What it's for (Indications)
- Metoprolol tartrate is a selective beta-1 blocker used in adults as an immediate-release formulation.
- It is indicated for the treatment of hypertension, angina pectoris, and for the treatment of acute myocardial infarction, typically initiated 3 to 10 days post-event to reduce the risk of further cardiovascular events and mortality, especially in patients with coronary artery disease.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | The dosage of metoprolol tartrate tablets should be individualized. As an immediate-release formulation, it typically requires administration several times per day. Tablets should be taken with or immediately following meals. For hypertension, the usual initial dosage is 100 mg daily, given in single or divided doses, either alone or when added to a diuretic. The dosage may be increased at weekly (or longer) intervals until optimal blood pressure reduction is achieved, with the maximum effect of any given dosage level generally apparent after 1 week. The effective dosage range is 100 to 450 mg per day; dosages exceeding 450 mg per day have not been studied. While once-daily dosing can be effective, lower doses (especially 100 mg) may not maintain a full effect throughout the 24-hour period, and larger or more frequent daily doses may be required, which should be evaluated by measuring blood pressure near the end of the dosing interval. For acute myocardial infarction, immediate-release metoprolol tartrate is typically administered several times daily, usually initiated 3 to 10 days after the event. |
Safety & Warnings
Common Side Effects
- Most adverse effects have been mild and transient.
- Common side effects include tiredness, fatigue, and dizziness (occurring in about 10% of patients), and depression (in about 5%).
- Other reported effects include mental confusion, short-term memory loss, headache, nightmares, and insomnia.
- Cardiovascular effects may include shortness of breath (dyspnea) and bradycardia (in approximately 3% of patients), cold extremities, arterial insufficiency (usually of the Raynaud type), palpitations, congestive heart failure, peripheral edema, and hypotension (in about 1%).
- Rarely, gangrene has been reported in patients with pre-existing severe peripheral circulatory disorders.
- Respiratory effects can include wheezing (bronchospasm) and rhinitis.
- Gastrointestinal disturbances include diarrhea, nausea, vomiting, and dry mouth.
Serious Warnings
- Black Box Warning: A boxed warning exists regarding ischemic heart disease. Abrupt cessation of therapy with beta-blocking agents, including metoprolol, has been associated with exacerbations of angina pectoris and, in some cases, myocardial infarction. When discontinuing chronically administered metoprolol, particularly in patients with ischemic heart 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 promptly reinstituted.
- Metoprolol tartrate should not be discontinued abruptly.
- Abrupt discontinuation may lead to exacerbations of angina pectoris, myocardial infarction, and abnormal heart rhythms, particularly in patients with ischemic heart 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 promptly reinstituted.
- Caution should be exercised in patients with respiratory conditions (due to potential for bronchospasm) and peripheral circulatory disorders.
How it Works (Mechanism of Action)
Metoprolol Tartrate is a beta-1 selective (cardioselective) adrenergic receptor blocker. This preferential effect is not absolute, and at higher plasma concentrations, Metoprolol Tartrate also inhibits beta-2 adrenoreceptors, chiefly located in the bronchial and vascular musculature. Its beta-blocking activity is demonstrated by (1) reduction in heart rate and cardiac output at rest and upon exercise, (2) reduction of systolic blood pressure upon exercise, (3) inhibition of isoproterenol-induced tachycardia, and (4) reduction of reflex orthostatic tachycardia. The mechanism of the antihypertensive effects of beta-blocking agents has not been fully elucidated, but proposed mechanisms include competitive antagonism of catecholamines at peripheral adrenergic neuron sites, leading to decreased cardiac output, and a central effect.