Clinical Pharmacology Details


METOPROLOL


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Indications & Dose:

Hypertension 



Adult: Initially 100 mg daily, increased if necessary to 200 mg daily in 1–2 divided doses, high doses are rarely required; maximum 400 mg per day



Adult: 200 mg once daily


Angina 



Adult: 50–100 mg 2–3 times a day



Adult: 200–400 mg daily continued


Arrhythmias



Adult: Usual dose 50 mg 2–3 times a day, then increased if necessary up to 300 mg daily in divided doses



Adult: Up to 5 mg, dose to be given at a rate of 1–2 mg/minute, then up to 5 mg after 5 minutes if required, total dose of 10–15 mg


Migraine prophylaxis



Adult: 100–200 mg daily in divided doses



Adult: 200 mg daily


Hyperthyroidism (adjunct) 



Adult: 50 mg 4 times a day


In surgery 



Adult: Initially 2–4 mg, given at induction or to control arrhythmias developing during anaesthesia, then 2 mg, repeated if necessary; maximum 10 mg per course Early intervention within 12 hours of infarction 



Adult: Initially 5 mg every 2 minutes, to a max. of 15 mg, followed by (by mouth) 50 mg every 6 hours for 48 hours, to be taken 15 minutes after intravenous injection; (by mouth) maintenance 200 mg daily in divided doses.


Children: 1-5mg/kg/24 hrs. divided every 12 hrs


 


 

Contraindications:

Bronchial asthma, cardiogenic shock overt cardiac failure, 2nd and 3rd degree AV block, severe sinus bradycardia 

Side Effects:

CNS: Confusion, depression, dizziness, fatigue, headache, insomnia, memory loss, strange dreams


CV: Bradycardia, CHF, cold extremities, heart block, hypotension


EENT: Tinnitus, visual disturbances


GI: Constipation, diarrhea, dry mouth, heart burn, nausea


GU: Impotence, sexual dysfunction


HEME: Agranulocytosis (rare)


METAB: Hyperlipidemia (increased TG, total cholesterol, LDL; decreased HDL); masked hypoglycemic response to insulin(sweating excepted)


RESP: Bronchospasm (1%), dyspnea


SKIN: Alopecia, pruritus, rash


 

Cautions:

Precautions:

Anesthesia/surgery (myocardial depression); avoid abrupt withdrawal, bronchospastic airways, congestive heart failure,diabetes mellitus, hyperthyroidism/ thyrotoxicosis,concurrent clonidine (discontinue atenolol several days prior to withdrawal of clonidine), peripheral vascular disease, renal disease,


Pregnancy & breast-feeding: Use with caution.


Old age: May be used.


 

Interaction:

Drugs


a-adrenergic blockers: Potential enhanced first dose response (marked initial drop in blood pressure) particularly on standing (especially prazocin)Amiodarone: Bradycardia, cardiac arrest, or ventricular dysrhythmia


Antidiabetic: Altered response to hypoglycemia, prolonged recovery of normoglycemia, hypertension, blockade of tachycardia; may increase blood glucose and impair peripheral circulation


Antipyrine: Increased antipyrine concentrations


Barbiturates: Reduced ß-blocker concentrations


Beta agonists: Antagonism of bronchodilating effect Bromazepam, diazepam, oxazepam: increased benzodiazepine effect, (lorazepam and alprazolam unaffected)


Cimetidine, etintidine, propafenone, propoxyphene, quinidine: Increased plasma metoprolol concentration


Clonidine: Abrupt withdrawal of clonidine while ona (ß-blocker may exaggerate the rebound hypertension due to unopposed oc stimulation


Digoxin: Additive prolongation of atrioventricular (AV) conduction time


Dihydropyridines (nicardipine, nifedipine, felodipine, isradipine, nisoldipine): Increased beta blocker effects


Diltiazem: Potentiates ß-adrenergic effects; hypotension, left ventricular failure, and AV conduction disturbances problematic in elderly, patients with left ventricular dysfunction, aortic stenosis, or with large doses of either drug Dipyridamole,


Tacrine: Bradycardia


Fluoxetine: Enhanced effect of ß-blocker Hypoglycemic agents,: Masked hypoglycemia, hyperglycemia


Isoproterenol: Potential reduction in effectiveness of isoproterenol in the treatment of. asthma; less likely with cardioselective agents like metoprolol


Local anesthetics: Use of local anesthetics containing epinephrine may result in hypertensive reactions in patients taking P-blockers


NSAIDs: Reduced hypotensive effects of ß-blockers


Phenylephrine: Enhanced pressor response to phenylephrine, particularly when it is administered


Prazosin: First-dose response to prazosin may be enhanced by blockade


Quinolones: Inhibition of ß-blocker metabolism, increased ß-blocker effects


Rifampin: Reduced plasma metoprolol concentration


Theophylline: Antagonistic pharmacodynamic effects


Verapamil: Potentiates ß-adrenergic effects; hypotension, left ventricular failure, and AV conduction disturbances problemmatic in elderly, patients with left ventricular dysfunction, aortic stenosis, or with large doses of either drug


 


 

Warnings:

Adverse Effects:

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Counselling:

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Patient And Carer Advice: