Metoprolol

Generic Name: Metoprolol
Common Brand Names: Lopressor, Toprol XL, Betaloc

Introduction

Metoprolol is a selective beta-1 adrenergic receptor blocker used extensively in cardiovascular medicine. It reduces heart rate, myocardial contractility, and cardiac output, making it a cornerstone therapy for hypertension, ischemic heart disease, and certain types of arrhythmias.

Conditions of Use (Indications)

1. Hypertension:

• First-line or adjunct therapy to control high blood pressure.

2.Ischemic Heart Disease:

• Management of angina pectoris to reduce myocardial oxygen demand.

3. Heart Failure (HFrEF):

• Improves survival and reduces hospitalizations in stable chronic heart failure.

4. Acute Myocardial Infarction (AMI):

• Reduces mortality and the risk of recurrent infarction.

5. Arrhythmias:

• Supraventricular tachycardia (SVT) and atrial fibrillation with rapid ventricular response.

6. Migraine Prophylaxis:

• Off-label use for reducing the frequency and severity of migraines.

Mechanism of Action

Metoprolol selectively inhibits beta-1 adrenergic receptors in the heart, leading to decreased heart rate (negative chronotropic effect), myocardial contractility (negative inotropic effect), and conduction velocity through the AV node (negative dromotropic effect). These effects reduce myocardial oxygen consumption and provide cardioprotection.

• Metoprolol Tartrate: Short-acting formulation.
• Metoprolol Succinate: Extended-release formulation for once-daily dosing.

Side Effects

1. Common Side Effects:

• Fatigue, dizziness, bradycardia, hypotension, depression.

2. Serious Side Effects:

• Worsening heart failure, bronchospasm (in susceptible patients), heart block, severe bradycardia.

Harmful Interactions

1.Calcium Channel Blockers (e.g., verapamil, diltiazem):

• Additive negative effects on heart rate and AV conduction.

2. Non-Dihydropyridine Calcium Channel Blockers:

• Increased risk of severe bradycardia and heart block.

3.CYP2D6 Inhibitors (e.g., fluoxetine, paroxetine):

• Prolonged action of metoprolol due to reduced metabolism.

Contraindications

1. Severe bradycardia.
2. Second- or third-degree AV block (without a pacemaker).
3. Cardiogenic shock.
4. Decompensated heart failure.
5. Hypersensitivity to beta-blockers.

Latest References

1. European Society of Cardiology (ESC) Guidelines for Heart Failure (2023).
2. JACC (2023): Beta-Blockers in Hypertension and Heart Failure.
3. NICE Guidelines for Beta-Blockers in Cardiovascular Disease (2023).