Metoprolol; Uses, Dosage, Side Effects, Interactions ,Pregnancy

Metoprolol; Uses, Dosage, Side Effects, Interactions ,Pregnancy

Metoprolol Succinate is the succinate salt form of metoprolol, a cardioselective competitive beta-1 adrenergic receptor antagonist with antihypertensive properties and devoid of intrinsic sympathomimetic activity. Metoprolol succinate antagonizes beta 1-adrenergic receptors in the myocardium, thereby reducing the rate and force of myocardial contraction, and consequently a diminished cardiac output. This agent may also reduce the secretion of renin with subsequent reduction in levels of angiotensin II thus decreasing sympathetic activation, including vasoconstriction, aldosterone secretion.

Metoprolol is a cardioselective β1-adrenergic blocking agent used for acute myocardial infarction (MI), heart failure, angina pectoris and mild to moderate hypertension. It may also be used for supraventricular and tachyarrhythmias and prophylaxis for migraine headaches. Metoprolol is structurally similar to bisoprolol, acebutolol and atenolol in that it has two substituents in the para position of the benzene ring. The β1-selectivity of these agents is thought to be due in part to the large substituents in the para position. At low doses, metoprolol selectively blocks cardiac β1-adrenergic receptors with little activity against β2-adrenergic receptors of the lungs and vascular smooth muscle. Receptor selectivity decreases with higher doses

Mechanism of Action of Metoprolol

Metoprolol competes with adrenergic neurotransmitters such as catecholamines for binding at beta(1)-adrenergic receptors in the heart. Beta(1)-receptor blockade results in a decrease in heart rate, cardiac output, and blood pressure.Metoprolol, a competitive, beta1-selective (cardioselective) adrenergic antagonist, is similar to atenolol in its moderate lipid solubility, lack of intrinsic sympathomimetic activity (ISA), and weak membrane stabilizing activity (MSA).


In patients with normal or high concentrations of circulatiing renin, low doses of metoprolol are associated with a fall in plasma renin concentrations, possibly due, at least partly, to acute peripheral beta-1-adrenergic blockade. Metoprolol also substantially reduces furosemide-induced renin release. Metoprolol and propranolol produce similar decrease in plasma renin activity in patients with high plasma renin activity. The importance of these effects in decreasing blood pressure in hypertensive patients requires further investigation.

Indications of Metoprolol

  • Angina pectoris
  • High blood pressure (Hypertension)
  • Migraines
  • Nonvalvular atrial fibrillation
  • Acute hemodynamically stable myocardial infarction
  • Atrial fibrillation
  • Supraventricular Tachycardia
  • Mitral valve prolapse
  • Angina pectoris prophylaxis
  • Benign essential tremor
  • Heart attack
  • Heart failure
  • Left ventricular dysfunction
  • Migraine prevention
  • Premature ventricular depolarizations
  • Chronic heart failure with reduced ejection fraction (NYHA Class II)
  • Chronic heart failure with reduced ejection fraction (NYHA Class III)
  • Vasovagal syncope
  • Adjunct in treatment of hyperthyroidism
  • Long QT syndrome, especially for patients with asthma, as metoprolol’s β1 selectivity tends to interfere less with asthma drugs, which are often β2-adrenergic receptor-agonist drug
  • Prevention of relapse into atrial fibrillation (controlled-release/extended-release form)
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Contra Indications of Metoprolol

Dosage of Metoprolol

Strength: 25 mg, 37.5 mg, 50 mg, 75 mg, and 100 mg; 200mg


  • Initial dose: 100 mg orally per day in single or divided doses
  • Maintenance dose: 100 to 450 mg orally per day

Angina Pectoris

  • Metoprolol tartrate immediate release tablets: 50 mg orally twice a day
  • Metoprolol succinate extended release tablets: 100 mg orally once a day
  • Maintenance dose: 100 to 400 mg per day

Myocardial infraction

  • Initial dose: 5 mg IV every 2 minutes as tolerated for 3 doses
  • Patients tolerant of full IV dose (15 mg): 50 mg orally every 6 hours starting 15 minutes after the last IV dose and continued for 48 hours
  • Patients intolerant of full IV dose (15 mg): 25 or 50 mg orally every 6 hours depending on the degree of intolerance starting 15 minutes after the last IV dose or as soon as their clinical condition allows
  • Maintenance dose: 100 mg orally twice a day

Congestive Heart Failure

  • 25 mg orally once a day (12.5 mg orally once a day in patients with more severe heart failure); double dose every 2 weeks to highest tolerated dose or up to 200 mg orally once a day

Pediatric Dose for Hypertension

  • Initial dose: 1 mg/kg orally once a day (not to exceed 50 mg orally once a day)
  • Maximum dose: 2 mg/kg (or 200 mg) orally once a day
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Side Effects of Metoprolol

The most common 



 Drugs  interactions of Metoprolol

Metoprolol may interact with following drugs, supplements, & may change the efficacy of drugs

This is not a complete list of metoprolol drug interactions. Ask your doctor or pharmacist for more information.

Pregnancy & Lactation of Metoprolol

FDA pregnancy category C


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This drug should be used during pregnancy only if clearly needed. AU and UK: Use is not recommended unless benefit outweighs risk; if used during pregnancy, administer the lowest possible dose and discontinue at least 2 to 3 days prior to expected delivery, if possible. AU TGA pregnancy category: C


This medication is found in breast milk so the patient should consult her healthcare provider if she’s going to be breastfeeding whilst taking metoprolol. If the patient is already taking metoprolol, she should not suddenly stop taking it in order to start breastfeeding without talking to her doctor first. This is because individuals who suddenly stop taking this drug may experience sharp chest pains, irregular heartbeat and sometimes even a heart attack as a result. Patients with a history of heart disease are especially at risk of these complications.





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