Metoprolol

# Metoprolol ## Overview - **Classification**: Beta-1 selective adrenergic blocker (beta-blocker) - **Mechanism**: Competitively blocks beta-1 adrenergic receptors, primarily in the heart, reducing heart rate, cardiac contractility, and blood pressure. ## Primary Indications 1. **Hypertension** - Management of high blood pressure. 2. **Angina Pectoris** - Prophylaxis of effort-induced angina. 3. **Myocardial Infarction** - Early intervention and long-term secondary prevention. 4. **Heart Failure (Metoprolol Succinate ER only)** - Management of stable, symptomatic chronic heart failure. ## Adult Dosing ### Standard Dosing **Hypertension** - **Metoprolol Tartrate (Immediate Release)** - **Dose**: **25-100 mg** - **Frequency**: **Twice daily** - **Route**: Oral - **Maximum Dose**: **450 mg/day** - **Metoprolol Succinate (Extended Release)** - **Dose**: **25-100 mg** - **Frequency**: **Once daily** - **Route**: Oral - **Maximum Dose**: **400 mg/day** **Angina Pectoris** - **Metoprolol Tartrate (Immediate Release)** - **Dose**: **50-100 mg** - **Frequency**: **Twice daily** - **Route**: Oral - **Maximum Dose**: **400 mg/day** - **Metoprolol Succinate (Extended Release)** - **Dose**: **100-400 mg** - **Frequency**: **Once daily** - **Route**: Oral - **Maximum Dose**: **400 mg/day** **Heart Failure (Metoprolol Succinate Extended Release Only)** - **Dose**: Initial **12.5-25 mg** - **Frequency**: **Once daily** - **Route**: Oral - **Titration**: Double dose every 2 weeks as tolerated - **Maximum Dose**: **200 mg/day** ### Dose Adjustments - **Renal Impairment**: No dose adjustment needed. - **Hepatic Impairment**: Use with caution. Consider lower initial doses and careful titration in severe impairment. - **Elderly Patients**: No specific adjustment, but monitor closely for bradycardia or hypotension. ## Pediatric Dosing *(Note: Use in pediatric patients is often off-label for hypertension or arrhythmias, and typically with Metoprolol Tartrate.)* ### Neonates (0-28 days) - **Dose**: Not routinely recommended for hypertension. Highly specialized use (e.g., supraventricular tachycardia) with **0.1-0.2 mg/kg/dose** IV. - **Frequency**: Administered under strict monitoring. - **Special Notes**: Limited data; individualize therapy. ### Infants (1-12 months) - **Dose**: For hypertension, typically not first-line. Limited off-label use **0.5-1 mg/kg/day** - **Frequency**: Divided **twice daily** (BID). - **Maximum**: Not to exceed **2 mg/kg/day** initially. ### Children (1-12 years) - **Indication**: Hypertension (off-label) - **Dose**: Initial **0.5-1 mg/kg/day** - **Frequency**: Divided **twice daily** (BID). - **Maximum**: Up to **2 mg/kg/day** or **100 mg/day**, whichever is less. Do not exceed adult maximum of **450 mg/day** (tartrate). - **Special Notes**: Start low and titrate based on response. ### Adolescents (13-18 years) - **Dose**: Approach adult dosing, starting at lower end of adult range. - **Frequency**: Refer to adult guidelines for tartrate or succinate. - **Maximum**: Adult maximum dose **450 mg/day** (tartrate) or **400 mg/day** (succinate). ## Safety Information ### Contraindications - **Absolute**: Severe bradycardia (<45-50 bpm) - **Absolute**: Second- or third-degree atrioventricular (AV) block - **Absolute**: Sick sinus syndrome (without a pacemaker) - **Absolute**: Cardiogenic shock - **Absolute**: Decompensated heart failure - **Absolute**: Severe peripheral arterial disease (risk of exacerbation) - **Relative**: Bronchial asthma or severe chronic obstructive pulmonary disease (COPD) ### Common Adverse Effects - **Very Common (>10%)**: Fatigue, dizziness - **Common (1-10%)**: Bradycardia, hypotension, nausea, diarrhea, shortness of breath, depression, cold extremities - **Serious but Rare**: Severe bronchospasm, heart failure exacerbation, significant AV block, severe allergic reaction ### Key Drug Interactions - **CYP2D6 Inhibitors (e.g., Fluoxetine, Paroxetine, Quinidine)**: May significantly increase metoprolol concentrations. Monitor for increased beta-blocker effects. - **Calcium Channel Blockers (e.g., Verapamil, Diltiazem)**: Increased risk of bradycardia, hypotension, or AV block. Avoid co-administration or monitor very closely. - **Digoxin**: Increased risk of bradycardia. Monitor heart rate. - **Clonidine**: Risk of rebound hypertension if clonidine is discontinued abruptly while on metoprolol. - **MAOIs**: May enhance hypotensive effect. ## Monitoring & Follow-up - **Before Treatment**: Baseline blood pressure (BP), heart rate (HR). ECG if cardiac history. - **During Treatment**: BP and HR regularly (e.g., weekly initially, then monthly). Monitor for symptoms of bradycardia or hypotension. - **Clinical Signs**: Watch for dizziness, fainting, shortness of breath, excessive fatigue, or swelling. ## Clinical Pearls - 💡 **Titration**: Always titrate slowly, especially for heart failure, to minimize adverse effects. - 💡 **Abrupt Withdrawal**: Do not stop metoprolol abruptly due to risk of rebound hypertension, angina exacerbation, or myocardial infarction. Taper over 1-2 weeks. - 💡 **Administration**: Metoprolol Succinate (ER) tablets can be divided, but not crushed or chewed. Administer with or immediately following meals. - 💡 **Masking Hypoglycemia**: May mask symptoms of hypoglycemia (tachycardia) in diabetic patients. > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.