Metoprolol is a beta1-selective (cardioselective) adrenergic receptor blocking agent. This preferential effect is not absolute, however, and at higher plasma concentrations, metoprolol also inhibits beta2-adrenoreceptors, chiefly located in the bronchial and vascular musculature.

Metoprolol tartrate injection is used in hemodynamically stable patients with suspected or confirmed acute myocardial infarction (AMI). It is administered to reduce cardiovascular mortality, particularly when followed by oral metoprolol therapy.

Initial IV Therapy: Three 5 mg bolus injections given at 2-minute intervals.

Transition: Follow with oral metoprolol therapy.

• Hypotension: 27.4% (vs. 23.2% with placebo)
• Bradycardia: 15.9% (vs. 6.7%)
• Heart block (2nd/3rd degree): 4.7%
• Heart failure: Comparable with placebo (~27%)
• Other: tiredness, dizziness, shortness of breath

Do not use in patients with:

• Severe bradycardia or heart block (2nd or 3rd degree) without a pacemaker.

• Cardiogenic shock or decompensated heart failure.

• Hypersensitivity to metoprolol or other beta-blockers.

Bradycardia: Can progress to heart block or cardiac arrest.

Heart failure: May worsen; adjust diuretic therapy as needed.

Bronchospastic disease: Use with caution; bronchodilators should be on hand.

Pheochromocytoma: Only administer after alpha-blocker has been started.

Hypoglycemia: May mask early warning signs and prolong recovery, particularly in diabetics and fasting patients.

Peripheral vascular disease: May exacerbate symptoms of arterial insufficiency.