tablets are comparable.
Release speed
Metoprolol tartrate tablets are ordinary tablets, bioavailability is 40 to 50%, 1 to 2 hours after taking the drug to achieve maximum effect, rapid absorption, rapid onset of action, suitable for patients who need rapid control of heart rate, such as frequent attacks of angina.
Metoprolol succinate extended-release tablets are extended-release preparations, bioavailability is 30 to 40%, the drug is slowly released after taking the drug, the action time is long, and it is suitable for the maintenance treatment of chronic diseases such as long-term medication for coronary heart disease.
Adverse reactions
In terms of adverse reactions, the two are basically the same. As a lipophilic beta1 receptor blocker, betalek can penetrate the blood-brain barrier and may cause adverse reactions such as headache, dizziness, and insomnia. But also there will be fatigue, acral chills, bradycardia, palpitations, abdominal pain, nausea, vomiting, diarrhea and other symptoms, long-term use of betalek, especially friends with renal insufficiency, must pay attention to regular monitoring of blood potassium levels, to avoid the occurrence of hyperkalemia problems, long-term eat betalek, blood glucose, blood lipid metabolism, may also be affected, therefore, in the process of long-term medication, but also to more actively strengthen the control of blood glucose and lipids. However, due to the slower drug release rate of metoprolol succinate extended-release tablets, the adverse reactions are relatively mild.
Precautions
1, the application of betalek, the first thing that should be noted is to do a good job of heart rate monitoring, such drugs have the effect of strengthening heart rate control, heart rate too fast will affect health, but the heart rate is too slow, it is not OK, low heart rate to maintain above 55.
2. Do not stop the drug suddenly, otherwise there will be a withdrawal reaction. Long-term use of betalec can upregulate the expression of β-receptors. If abruptly discontinued, patients with ischemic heart disease can induce angina attacks and even myocardial infarction because a large number of β-receptors can be utilized by catecholamines, which promotes heart and blood vessel contraction and forms a blood pressure rebound. Therefore, this product should be withdrawn as gradually as possible, and when it is necessary to stop the drug, it is necessary to go through a process of gradual reduction and discontinuation of the drug for about 2 weeks.
bibliography:
[1] BhattAS,etal. Journal of the American College of Cardiology201769(20):2542-2550.
Cardiovascular Diseases Branch of Chinese Medical Association. Chinese Journal of Cardiovascular Diseases, 2014, 42(2): 3-10
[3] 2010 China "Expert Consensus on the Application of β Adrenergic Blockers in Cardiovascular Diseases"