Product Overview
[Drug Name]
Generic Name: Metoprolol Succinate Sustained-Release Tablets
Trade Name: Betaloc
English Name: Metoprolol Succinate Sustained-Release Tablets
Chinese Pinyin: Huposuan meituoluo'er huanshipian
[Ingredients]
The main ingredient of this product is metoprolol succinate.
[Appearance]
This product is a white or off-white film-coated tablet. It appears white after removal of the coating.
[Indications]
This product is indicated for hypertension, angina pectoris, and stable chronic heart failure with symptoms of left ventricular systolic dysfunction.
[Dosage and Administration]
Oral administration, once daily, preferably in the morning. The tablet may be broken but not chewed or crushed. It should be taken with at least half a cup of liquid. Concomitant consumption of food does not affect its bioavailability.
The dosage should be individualized to avoid bradycardia.
The following are effective dosing guidelines:
1. Hypertension: 47.5-95 mg once daily. Patients who do not respond to 95 mg can be treated with other antihypertensive medications, preferably diuretics and dihydropyridine calcium channel blockers, or the dose can be increased.
2. Angina: 95-190 mg once daily. Nitrates can be used or the dose increased as needed. In patients with stable heart failure, treatment with an angiotensin-converting enzyme inhibitor, a diuretic, and possibly a digitalis is recommended. Patients should have stable chronic heart failure, have not experienced acute heart failure in the past six weeks, and have not had their basic therapy changed in the past two weeks.
Treatment of heart failure with beta-blockers can sometimes cause a temporary worsening of symptoms. In some cases, treatment can be continued or reduced, while in others, discontinuation may be necessary. For patients with severe heart failure (NYHA IV), initiation of treatment with metoprolol succinate extended-release tablets should only be determined by physicians specifically trained in the treatment of heart failure. 3. Dosing for Patients with Class II Stable Heart Failure: The recommended starting dose for the first two weeks of treatment is 23.75 mg once daily. After two weeks, the dose can be increased to 47.5 mg once daily. Thereafter, the dose can be doubled every two weeks. The target dose for long-term treatment is 190 mg once daily.
4. Dosing for Patients with Class III-IV Stable Heart Failure: The recommended starting dose is 11.875 mg (half a 23.75 mg tablet) once daily. The dose should be individualized, and patients should be closely monitored during dose increases, as heart failure symptoms may worsen in some patients. After one to two weeks, the dose can be increased to 23.75 mg once daily. After an additional two weeks, the dose can be increased to 47.5 mg once daily. For patients who can tolerate higher doses, the dose can be doubled every two weeks to a maximum of 190 mg once daily. Patients with hypotension and/or bradycardia may need to have their concomitant medications or the dose of this medication reduced. Initial hypotension does not necessarily mean that the patient will not tolerate this medication in the long term, but the dose should be increased only after the patient's condition stabilizes. Other precautions include the need for increased renal function monitoring.
5. Renal Impairment: Renal function has no significant effect on clearance, so no dose adjustment is required in patients with renal impairment.
6. Hepatic Impairment: The dose of metoprolol succinate in patients with cirrhosis is generally the same as that in patients with normal hepatic function. Dose reduction should only be considered in patients with very severe hepatic impairment (such as those undergoing bypass surgery).
[Adverse Reactions]
Adverse reactions occur in approximately 10% of patients and are generally dose-related. Rare cases of arthralgia, hepatitis, painful muscle cramps, dry mouth, conjunctivitis-like symptoms, rhinitis, impaired concentration, and, in patients with concomitant vascular disease, gangrene have been reported.
[Contraindications]
Cardiogenic shock. Sick sinus syndrome. Second- and third-degree atrioventricular block. Patients with unstable, decompensated heart failure (pulmonary edema, hypoperfusion, or hypotension), patients receiving continuous or intermittent inotropic therapy with beta-agonists, symptomatic bradycardia or hypotension. This drug should not be administered to patients with suspected acute myocardial infarction and a heart rate of 0.24 seconds or a systolic blood pressure <100 mmHg. Patients with heart failure indications whose supine systolic blood pressure is consistently below 100 mmHg should have their suitability for this drug reassessed before initiating treatment. Patients with severe peripheral vascular disease who are at risk of gangrene. Patients with hypersensitivity to any component of this drug or other beta-blockers.
[Precautions]
Metoprolol may exacerbate symptoms of peripheral circulatory disorders, such as intermittent claudication. Caution is advised in patients with severe renal impairment, acute conditions associated with metabolic acidosis, and when used concomitantly with digitalis. Patients with Prinzmetal's angina may experience increased frequency and severity of angina attacks after taking beta-blockers due to alpha-receptor-mediated coronary vasoconstriction. Therefore, non-selective beta-blockers should not be used in such patients. Selective beta-1 blockers should also be used with caution. Patients with bronchial asthma or other chronic obstructive pulmonary disease should also receive adequate bronchodilator therapy, and the dose of beta-2 agonists may need to be increased. Metoprolol therapy has a lower impact on glucose metabolism or the risk of masking hypoglycemia than non-selective beta-blockers. In rare cases, pre-existing moderate atrioventricular conduction abnormalities may worsen (possibly leading to atrioventricular block). Beta-blocker therapy may interfere with the treatment of allergic reactions, and conventional doses of epinephrine do not always yield the desired effect. Patients with pheochromocytoma who are taking metoprolol succinate should consider concomitant use of an alpha-blocker. Limited controlled clinical trial data exist on the efficacy and safety of tadalafil in patients with severe, symptomatic, stable heart failure (NYHA IV heart function). Therefore, treatment of such patients should be initiated only by experienced and well-trained physicians. Clinical studies in heart failure typically exclude patients with symptomatic heart failure who present with acute myocardial infarction and unstable angina. Therefore, data on the efficacy and safety of tadalafil in the treatment of patients with concurrent acute myocardial infarction and heart failure are lacking. This drug is contraindicated in patients with unstable, decompensated heart failure. Abrupt withdrawal of beta-blockers is dangerous, particularly in high-risk patients, and may worsen chronic heart failure and increase the risk of myocardial infarction and sudden death. Therefore, tadalafil should be withdrawn gradually, over at least two weeks, with the dose reduced by half each time until the final dose is half a 23.75 mg tablet. The last dose should be given at least four days prior to discontinuation. If symptoms develop, a slower withdrawal is recommended. If tadalafil is to be discontinued before surgery, it must be discontinued at least 48 hours in advance, except in special circumstances such as thyrotoxicosis and pheochromocytoma. Use with caution in athletes. Effects on driving and operating machinery. Dizziness and fatigue may occur during treatment with this drug. Therefore, caution should be exercised when using this drug during activities requiring concentration, such as driving or operating machinery.
[Special Populations]
Precautions in Children: Not yet available.
Precautions during Pregnancy and Lactation: Not yet available.
Precautions in the Elderly: Not yet available.
[Drug Interactions]
This drug should be avoided with the following medications: Barbiturates: Barbiturates (nembutal has been studied) can increase the metabolism of metoprolol through enzyme induction. Propafenone: In four patients already taking metoprolol, plasma concentrations of metoprolol increased 2- to 5-fold after administration of propafenone, with two of these patients experiencing metoprolol-related side effects. This interaction was confirmed in eight healthy volunteers. A possible explanation for this interaction is that propafenone, similar to quinidine, inhibits metoprolol metabolism through the cytochrome P4502D6 pathway. Because propranolol also has a β-receptor blocking effect, its combined use with metoprolol is difficult to master. Verapamil: When verapamil is used in combination with β-receptor blockers (already used with atenolol, propranolol, etc.), it is difficult to control its combined use with metoprolol. [Pharmacological Action] Pharmacological Action: This drug belongs to Class 2A, i.e., a β1-receptor blocker without partial agonist activity (cardioselective β-receptor blocker). It has a selective blocking effect on β1-receptors, lacks PAA (partial agonist activity), and has no membrane stabilizing effect. Its β-receptor blocking effect is approximately equal to that of propranolol (PP), and its selectivity for β1-receptors is slightly lower than that of atenolol. Metoprolol's effects on the heart include slowing the heart rate, inhibiting cardiac contractility, and reducing automaticity. Its effects on vasoconstriction and delay of atrioventricular conduction time are similar to those of propranolol and atenolol (AT). Its effect on reducing elevated blood pressure and heart rate during exercise testing is also similar to that of PP and AT. Its contraction of vascular and bronchial smooth muscle is weaker than that of PP, resulting in a lesser effect on the respiratory tract, but still more potent than that of AT.
[Storage] Store in a sealed container away from light.
[Specification] 47.5mg x 7s
[Expiry Date] 36 months
[Approval Number] National Medicine Standard No. J20150044
[Manufacturer] Company Name: AstraZeneca AB
