Lopressor (metoprolol tartrate) is a cardioselective beta-1 adrenergic receptor blocking agent indicated for the management of hypertension, angina pectoris, and hemodynamically stable myocardial infarction. As a cornerstone in cardiovascular pharmacotherapy, it modulates sympathetic nervous system activity, reducing heart rate, myocardial contractility, and blood pressure. Its targeted mechanism offers a favorable risk-benefit profile for long-term cardiovascular risk reduction when administered under appropriate medical supervision.

Features

• Active ingredient: Metoprolol tartrate
• Pharmacologic class: Beta-1 selective adrenergic receptor blocker
• Available formulations: Immediate-release tablets (25 mg, 50 mg, 100 mg) and extended-release formulations
• Half-life: Approximately 3–7 hours (immediate-release)
• Metabolism: Hepatic, primarily via CYP2D6 isoenzyme
• Excretion: Renal (≤10% unchanged)
• Bioavailability: Approximately 50% (immediate-release)

Benefits

• Reduces systolic and diastolic blood pressure through decreased cardiac output and sympathetic outflow
• Decreases myocardial oxygen demand by lowering heart rate and contractility, providing antianginal protection
• Improves long-term cardiovascular outcomes post-myocardial infarction when initiated early
• May reduce mortality in heart failure with reduced ejection fraction when used with standard therapy
• Provides rhythm control in certain tachyarrhythmias through AV nodal conduction slowing
• Offers once or twice-daily dosing options for improved adherence

Common use

Lopressor is primarily prescribed for the management of essential hypertension, either as monotherapy or in combination with other antihypertensive agents. It is also indicated for the long-term treatment of chronic stable angina pectoris and for the early intervention in hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality. Off-label uses include migraine prophylaxis, symptomatic control of hyperthyroidism, and management of certain anxiety disorders with cardiovascular manifestations.

Dosage and direction

Hypertension: Initial dose 50 mg twice daily or 100 mg once daily (extended-release); may be increased at weekly intervals to maximum 400 mg daily. Angina: 50 mg twice daily or 100 mg once daily (extended-release); maximum 400 mg daily. Myocardial infarction: Early treatment with 5 mg IV every 2 minutes for 3 doses, followed by 50 mg orally every 6 hours for 48 hours, then 100 mg twice daily. Dosage must be individualized based on therapeutic response and tolerability. Administer with or immediately following meals to enhance bioavailability. Do not crush or chew extended-release tablets.

Precautions

Monitor blood pressure and heart rate regularly, especially during dosage titration. Use caution in patients with compensated heart failure; may precipitate overt failure. May mask signs of hypoglycemia in diabetic patients. Can exacerbate symptoms of peripheral vascular disease. Abrupt withdrawal may cause rebound hypertension, tachycardia, or angina exacerbation—taper gradually over 1–2 weeks. Use lower doses in elderly patients and those with hepatic impairment. May cause fatigue or dizziness—caution when operating machinery.

Contraindications

Severe bradycardia (heart rate <45–50 bpm), sick sinus syndrome, or second- and third-degree heart block without pacemaker. Cardiogenic shock, decompensated heart failure requiring IV inotropic therapy. Hypersensitivity to metoprolol or other beta-blockers. Severe peripheral arterial circulatory disorders. Concurrent use with flutter/fibrillation patients taking CYP2D6 inhibitors without dose adjustment.

Possible side effect

Common (>10%): Fatigue, dizziness, depression, bradycardia, diarrhea. Less common (1–10%): Shortness of breath, cold extremities, insomnia, nightmares, wheezing. Rare (<1%): Heart failure exacerbation, AV block, hepatotoxicity, thrombocytopenia, hallucinations. Most side effects are dose-dependent and often diminish with continued therapy or dosage reduction.

Drug interaction

Potentiators: CYP2D6 inhibitors (fluoxetine, paroxetine, quinidine) may increase metoprolol levels. Additive effects: Other beta-blockers, calcium channel blockers (verapamil, diltiazem), digoxin (increased bradycardia risk). Antagonists: Beta-2 agonists (bronchodilator effect reduced). NSAIDs: May diminish antihypertensive effect. Clonidine: Exaggerated rebound hypertension if discontinued concurrently. Antidiabetics: Masked hypoglycemic symptoms.

Missed dose

If a dose is missed, take it as soon as remembered unless it is nearly time for the next dose. Do not double the dose to make up for a missed one. If using twice-daily dosing and more than 4 hours have passed since the missed dose, skip and resume regular schedule. For once-daily formulations, if remembered within 12 hours, take immediately; otherwise, skip and resume next day.

Overdose

Symptoms include severe bradycardia, hypotension, heart failure, bronchospasm, hypoglycemia, and coma. Treatment involves gastric lavage if recent ingestion. Administer IV atropine for bradycardia. IV beta-agonists (isoproterenol) or phosphodiesterase inhibitors may be required. Glucagon has been used successfully. Cardiac pacing and vasopressors may be necessary for refractory cases. Hemodialysis is not effective due to high protein binding.

Storage

Store at controlled room temperature (20–25°C or 68–77°F). Protect from moisture and light. Keep in original container with tight closure. Do not store in bathroom or damp areas. Keep out of reach of children and pets. Do not use after expiration date printed on packaging.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Lopressor is a prescription medication that should be used only under the supervision of a qualified healthcare provider. Individual response to therapy may vary. Always follow your physician’s instructions regarding dosage and administration. Report any adverse effects to your healthcare provider immediately.

Reviews

Clinical studies demonstrate Lopressor reduces cardiovascular mortality by approximately 36% in post-MI patients when initiated early. Hypertension trials show 12–15 mmHg systolic and 8–10 mmHg diastolic reductions with 100–200 mg daily dosing. Angina patients report 40–50% reduction in attack frequency and nitrate use. Tolerability profile remains favorable with proper patient selection, though 10–15% discontinue due to side effects, primarily fatigue and bradycardia. Long-term adherence rates exceed 70% with appropriate patient education.