| Recommended Dose and Dosage Regimen | The recommended dose of metoprolol varies depending on the indication and individual patient factors. For the treatment of hypertension, the usual starting dose of metoprolol tartrate immediate-release tablets is 25-50 mg orally once daily, with gradual titration based on blood pressure response. The maximum recommended dose is 100-450 mg daily, depending on the formulation and severity of hypertension. For the management of angina pectoris, the initial dose may range from 50-100 mg orally once daily. For the treatment of myocardial infarction or heart failure, the initial dose of metoprolol succinate extended-release tablets is 25-100 mg orally once daily, with gradual titration to target doses of 200 mg daily for heart failure. Dosage adjustments are necessary in patients with renal impairment, hepatic impairment, or concomitant use of other medications that affect cardiac function or blood pressure. Follow your healthcare provider’s instructions regarding dosing and administration. |
| Frequency of Administration | Metoprolol is typically administered orally once or twice daily, depending on the formulation and indication. Immediate-release formulations are often given twice daily to maintain therapeutic blood levels throughout the day, while extended-release formulations may be administered once daily for convenience and sustained efficacy. |
| Route of Administration | Metoprolol is available for oral administration in various formulations, including immediate-release tablets, extended-release tablets, and oral solutions. Intravenous formulations are also available for acute management of certain cardiovascular conditions. |
| Mechanism of Action (MOA) | Metoprolol is a selective beta-1 adrenergic receptor antagonist (beta-blocker) that competitively inhibits the binding of catecholamines such as epinephrine and norepinephrine to beta-1 adrenergic receptors in the heart and peripheral vasculature. By blocking beta-1 receptors, metoprolol reduces heart rate, myocardial contractility, and cardiac output, resulting in decreased oxygen demand and blood pressure. Metoprolol also inhibits sympathetic activity and renin release, leading to additional antihypertensive and antiarrhythmic effects. |
| Pharmacokinetics (PK) | Metoprolol is well absorbed after oral administration, with peak plasma concentrations reached within 1-2 hours for immediate-release formulations and 6-7 hours for extended-release formulations. It undergoes hepatic metabolism via the cytochrome P450 enzyme system, primarily CYP2D6, and is eliminated primarily in the urine as metabolites. The elimination half-life of metoprolol ranges from 3-7 hours, allowing for once- or twice-daily dosing, depending on the formulation. Metoprolol pharmacokinetics may be altered in patients with hepatic impairment or concomitant use of CYP2D6 inhibitors or inducers. |
| Pharmacodynamics (PD) | Metoprolol exerts its pharmacodynamic effects primarily by blocking beta-1 adrenergic receptors in the heart, resulting in negative chronotropic (reduced heart rate), inotropic (reduced myocardial contractility), and dromotropic (slowed atrioventricular conduction) effects. By reducing sympathetic stimulation of the heart, metoprolol decreases heart rate, cardiac output, and blood pressure, leading to antihypertensive, antianginal, and antiarrhythmic effects. Metoprolol also inhibits renin release from the kidneys, further reducing blood pressure through renin-angiotensin-aldosterone system (RAAS) blockade. |
| Pathophysiology | Metoprolol is indicated for the management of various cardiovascular conditions, including hypertension, angina pectoris, myocardial infarction, heart failure, and certain arrhythmias. Hypertension is characterized by elevated blood pressure that increases the risk of cardiovascular events such as stroke, myocardial infarction, and heart failure. Angina pectoris is caused by myocardial ischemia due to inadequate oxygen supply and increased demand, leading to chest pain or discomfort. Myocardial infarction results from acute coronary artery occlusion, leading to myocardial necrosis and impaired cardiac function. Heart failure is a chronic condition characterized by inadequate cardiac output and fluid retention, resulting in symptoms such as dyspnea, fatigue, and edema. Arrhythmias are abnormal heart rhythms that may disrupt normal cardiac function and lead to symptoms such as palpitations, dizziness, or syncope. |
| Primary Indications | Hypertension, angina pectoris, myocardial infarction, heart failure, certain arrhythmias. |
| Contraindications | Contraindications to metoprolol use include hypersensitivity to metoprolol or any component of the formulation, severe bradycardia, heart block greater than first degree, cardiogenic shock, decompensated heart failure, and overt cardiac failure. Metoprolol should not be used concomitantly with certain medications that may exacerbate bradycardia or heart block, such as non-dihydropyridine calcium channel blockers (e.g., verapamil, diltiazem), antiarrhythmic drugs (e.g., class Ia or III antiarrhythmics), or other beta-blockers. Use caution in patients with bronchospastic diseases, diabetes mellitus, peripheral vascular disease, or thyrotoxicosis, as metoprolol may exacerbate these conditions or mask symptoms of hypoglycemia. |
| Purpose of Taking Medication | The purpose of metoprolol therapy is to reduce blood pressure, alleviate anginal symptoms, improve cardiac function, and prevent cardiovascular events in patients with hypertension, angina pectoris, myocardial infarction, heart failure, or certain arrhythmias. Metoprolol is used as first-line therapy for the management of hypertension and may be prescribed alone or in combination with other antihypertensive agents to achieve target blood pressure goals and reduce the risk of cardiovascular complications. |
| Usage Instructions | Take metoprolol orally as directed by your healthcare provider, usually once or twice daily with or without food. Swallow the tablets whole with a full glass of water; do not crush, chew, or split the tablets unless instructed otherwise. Follow your healthcare provider’s instructions regarding dosing schedule, titration, and adjustments. |
| Precautions and Care | Patients taking metoprolol should be monitored regularly for blood pressure control, heart rate, and signs of adverse effects such as bradycardia, hypotension, dizziness, fatigue, or exacerbation of heart failure symptoms. Use caution when discontinuing metoprolol therapy, as abrupt withdrawal may precipitate rebound hypertension or exacerbate angina symptoms. Gradually taper the dose over 1-2 weeks under medical supervision if discontinuation is necessary. |
| Dietary Considerations | There are no specific dietary restrictions associated with metoprolol use, although it is important to maintain a balanced diet and limit sodium intake to help control blood pressure and reduce the risk of cardiovascular events. Avoid excessive alcohol consumption, as it may potentiate the hypotensive effects of metoprolol and increase the risk of adverse reactions. |
| Missed Dose | If a dose of metoprolol is missed, take it as soon as remembered, unless it is almost time for the next scheduled dose. Do not double the dose to make up for a missed one. Resume the regular dosing schedule and consult your healthcare provider if unsure about missed doses or medication instructions. |
| Possible Side Effects | Common side effects of metoprolol may include bradycardia, hypotension, dizziness, fatigue, headache, nausea, vomiting, diarrhea, and erectile dysfunction. Serious adverse effects may include exacerbation of heart failure, heart block, bronchospasm, depression, and masking of hypoglycemia in diabetic patients. Contact your healthcare provider if you experience severe or persistent side effects while taking metoprolol. |
| Storage and Disposal | Store metoprolol tablets at room temperature away from moisture and heat. Keep the medication out of reach of children and pets. Unused or expired medication should be disposed of properly according to local regulations or guidelines for pharmaceutical waste disposal. |
| Overdose or Emergency | In case of metoprolol overdose or emergency, seek immediate medical attention or contact a poison control center. Overdose may lead to severe bradycardia, hypotension, heart block, or cardiac arrest. Treatment of metoprolol overdose may involve supportive measures, including airway management, intravenous fluids, inotropic agents, and cardiac monitoring. |
| Monitoring and Laboratory Tests | Patients receiving metoprolol therapy require regular monitoring of blood pressure, heart rate, and signs of adverse effects, particularly during dose titration or adjustment. Additional monitoring parameters may include electrolyte levels, renal function tests, and cardiac biomarkers, depending on the clinical indication for metoprolol therapy and individual patient factors. |
