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metoprolol succinate
Toprol XL

metoprolol tartrate
Apo-Metoprolol†, Apo-Metoprolol (Type L)†, Betaloc†‡, Betaloc
Durules†, Lopresor†, Lopresor SR†, Lopressor, Minax‡, Novo-Metoprol†, Nu-Metop†

Pregnancy Risk Category C

How supplied
metoprolol succinate

Tablets (extended-release):
50 mg, 100 mg, 200 mg
metoprolol tartrate

Tablets:
50 mg, 100 mg
Tablets (extended-release):
100 mg†, 200 mg†
Injection:
1 mg/ml in 5-ml ampules

Action
Unknown. A beta blocker that decreases myocardial contractility, heart rate, cardiac output, and blood pressure and reduces myocardial oxygen use. Also depresses renin secretion.

Indications & dosage
Hypertension
--
Adults:
initially, 50 mg P.O. b.i.d. or 100 mg P.O. once daily; then up to 100 to 450 mg daily in two or three divided doses. Or, 50 to 100 mg of extended-release tablets (tartrate equivalent) once daily. Dosage is adjusted as needed and tolerated at intervals of not less than 1 week to maximum of 400 mg daily.
Early intervention in acute MI (metoprolol tartrate)
--
Adults:
three 5-mg I.V. boluses q 2 minutes. Then, beginning 15 minutes after last dose, 25 to 50 mg P.O. q 6 hours for 48 hours. Maintenance dose is 100 mg P.O. b.i.d. for 3 months to 3 years.
Angina pectoris
--
Adults:
initially, 100 mg P.O. daily as a single dose or in two equally divided doses; increased at weekly intervals until an adequate response or a pronounced decrease in heart rate is seen. Effects of daily dose beyond 400 mg are not known. Or, give 100 mg of extended-release tablets (tartrate equivalent) once daily. Dose adjusted as needed and tolerated at intervals of not less than 1 week to maximum of 400 mg daily.

Adverse reactions
CNS:
fatigue, dizziness, depression.
CV:
bradycardia, hypotension, heart failure, AV block.
GI:
nausea, diarrhea.
Hepatic:
elevated serum transaminase, alkaline phosphatase, and LD levels.
Metabolic:
elevated uric acid levels.
Respiratory:
dyspnea.
Skin:
rash.

Interactions
Drug-drug.
Barbiturates, rifampin: increased metabolism of metoprolol. Monitor for decreased effect.
Cardiac glycosides, diltiazem, verapamil:
excessive bradycardia and increased depressant effect on myocardium. Use together cautiously.
Catecholamine-depleting drugs such as reserpine, H2 antagonists, MAO inhibitors:
may have additive effect when given with beta blockers. Monitor for hypotension and bradycardia.
Chlorpromazine, cimetidine, verapamil:
decreased hepatic clearance. Monitor for greater beta-blocking effect.
Indomethacin:
decreased antihypertensive effect. Monitor blood pressure and adjust dosage.
Insulin, oral antidiabetics:
can alter dosage requirements in previously stabilized diabetic patients. Observe patient carefully.
Propafenone
: may increase metoprolol serum levels. Monitor vital signs.
Terbutaline
: may antagonize bronchodilatory effects of terbutaline. Monitor patient.
Drug-food.
Any food: may increase absorption. Give drug with food.

Effects on diagnostic tests
None reported.

Contraindications
Contraindicated in patients with hypersensitivity to drug or other beta blockers. Also contraindicated in patients with sinus bradycardia, heart block greater than first-degree, cardiogenic shock, or overt cardiac failure when used to treat hypertension or angina. When used to treat MI, drug is contraindicated in patients with heart rate less than 45 beats/minute, second- or third-degree heart block, PR interval of 0.24 seconds or longer with first-degree heart block, systolic blood pressure below 100 mm Hg, or moderate to severe cardiac failure.

Nursing considerations

I.V. administration

Patient teaching

*Liquid contains alcohol. **May contain tartrazine.  †Canada  ‡Australia  §U.K.  OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING

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