metoprolol, Lopressor, Toprol XL (cont.)

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Medical and Pharmacy Editor:

PREGNANCY: Safe use of metoprolol during pregnancy has not been established.

NURSING MOTHERS: Small quantities of metoprolol are excreted in breast milk and may potentially cause adverse effects in the infant.

SIDE EFFECTS: Metoprolol is generally well tolerated. Side effects include abdominal cramps, diarrhea, constipation, fatigue, insomnia, nausea, depression, dreaming, memory loss, fever, impotence, lightheadedness, slow heart rate, low blood pressure, cold extremities, sore throat, and shortness of breath or wheezing. Metoprolol can aggravate breathing difficulties in patients with asthma, chronic bronchitis, or emphysema.

In patients with existing slow heart rates (bradycardias) and heart blocks (defects in the electrical conduction of the heart), metoprolol can cause dangerously slow heart rates, and even shock. Metoprolol reduces the force of heart muscle contraction and can aggravate symptoms of heart failure. In patients with coronary artery disease, abruptly stopping metoprolol can suddenly worsen angina, and occasionally precipitate heart attacks. If it is necessary to discontinue metoprolol, its dosage should be reduced gradually over several weeks.

Initiation of high-dose extended release metoprolol in patients undergoing non-cardiac surgery is associated with bradycardia (slow heart rate), hypotension, stroke, and death. However, long-term therapy with metoprolol should not be routinely withdrawn prior to major surgery. Impaired ability of the heart to respond to reflex adrenergic stimuli may increase the risks of general anesthesia and surgery.

Reference: FDA Prescribing Information


Medically Reviewed by a Doctor on 10/21/2013


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