5 WARNINGS AND PRECAUTIONS
Bradycardia, including sinus pause, heart block, and cardiac arrest have occurred with the use of Metoprolol tartrate. 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 tartrate. If severe bradycardia develops, reduce or stop Metoprolol tartrate.
5.2 Heart Failure
Worsening cardiac failure may occur during metoprolol use. If such symptoms occur, increase diuretics and restore clinical stability before administering the next dose of metoprolol [see Dosage and Administration (2)]. Such episodes do not preclude subsequent successful titration of oral metoprolol.
5.3 Bronchospastic Disease
PATIENTS WITH BRONCHOSPASTIC DISEASES, IN GENERAL, SHOULD NOT RECEIVE BETA-BLOCKERS because they can exacerbate bronchospasm. Because of its relative beta1 cardio-selectivity, however, metoprolol may be used in patients with bronchospastic disease for initial treatment of myocardial infarction. Bronchodilators, including beta2-agonists, should be readily available or administered concomitantly [see Dosage and Administration (2)].
If metoprolol tartrate 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.