Metoprolol Tartrate Tablet

Name: Metoprolol Tartrate Tablet

Metoprolol Tartrate Tablet Description

Metoprolol tartrate, USP is a selective beta1-adrenoreceptor blocking agent, available as 25 mg, 50 mg and 100 mg tablets for oral administration. Metoprolol tartrate USP is (±)-1-(Isopropylamino)-3-[p-2-methoxyethyl)phenoxy]-2-propanol L-(+)-tartrate (2:1) salt, its structural formula is:

Metoprolol tartrate USP is a white, practically odorless, crystalline powder with a molecular weight of 684.82. It is very soluble in water; freely soluble in methylene chloride, in chloroform, and in alcohol; slightly soluble in acetone; and insoluble in ether.

Each tablet for oral administration contains 25 mg, 50 mg or 100 mg of metoprolol tartrate and the following inactive ingredients: microcrystalline cellulose, lactose monohydrate, povidone, croscarmellose sodium, colloidal silicon dioxide, magnesium stearate hypromellose, titanium dioxide and macrogol. In addition, the 50 mg product contains D&C Red No. 30 Aluminum Lake and the 100 mg product contains FD&C Blue No. 2 Aluminum Lake and FD&C Blue No. 1 Aluminum Lake as coloring agents.

Indications & usage

Hypertension
Metoprolol Tartrate Tablets are indicated for the treatment of hypertension. They may be used alone or in combination with other antihypertensive agents.
Angina Pectoris
Metoprolol Tartrate Tablets are indicated in the long-term treatment of angina pectoris.
Myocardial Infarction

Metoprolol Tartrate Tablets are indicated in the treatment of hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality when used alone or in conjunction with intravenous metoprolol. Oral metoprolol therapy can be initiated after intravenous metoprolol therapy or, alternatively, oral treatment can begin within 3 to 10 days of the acute event (see DOSAGE AND ADMINISTRATION, CONTRAINDICATIONS, and WARNINGS).

Contraindications

Hypertension and Angina
Metoprolol Tartrate Tablets are contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure (see WARNINGS).
Hypersensitivity to metoprolol and related derivatives, or to any of the excipients; hypersensitivity to other beta-blockers (crosssensitivity between beta-blockers can occur).
      Sick-sinus syndrome.
      Severe peripheral arterial circulatory disorders.

Myocardial Infarction
Metoprolol is contraindicated in patients with a heart rate < 45 beats/min; second- and third-degree heart block; significant first-degree heart block (P-R interval ≥ 0.24 sec); systolic blood pressure < 100 mmHg; or moderate to severe cardiac failure (see WARNINGS).

Warnings

Heart Failure
Beta blockers, like metoprolol, can cause depression of myocardial contractility and may precipitate heart failure and cardiogenic shock. If signs or symptoms of heart failure develop, treat the patient according to recommended guidelines. It may be necessary to lower the dose of metoprolol or to discontinue it.
 

Ischemic Heart Disease
Do not abruptly discontinue metoprolol therapy in patients with coronary artery disease. Severe exacerbation of angina, myocardial infarction and ventricular arrhythmias have been reported in patients with coronary artery disease following the abrupt discontinuation of therapy with beta-blockers.
When discontinuing chronically administered metoprolol, particularly in patients with coronary artery disease, the dosage should be gradually reduced over a period of 1 to 2 weeks and the patient should be carefully monitored. If angina markedly worsens or acute coronary insufficiency develops, metoprolol administration should be reinstated promptly, at least temporarily, and other measures appropriate for the management of unstable angina should be taken. Patients should be warned against interruption or discontinuation of therapy without the physicians advice.
Because coronary artery disease is common and may be unrecognized, it may be prudent not to discontinue metoprolol therapy abruptly even in patients treated only for hypertension.
 
Use During Major Surgery
Chronically administered beta-blocking therapy should not be routinely withdrawn prior to major surgery; however, the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures.
 
Bradycardia
Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction, or conduction disorders may be at increased risk. Monitor heart rate and rhythm in patients receiving metoprolol. If severe bradycardia develops, reduce or stop metoprolol.
 
Exacerbation of Bronchospastic Diseases
Patients with bronchospastic diseases, should, in general, not receive beta blockers, including metoprolol. Because of its relative beta1 selectivity, however, metoprolol may be used in patients with bronchospastic disease who do not respond to, or cannot tolerate, other antihypertensive treatment. Because beta1 selectivity is not absolute use, the lowest possible dose of metoprolol tartrate and consider administering metoprolol in smaller doses three times daily, instead of larger doses two times daily, to avoid the higher plasma levels associated with the longer dosing interval (see DOSAGE AND ADMINISTRATION). Bronchodilators, including beta2 agonists, should be readily available or administered concomitantly.

Diabetes and Hypoglycemia
Beta-blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected.

Pheochromocytoma 
If metoprolol is used in the setting of pheochromocytoma, it should be given in combination with an alpha-blocker, and only after the alpha-blocker has been initiated. Administration of beta-blockers alone in the setting of pheochromocytoma has been associated with a paradoxical increase in blood pressure due to the attenuation of beta-mediated vasodilatation in skeletal muscle.

Thyrotoxicosis
Metoprolol Tartrate Tablets may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Avoid abrupt withdrawal of beta-blockade, which might precipitate a thyroid storm.

Overdosage

Acute Toxicity

Several cases of overdosage have been reported, some leading to death.

Oral LD50’s (mg/kg): mice, 1,158 - 2,460; rats, 3,090 - 4,670.

Signs and Symptoms

Potential signs and symptoms associated with overdosage with metoprolol are bradycardia, hypotension, bronchospasm, myocardial infarction, cardiac failure and death.

Management

There is no specific antidote.

In general, patients with acute or recent myocardial infarction may be more hemodynamically unstable than other patients and should be treated accordingly (see WARNINGS: Myocardial Infarction).

On the basis of the pharmacologic actions of metoprolol, the following general measures should be employed:

Elimination of the Drug: Gastric lavage should be performed.

Other clinical manifestations of overdose should be managed symptomatically based on modern methods of intensive care.

Hypotension: Administer a vasopressor, e.g.,levarterenol or dopamine.

Bronchospasm: Administer a beta2-stimulating agent and/or a theophylline derivative.

 Cardiac Failure:

Administer digitalis glycoside and diuretic. In shock resulting from inadequate cardiac contractility, consider administration of dobutamine, isoproterenol or glucagon.

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