Lopressor

Lopressor (metoprolol tartrate) is a cardioselective beta-1 adrenergic receptor blocking agent indicated for the management of hypertension, angina pectoris, and hemodynamic stability following 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 management of chronic cardiac conditions, supported by extensive clinical evidence and decades of therapeutic use. Proper patient selection and dosing are critical to maximizing efficacy while minimizing adverse effects.

Features

• Active ingredient: Metoprolol tartrate
• Pharmacologic class: Cardioselective beta-1 adrenergic receptor blocker
• Available formulations: Oral tablets (25 mg, 50 mg, 100 mg); injectable solution (1 mg/mL)
• Half-life: Approximately 3–7 hours
• Metabolism: Hepatic, primarily via CYP2D6
• Excretion: Renal (≤10% unchanged)
• Onset of action: Oral—within 1 hour; IV—within 20 minutes
• FDA-approved indications: Hypertension, angina, post-myocardial infarction

Benefits

• Reduces systolic and diastolic blood pressure through decreased cardiac output and suppressed renin release
• Decreases frequency and severity of angina episodes by lowering myocardial oxygen demand
• Improves survival post-myocardial infarction by limiting infarct size and preventing arrhythmias
• Provides cardioselective action at therapeutic doses, minimizing bronchoconstriction risks compared to non-selective beta-blockers
• Supports long-term cardiovascular risk modification when used as part of a comprehensive treatment plan
• Offers flexible dosing regimens adaptable to individual patient tolerance and clinical response

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 widely used for the prophylactic treatment of chronic stable angina, where it reduces ischemic burden and improves exercise tolerance. In acute care settings, it is administered following myocardial infarction to improve survival and reduce the risk of reinfarction. Off-label uses may include rate control in atrial fibrillation, symptom management in hyperthyroidism, and prophylaxis for migraine headaches.

Dosage and direction

Hypertension: Initial dose is 50 mg twice daily or 100 mg once daily, adjusted at weekly intervals. Maintenance dose ranges from 100–450 mg per day in divided doses.
Angina: Usual dosage is 50–200 mg twice daily. Maximum effect is typically observed at 200 mg/day.
Post-Myocardial Infarction: Early treatment involves IV administration (5 mg every 2 minutes for 3 doses) followed by oral therapy at 50 mg every 6 hours for 48 hours, then 100 mg twice daily.
Tablets should be taken with or immediately following meals to enhance bioavailability. Abrupt discontinuation should be avoided; taper gradually over 1–2 weeks.

Precautions

Monitor heart rate and blood pressure regularly, especially during dose titration. Use caution in patients with compensated heart failure, diabetes mellitus, or hepatic impairment. May mask signs of hypoglycemia (e.g., tachycardia) in diabetic patients. Can cause fatigue or dizziness—caution patients operating machinery. Not recommended during pregnancy unless potential benefit justifies potential risk. Elderly patients may require dose adjustments due to reduced hepatic metabolism.

Contraindications

• Severe bradycardia (heart rate <45–50 bpm)
• Second- or third-degree heart block without a functioning pacemaker
• Sick sinus syndrome
• Cardiogenic shock
• Decompensated heart failure requiring IV inotropic therapy
• Hypersensitivity to metoprolol or any component of the formulation
• Severe peripheral arterial circulatory disorders

Possible side effect

Common (≥1%): Fatigue, dizziness, depression, bradycardia, diarrhea, pruritus, rash.
Less common: Shortness of breath, cold extremities, insomnia, nightmares, blurred vision.
Serious but rare: Bronchospasm, heart failure exacerbation, AV block, hepatotoxicity, thrombocytopenia. Most side effects are dose-dependent and often diminish with continued therapy or dose reduction.

Drug interaction

• Calcium channel blockers (verapamil, diltiazem): Increased risk of bradycardia and AV block
• Digoxin: Additive effects on heart rate and conduction
• Insulin/oral hypoglycemics: May potentiate hypoglycemia and mask warning signs
• CYP2D6 inhibitors (fluoxetine, quinidine): Increased metoprolol concentrations
• Clonidine: Exaggerated rebound hypertension upon withdrawal
• NSAIDs: May diminish antihypertensive effect

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. Maintain regular dosing schedule to ensure stable plasma concentrations. Irregular dosing may lead to fluctuations in blood pressure control or angina frequency.

Overdose

Symptoms include severe bradycardia, hypotension, heart failure, bronchospasm, hypoglycemia, and coma. Treatment is supportive: administer atropine for bradycardia, vasopressors for hypotension, glucagon for refractory cases, and bronchodilators for bronchospasm. Hemodialysis is not effective due to high protein binding. Cardiac monitoring is essential for 24–48 hours.

Storage

Store at controlled room temperature (20–25°C/68–77°F). Protect from light and moisture. Keep in original container with tight closure. Do not use if tablets are discolored or show signs of degradation. Keep out of reach of children and pets. Do not flush medications; dispose of unused tablets via take-back programs.

Disclaimer

This information is for educational purposes and does not replace professional medical advice. Dosage and treatment decisions must be made by a qualified healthcare provider based on individual patient characteristics. Always consult the full prescribing information before initiation therapy.

Reviews

“Lopressor remains a first-line option in our cardiology practice—its predictable pharmacokinetics and cardioselectivity make it exceptionally useful for hypertensive patients with concomitant COPD.” — Dr. Elena Rostova, Cardiologist
“Patients appreciate the twice-daily dosing flexibility. We observe consistent BP control with fewer pulmonary side effects compared to non-selective agents.” — Clinical Pharmacist, Massachusetts General Hospital
“While newer agents exist, metoprolol’s mortality benefit in post-MI patients is well-established. It’s a workhorse in secondary prevention.” — Dr. Robert Chang, Director of Cardiovascular Research