• Basic Info
• Top Questions
• Clinical Info
• Interactions

Stability

Storage

Oral

Tablets

Tight, light-resistant containers at 15–30°C. Protect from light.

Extended-Release Tablets

25°C (may be exposed to 15–30°C).

Parenteral

Injection

30°C or less (preferably 15–30°C). Protect from light and freezing.

Compatibility

Parenteral

Solution Compatibility

Drug Compatibility

Actions

• Inhibits response to adrenergic stimuli by competitively blocking β₁-adrenergic receptors within the myocardium. Blocks β₂-adrenergic receptors within bronchial and vascular smooth muscle only in high doses.
• Decreases resting heart rate, reflex orthostatic tachycardia, myocardial contractility, and cardiac output at rest and during exercise (without increasing peripheral resistance); inhibits exercise-induced increases in heart rate; increases systolic ejection time and cardiac volume, without changing stroke volume; decreases conduction velocity through the SA and AV nodes; and decreases myocardial automaticity.
• No intrinsic sympathomimetic activity and little or no membrane-stabilizing effect on the heart.
• Reduces BP by decreasing cardiac output, decreasing sympathetic outflow from the CNS, suppressing renin release, and/or reducing peripheral resistance.
• In patients with MI, reduces heart rate, systolic BP, cardiac output, and ventricular fibrillation.
• In patients with angina, blocks catecholamine-induced increases in heart rate, velocity and extent of myocardial contraction, and BP, resulting in decreased myocardial oxygen consumption.
• Increases airway resistance and decreases ventilatory capacity in asthmatic patients.
• Causes little inhibition of glycogenolysis in skeletal and cardiac muscles; inhibits increase in plasma glycerol during exercise; inhibits insulin release less than propranolol.

Advice to Patients

• Importance of taking metoprolol exactly as prescribed.
• Importance of not interrupting or discontinuing therapy without consulting clinician; patients should temporarily limit their physical activity when discontinuing therapy.
• If a dose is missed, importance of patient taking only the next scheduled dose (i.e., the next dose should not be doubled).
• Importance of immediately informing clinician at the first sign or symptom of impending cardiac failure (e.g., weight gain, increased shortness of breath) or if any difficulty in breathing occurs.
• In patients with heart failure, importance of informing clinician of signs or symptoms of exacerbation (e.g., weight gain, difficulty in breathing).
• Importance of patients informing anesthesiologist or dentist that they are receiving metoprolol therapy prior to undergoing major surgery.
• Importance of avoiding some activities (e.g., operating machinery, driving a motor vehicle) until effects on individual are known.
• Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs.
• Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.
• Importance of informing patients of other important precautionary information. (See Cautions.)