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Action/Kinetics:
Exerts mainly beta-1-adrenergic blocking activity although beta-2 receptors are blocked at high doses. Has no membrane stabilizing or intrinsic sympathomimetic effects. Moderate lipid solubility.
Onset: 15 min.
Peak plasma levels: 90 min.
t
1/2: 3-7 hr. Effect of drug is cumulative. Food increases bioavailability. Exhibits significant first-pass effect. Metabolized in liver and excreted in urine.
Uses:
Metoprolol Succinate: Alone or with other drugs to treat hypertension. Chronic management of angina pectoris.
Metoprolol Tartrate: Hypertension (either alone or with other antihypertensive agents, such as thiazide diuretics). Acute MI in hemodynamically stable clients. Angina pectoris.
Investigational: IV to suppress atrial ectopy in COPD, aggressive behavior, prophylaxis of migraine, ventricular arrhythmias, enhancement of cognitive performance in geriatric clients, essential tremors.
Additional Contraindications:
Myocardial infarction in clients with a HR of less than 45 beats/min, in second- or third-degree heart block, or if SBP is less than 100 mm Hg. Moderate to severe cardiac failure.
Special Concerns:
Safety and effectiveness have not been established in children. Use with caution in impaired hepatic function and during lactation.
Laboratory Test Alterations:
Serum transaminase, LDH, alkaline phosphatase.
Additional Drug Interactions:
-
Cimetidine / May
plasma metoprolol levels
-
Contraceptives, oral / May
metoprolol effects
-
Methimazole / May
metoprolol effects
-
Phenobarbital /
Metoprolol effect R/T
liver metabolism
-
Propylthiouracil / May
metoprolol effects
-
Quinidine / May
metoprolol effects
-
Rifampin /
Metoprolol effect R/T
liver metabolism
How Supplied:
Metoprolol succinate:
Tablet, Extended Release: 50 mg, 100 mg, 200 mg.
Metoprolol tartrate:
Injection: 1 mg/mL;
Tablet: 50 mg, 100 mg
Dosage
?Metoprolol Succinate Tablets
Angina pectoris.
Individualized. Initial: 100 mg/day in a single dose. Dose may be increased slowly, at weekly intervals, until optimum effect is reached or there is a pronounced slowing of HR. Doses above 400 mg/day have not been studied.
Hypertension.
Initial: 50-100 mg/day in a single dose with or without a diuretic. Dosage may be increased in weekly intervals until maximum effect is reached. Doses above 400 mg/day have not been studied.
?Metoprolol Tartrate Tablets
Hypertension.
Initial: 100 mg/day in single or divided doses;
then, dose may be increased weekly to maintenance level of 100-450 mg/day. A diuretic may also be used.
Aggressive behavior.
200-300 mg/day.
Essential tremors.
50-300 mg/day.
Prophylaxis of migraine.
50-100 mg b.i.d.
Ventricular arrhythmias.
200 mg/day.
?Metoprolol Tartrate Injection (IV) and Tablets
Early treatment of MI.
3 IV bolus injections of 5 mg each at approximately 2-min intervals. If clients tolerate the full IV dose, give 50 mg q 6 hr PO beginning 15 min after the last IV dose (or as soon as client's condition allows). This dose is continued for 48 hr followed by
late treatment: 100 mg b.i.d. as soon as feasible; continue for 1-3 months (although data suggest treatment should be continued for 1-3 years). In clients who do not tolerate the full IV dose, begin with 25-50 mg q 6 hr PO beginning 15 min after the last IV dose or as soon as the condition allows.
