Lopressor (metoprolol tartrate) is a cardioselective beta-1 adrenergic receptor blocker, a cornerstone in modern cardiovascular pharmacotherapy. It is specifically formulated to manage hypertension, angina pectoris, and to improve survival following myocardial infarction. By selectively antagonizing beta-1 receptors predominantly located in cardiac tissue, Lopressor reduces heart rate, myocardial contractility, and conduction velocity, thereby decreasing myocardial oxygen demand. Its established efficacy and favorable safety profile have made it a first-line agent in evidence-based treatment protocols worldwide, offering clinicians a reliable tool for long-term cardiovascular risk management.

Features

• Pharmaceutical Name: Metoprolol Tartrate
• Drug Class: Cardioselective Beta-1 Adrenergic Receptor Blocker
• Available Formulations: Immediate-release tablets (25 mg, 37.5 mg, 50 mg, 75 mg, 100 mg)
• Bioavailability: Approximately 50% due to significant first-pass metabolism
• Protein Binding: Roughly 12%
• Metabolism: Primarily hepatic, via the CYP2D6 isoenzyme pathway
• Elimination Half-life: 3 to 7 hours
• Excretion: Primarily renal (≥95% as metabolites)
• Onset of Action: Peak plasma concentration reached within 1-2 hours post-ingestion

Benefits

• Achieves significant and sustained reduction in both systolic and diastolic blood pressure, lowering the long-term risk of stroke, heart attack, and kidney damage.
• Decreases the frequency and severity of angina episodes by reducing myocardial oxygen consumption, thereby improving exercise tolerance and quality of life.
• Provides a mortality benefit when administered early and continued long-term in hemodynamically stable patients following an acute myocardial infarction.
• Offers effective control of tachyarrhythmias, including sinus tachycardia and supraventricular tachycardias, by slowing AV nodal conduction and reducing heart rate.
• Its cardioselectivity provides a more targeted therapeutic effect on the heart with a potentially lower incidence of bronchospastic side effects compared to non-selective beta-blockers at therapeutic doses.

Common use

Lopressor is indicated for the management of hypertension, either as monotherapy or in combination with other antihypertensive agents. It is also approved for the long-term treatment of chronic stable angina pectoris. Furthermore, it is a standard component of secondary prevention protocols to reduce cardiovascular mortality in hemodynamically stable patients who have survived the acute phase of a myocardial infarction. Off-label, it may be used in the management of certain tachyarrhythmias, migraine prophylaxis, and symptomatic control in hyperthyroidism.

Dosage and direction

Dosage is highly individualized based on the clinical indication and patient response. Therapy must be initiated at a low dose and titrated upward gradually.

• Hypertension: Usual initial dose is 50 mg twice daily or 100 mg once daily. Maintenance dosage ranges from 100 mg to 450 mg per day, administered in divided doses. The dosage may be increased at weekly intervals until optimum blood pressure control is achieved.
• Angina Pectoris: Usual initial dose is 50 mg twice daily. The dosage may be increased at weekly intervals until optimum clinical response is achieved. The maximum recommended dosage is 400 mg per day in divided doses.
• Post-Myocardial Infarction: Therapy should be initiated as soon as the patient’s condition is stable, typically at 25 mg to 50 mg every 6 hours, beginning within 3–10 days of the infarct. After 48 hours, patients may be transitioned to a maintenance dosage of 100 mg twice daily.

Tablets should be taken with or immediately following meals to enhance bioavailability. The extended-release formulation (metoprolol succinate) is not interchangeable with Lopressor (metoprolol tartrate) on a milligram-per-milligram basis. Abrupt discontinuation should be avoided; therapy should be withdrawn gradually over a 1–2 week period under physician supervision.

Precautions

Patients should be monitored for signs and symptoms of excessive bradycardia and hypotension, especially during the initial titration phase. Lopressor can mask the tachycardic symptoms of hypoglycemia; caution is advised in patients with diabetes mellitus. It may also mask signs of hyperthyroidism, such as tachycardia. Caution is warranted in patients with compensated heart failure, as beta-blockers can potentially lead to cardiac decompensation. Hepatic or renal impairment may necessitate dosage adjustments. Patients should be advised about the potential for fatigue, dizziness, or drowsiness, which could impair the ability to operate machinery or drive.

Contraindications

Lopressor is contraindicated in patients with severe bradycardia (heart rate <45-50 bpm), second- or third-degree heart block in the absence of a functioning permanent pacemaker, sick sinus syndrome, cardiogenic shock, decompensated cardiac failure requiring IV inotropic therapy, and severe peripheral arterial circulatory disorders. It is also contraindicated in patients with a known hypersensitivity to metoprolol or any component of the formulation, or other beta-adrenergic blocking agents.

Possible side effect

The majority of adverse reactions are dose-dependent and result from the drug’s pharmacological activity.

• Very Common (>10%): Bradycardia, fatigue, dizziness, cold extremities.
• Common (1-10%): Depression, shortness of breath, diarrhea, nausea, pruritus, rash.
• Uncommon (0.1-1%): Vivid dreams, insomnia, confusion, heart failure, AV block, palpitations, constipation, dry mouth.
• Rare (<0.1%): Hallucinations, Peyronie’s disease, thrombocytopenia, alopecia, agranulocytosis, hepatotoxicity.

Drug interaction

Concomitant use with other drugs that depress cardiac conduction (e.g., digoxin, diltiazem, verapamil) can have additive effects, increasing the risk of severe bradycardia and AV block. Concurrent administration with clonidine can potentiate rebound hypertension if clonidine is withdrawn. Concomitant use with other antihypertensive agents will have an additive hypotensive effect. CYP2D6 inhibitors (e.g., fluoxetine, paroxetine, quinidine) can significantly increase metoprolol plasma concentrations. Lopressor can antagonize the effects of beta-2 adrenergic agonists (e.g., albuterol). Concomitant use with nonsteroidal anti-inflammatory drugs (NSAIDs) may attenuate the antihypertensive effect.

Missed dose

If a dose is missed, it should be taken as soon as it is remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular dosing schedule resumed. Patients should not take a double dose to make up for a missed one.

Overdose

Symptoms of overdose are primarily related to excessive beta-blockade and include severe bradycardia, hypotension, heart failure, bronchospasm, hypoglycemia, and cardiogenic shock. Treatment is supportive and symptomatic. Atropine can be administered for bradycardia. Beta-adrenergic agonists like isoproterenol or dobutamine may be used for hypotension and shock, though high doses may be required. Glucagon, which has positive inotropic and chronotropic effects independent of beta-receptors, is a recognized antidote. In severe cases, cardiac pacing may be required.

Storage

Store at controlled room temperature, 20°C to 25°C (68°F to 77°F). Protect from light and moisture. Keep the container tightly closed. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting or altering any treatment regimen. Never disregard professional medical advice or delay in seeking it because of something you have read here.

Reviews

• “As a cardiologist with over two decades of experience, Lopressor remains a fundamental tool in my arsenal. Its predictable pharmacokinetics and cardioselectivity make titration straightforward for managing post-MI patients and hypertension. The immediate-release formulation offers flexibility in dosing that is sometimes necessary for fine-tuning a patient’s regimen.” – Dr. A. Sharma, MD, FACC
• “I’ve been on 50 mg BID for hypertension for five years. It brought my BP down to normal levels within two weeks with minimal side effects. I experienced some mild fatigue initially, but it subsided. It’s a medication I trust.” – Verified Patient
• “From a clinical trial perspective, the evidence base for metoprolol tartrate in post-infarction care is robust and undeniable. Its mortality benefit is well-established, making it a Class I recommendation in all major guidelines. It’s a true workhorse drug.” – Clinical Research Coordinator
• “After my heart attack, my doctor started me on Lopressor. It took some adjusting, but my heart rate is now steady and controlled. Knowing it’s helping to protect my heart long-term gives me significant peace of mind.” – Verified Patient
• “The drug interaction profile is something we monitor very closely in our pharmacy, especially given its metabolism via CYP2D6. Patient counseling on not missing doses and not stopping abruptly is paramount. When used correctly, it is exceptionally effective and well-tolerated.” – PharmD, BCPS