#lopressor

Common Brand Names: Lopressor

Therapeutic Class: A beta-blocking cardiovascular agent

Common Injectable Dosage Forms:

Injection: 1 mg/mL in 5 mL ampules

Dosage Ranges:

For acute myocardial infarction:

Early Treatment: Three 5 mg IV bolus doses at approximately 2-minute intervals. 15 minutes after last IV dose, start 25-50 mg orally every 6 hours. Start treatment at first sign of suspected acute MI.

Late Treatment: For patients who have contraindications to treatment during the early phase of suspected or definite MI, in patients who appear to tolerate the full early treatment and in patients in whom the physician wishes to delay therapy for any reason should be given 100 mg orally twice daily for at least 3 months.

Administration and Stability: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Store at 25°C (77°F); excursions permitted to 15-30°C (59-86°F). Protect from light. pH 5-8

Pharmacology/Pharmacokinetics: Metoprolol is a relatively cardioselective beta-1-adrenergic receptor blocker which results in: (1) decreased heart rate and cardiac output; (2) a decrease in systolic and diastolic blood pressure; (3) an inhibition of isoproterenol tachycardia; and (4) a decrease of reflex orthostatic tachycardia. Metoprolol crosses the blood-brain barrier. Oral metoprolol undergoes first-pass metabolism of approximately 50%. Plasma half-life is 3-7 hours while 12% is bound to plasma proteins. Following intravenous administration over a 10-minute period, maximum beta blockade was achieved at approximately 20 minutes.

Drug and Lab Interactions: May decrease the effects of theophylline. Barbiturates or rifampin may decrease effects. Cimetidine may increase serum effects. Hydralazine, propafenone, or thioamides may increase effects. Nonsteroidal anti-inflammatory agents may decrease effects. Toxic effects may be increased with VERAPAMIL. May increase toxic effects of lidocaine. Use with prazosin may increase postural hypotension.

Contraindications/Precautions: Use is contraindicated in patients with sinus bradycardia, heart block greater than first degree, cardiogenic shock, congestive heart failure, overt heart failure, with heart rate <45 beats per minute, a systolic blood pressure <100 mmHg, or moderate-to-severe cardiac failure. Use with caution in pregnancy, in patients with bronchospastic diseases, diabetes, thyrotoxicosis, and impaired renal function. Pregnancy Category C.

Monitoring Parameters: Serum electrolytes (potassium, sodium, chloride, bicarbonate), renal function, and blood pressure

Adverse Effects: Dizziness, fatigue, depression, shortness of breath, diarrhea, and bradycardia

Brand Name: Lopressor

Generic Available

Common Dosage Forms:

Tablets: 25 mg, 50 mg, 100 mg

Injection: 5 mg/5 mL

FDA Indications/Dosages:

Management of hypertension: Initial: 100 mg daily in a single or divided dose. May increase doses at weekly (or longer) intervals. Maintenance: 100-450 mg per day in a single or divided dose.

Acute myocardial infarction: Early treatment: Three 5 mg IV bolus at approximately 2-minute intervals. 15 minutes after last IV bolus, start with 25-50 orally every 6 hours. Late treatment: 100 mg twice daily for at least 3 months. Start maintenance dose 48 hours after last IV dose.

Pharmacology/Pharmacokinetics: Metoprolol is a relatively cardioselective beta-1 adrenergic receptor blocker which results in: (1) decreased heart rate and cardiac output; (2) a decrease in systolic and diastolic blood pressure; (3) an inhibition of isoproterenol tachycardia; and (4) a decrease of reflex orthostatic tachycardia. Metoprolol crosses the blood-brain barrier, undergoes first-pass metabolism and is excreted in the urine. Metoprolol plasma half-life is 3-7 hours. 12% is bound to plasma proteins.

Drug Interactions: May decrease effects of theophylline. Barbiturates or rifampin may decrease effects. Cimetidine may increase serum levels. Hydralazine, propafenone, or thioamides may increase effects. Nonsteroidal anti-inflammatory agents may decrease effects. Toxic effects may be increased with VERAPAMIL. May increase toxic effects of lidocaine. Use with prazosin may increase postural hypotension. Use with digitalis may cause additive bradycardia.

Contraindications/Precautions: Use is contraindicated in patients with sinus bradycardia, heart block greater than first degree, cardiogenic shock, congestive heart failure, overt cardiac failure, and in patients with heart rate <45 beats per minute, systolic blood pressure <100 mmHg, or moderate to severe cardiac failure. Use with caution in pregnancy, in patients with bronchospastic diseases, diabetes, thyrotoxicosis, and in impaired hepatic function. Pregnancy Category C.

Adverse Effects: Dizziness, fatigue, depression, shortness of breath, diarrhea, and bradycardia.

Patient Consultation:

Contact a physician is the above effects are severe or persistent.

Do not discontinue therapy without first consulting a physician.

Take with food to increase absorption.

May cause dizziness. Use caution while operating machinery.

Patients with diabetes need to be aware that this agent can cause masking of hypoglycemic symptoms.

Store in a cool, dry place away from sunlight and children.