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).
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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)
Contra Indications of Metoprolol
- Pheochromocytoma
- Diabetes
- Low blood sugar
- depression
- Myasthenia Gravis
- Complete Heart Block
- Second Degree Atrioventricular Heart Block
- Sick Sinus Syndrome
- Sinus Bradycardia
- Suddenly serious symptoms of heart failure
- Occasional Numbness
- or Tingling of Fingers and Toes
- Peripheral Vascular Disease
- abnormally low blood pressure
- Asthma Attack
- Bronchospasm
- Liver problems
- Psoriasis
- Blood Circulation Failure due to Serious Heart Condition
- Anaphylactic Shock due to Allergy Shots
- peripheral arterial occlusive disease
- First Degree Atrioventricular Heart Block
Dosage of Metoprolol
Strength: 25 mg, 37.5 mg, 50 mg, 75 mg, and 100 mg; 200mg
Hypertenson
- 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
Side Effects of Metoprolol
The most common
- Dry cough
- Depression
- Dizziness and light-headedness due to low blood pressure
- Fatigue, especially in the early stages
- Mouth dryness in the early stages
- The most commonrn (a burning feeling in the chest, behind the breastbone or gullet)
- Abdominal or stomach pain
- Constipation
- High blood pressure
- Nausea ,vomiting,
- painful or swollen gums
- numbness or heavy feeling in the jaw
- dull, aching pain in the hip, groin, or thigh
- stomach pain,
- headache,
- reversible hair loss or thinning, and
- fever.
Common
- chills or fever
- headache, severe and throbbing
- joint or back pain
- muscle aching or cramping
- muscle pains or stiffness
- chest pressure or squeezing pain in chest
- excessive sweating
- sudden drowsiness or need to sleep
- coughing up blood
- liver problems–nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes)
- decreased amount of urine
Rare
- Anxiety
- change in vision
- chest pain or tightness
- confusion
- cough
- Agitation
- arm, back, or jaw pain
- blurred vision
- chest pain or discomfort
- convulsions
- extra heartbeats
- hallucinations
- headache
- irritability
- lightheadedness
- cold and clammy skin
- fast and shallow breathing
- swelling of your feet, legs, or hands purple spot on your skin caused by internal bleeding
- fast or abnormal heart rate or palpitations
- loss of appetite
- lower back, side, or stomach pain
- mental depression
- muscle pain or cramps
Drugs interactions of Metoprolol
Metoprolol may interact with following drugs, supplements, & may change the efficacy of drugs
- antidiabetes medications (e.g., insulin, metformin, gliclazide)
- beta-2 agonists (e.g., formoterol, salmeterol, salbutamol)
- bosutinib
- bupropion
- calcium channel blocking agents (e.g., diltiazem, verapamil)
- cimetidine
- cyclosporine
- fluoxetine
- MAO inhibitors (e.g., phenelzine, tranylcypromine)
- medications that affect heart rhythm
- medications that lower blood pressure
- nitroglycerin
- paroxetine
- rituximab
- tricyclic antidepressants (e.g., amitriptyline, nortriptyline)
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
Pregnancy
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
Lactation
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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