Betaone

Metoprolol is a selective beta1-blocker. Metoprolol reduces or inhibits the agonistic effect on the heart of catecholamines (which are released during physical and mental stress). This means that the usual increase in heart rate, cardiac output, cardiac contractility and blood pressure, produced by the acute increase in catecholamines, is reduced by Metoprolol. Metoprolol interferes less with Insulin release and carbohydrate metabolism than do non-selective beta-blockers. Metoprolol interferes much less with the cardiovascular response to hypoglycaemia than do non-selective beta-blockers.

Catecholamine‐depleting drugs (e.g. Reserpine, Monoamine Oxidase (MAO) inhibitors) may have an additive effect when given with beta‐blocking agents. Drugs that inhibit CYP2D6 such as quinidine, fluoxetine, paroxetine and propafenone are likely to increase Metoprolol concentration. These increases in plasma concentration would decrease the cardioselectivity of Metoprolol. Concomitant use of digitalis glycosides and beta‐blockers can increase the risk of bradycardia. Beta‐blockers may exacerbate the rebound hypertension which can follow the withdrawal of clonidine.

Tiredness, dizziness, depression, diarrhea, itching or rash, shortness of breath, slow heart rate, mental confusion, headache, somnolence, nightmares, insomnia, dyspnea, Nausea, dry mouth, gastric pain, constipation, flatulence, digestive tract disorders, heartburn, pruritus, musculoskeletal pain, blurred vision, decreased libido, and tinnitus have also been reported, intensification of AV block.

Pregnancy Category C. There are no adequate and well‐controlled studies in pregnant women. This drug should be used during pregnancy only if clearly needed. Metoprolol is excreted in breast milk in very small quantities. Caution should be exercised when Metoprolol is administered to a nursing woman.

Bronchospastic Diseases: Because of its relative beta 1 ‐selectivity, however, Metoprolol may be used with caution in patients with bronchospastic disease who do not respond to, or cannot tolerate other antihypertensive treatment.

Major Surgery: The necessity or desirability of withdrawing beta‐blocking therapy prior to major surgery is controversial; the impaired ability of the heart to respond to reflex adrenergic stimuli may augment the risks of general anesthesia and surgical procedures.

Diabetes and Hypoglycemia: Beta‐blockers may mask tachycardia occurring with hypoglycemia, but other manifestations such as dizziness and sweating may not be significantly affected. Peripheral Vascular Disease: Beta‐blockers can precipitate or aggravate symptoms of arterial insufficiency in patients with peripheral vascular disease. Calcium Channel Blockers: Because of significant inotropic and chronotropic effects in patients, caution should be exercised in patients treated with these agents concomitantly.

Hepatic impaired patient: Metoprolol should be used with caution in patients with impaired hepatic function.

Pediatric Use: No clinically relevant differences in the adverse event profile were observed for pediatric patients aged 6 to 16 years as compared with adult patients. Safety and effectiveness of Metoprolol have not been established in patients <6 years of age.

Geriatric Use: There were no notable differences in efficacy or the rate of adverse events between older and younger patients.

Poisoning due to an overdose of metoprolol may lead to severe hypotension, sinus bradycardia, atrioventricular block, heart failure, cardiogenic shock, cardiac arrest, bronchospasm, impairment of consciousness, coma, nausea, vomiting, cyanosis, hypoglycaemia and, occasionally, hyperkalaemia. The first manifestations usually appear 20 minutes to 2 hours after drug ingestion. Treatment: Treatment should include close monitoring of cardiovascular, respiratory and renal function, and blood glucose and electrolytes. Further absorption may be prevented by induction of vomiting, gastric lavage or administration of activated-charcoal if ingestion is recent. Cardiovascular complications should be treated symptomatically, which may require the use of sympathomimetic agents (e.g. noradrenaline, metaramionl), atropine or inotropic agents (e.g. dopamine, dobutamine). Temporary pacing may be required for AV block. Glucagon can reverse the effects of excessive B-blockade, given in a dose of 1-10 mg intravenously. Intravenous B2-stimulants e.g. terbutaline may be required to relieve bronchospasm. Metoprolol cannot be effectively removed by haemodialysis.

Store in a cool and dry place, protected from light.