Drug information of Metoprolol
Mechanism of effect
Metoprolol is a beta1-selective (cardioselective) adrenergic receptor blocker. This preferential effect is not absolute, however, and at higher plasma concentrations, Metoprolol also inhibits beta2 adrenoreceptors, chiefly located in the bronchial and vascular musculature.
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)
Absorption is Rapid and complete, 50%. Metoprolol is extensively distributed with a reported volume of distribution of 3.2 to 5.6 L/kg. About 10% of Metoprolol in plasma is bound to serum albumin Metoprolol is primarily metabolized by CYP2D6 Elimination of Metoprolol is mainly by biotransformation in the liver. The mean elimination half-life of Metoprolol is 3 to 4 hours
--Usual Adult Dose for Angina Pectoris Prophylaxis Initial dose: 100 mg orally in 1 or 2 divided doses. Maintenance dose: 100 to 450 mg/day. Extended release may be used at the same total daily dose given once a day. --Usual Adult Dose for Hypertension Initial dose: 100 mg orally in 1 or 2 divided doses. Maintenance dose: 100 to 450 mg/day. Extended release may be used at the same total daily dose given once a day
Drug contraindicationshypersensitivity to drug or its components. , sinus bradycardia , greater than first-degree block , cardiogenic shock , overt cardiac failure , heart failure , systolic blood pressure < 100 mmHg
Side effectsHeadache , insomnia , dizziness , vomiting , allergic reaction , rash , Bradycardia , Depression , Diarrhea , Dyspnea , pruritus , Hypertension , confusion , bronchospasm , Angina pectoris
InteractionsUrtidin , Ipratropium bromide , Imatinib , Propyl thiouracil , Theophyline , Tadalafil , Drospirenone , Digoxin , Cinacalcet , Fingolimod , Gadopentetate dimeglumine , Gadodiamide , Ibuprofen , Indomethacin , Paroxetine , Piroxicam , Dihydroergotamine , Diltiazem , Verapamil , Fluoxetine , Phenobarbital , Gliclazide , Lidocaine , Hydralazine , Repaglinide , Salbutamol , Salmeterol , Cimetidine , Sertraline , Citalopram , Methimazole , Clozapine , Yohimbine , Insulin glargine , Bisoprolol , ritodrine , escitalopram , Quetiapine , Glipizide , Dimethyl Fumarate , Doxazosin , Dolasetron , Polyethylene glycol , Peginterferon alfa-2b , Penbutolol , lipiodol , Nebivolol , ProHance , Treprostinil , Metipranolol , Methyclothiazide , Naltrexone and Bupropion , Oxtriphylline , Florbetapir F18
1-Beta-blockers, like Metoprolol, can cause depression of myocardial contractility and may precipitate heart failure and cardiogenic shock. If signs or symptoms of heart failure develop, treat the patient according to recommended guidelines. It may be necessary to lower the dose of Metoprolol or to discontinue it 2-Do not abruptly discontinue Metoprolol therapy in patients with coronary artery disease. Severe exacerbation of angina, myocardial infarction and ventricular arrhythmias have been reported in patients with coronary artery disease following the abrupt discontinuation of therapy with beta-blockers 3-Chronically administered beta-blocking therapy should not be routinely withdrawn prior to major surgery; however, the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures 4-Bradycardia, including sinus pause, heart block and cardiac arrest have occurred with the use of Metoprolol. Patients with first-degree atrioventricular block, sinus node dysfunction or conduction disorders may be at increased risk. Monitor heart rate and rhythm in patients receiving Metoprolol. If severe bradycardia develops, reduce or stop Metoprolol 5-Patients with bronchospastic disease, should, in general, not receive beta-blockers, including Metoprolol 6-Beta-blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected 7-If Metoprolol is used in the setting of pheochromocytoma, it should be given in combination with an alpha-blocker, and only after the alpha-blocker has been initiated. Administration of beta-blockers alone in the setting of pheochromocytoma has been associated with a paradoxical increase in blood pressure due to the attenuation of beta-mediated vasodilatation in skeletal muscle 8-Metoprolol may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Avoid abrupt withdrawal of beta-blockade, which might precipitate a thyroid storm
Points of recommendation
1-Advise patients to take Metoprolol regularly and continuously, as directed, with or immediately following meals. If a dose should be missed, the patient should take only the next scheduled dose (without doubling it). Patients should not discontinue Metoprolol without consulting the physician. 2-Advise patients (1) to avoid operating automobiles and machinery or engaging in other tasks requiring alertness until the patient’s response to therapy with Metoprolol has been determined; (2) to contact the physician if any difficulty in breathing occurs; (3) to inform the physician or dentist before any type of surgery that he or she is taking Metoprolol.