Antihypertensive - Anti-anginal
Pharmacology: Metoprolol is a beta-adrenergic-receptorblocking agent. In vitro and in vivo animal studies have shown that it has a preferential effect on beta1-adrenoreceptors, chiefly located in cardiac muscle. This preferential effect is not absolute, however, and at higher doses, metoprolol also inhibits beta2-adrenoreceptors, chiefly located in the bronchial and vascular musculature. It is used in the treatment of hypertension, angina pectoris and to reduce mortality in patients with myocardial infarction.
Indications: Hypertension: Metoprolol is indicated in patients with mild or moderate hypertension. It is usually used in combination with other drugs, particularly a thiazide diuretic. However, it may be tried alone as an initial in those patients in whom, in the judgment of the physician, treatment should be started with a beta-blocker rather than a diuretic.
Contraindications: sinus bradycardia; second and third degree AV block; right ventricular failure secondary to pulmonary hypertension; congestive heart failure; cardiogenic shock; anesthesia with agents that produce myocardial depression, e.g. ether.
Warnings: Cardiac failure: Special caution should be exercised when administering metoprolol to patients with a history of heart failure.
Precautions: Patients with bronchospastic diseases should, in general, not receive beta-blockers. Because of its relative beta1-selectivity, however, metoprolol may be used with caution in patients with bronchospastic disease who do not respond to,or cannot tolerate, other antihypertensive treatment.
Adverse Effects: The most common adverse reactions reported are exertional tiredness, gastrointestinal disorders and disturbances of sleep patterns. The most serious adverse reactions reported are congestive heart failure, bronchospasm and hypotension.
Dosage: Hypertension: Metoprolol is usually used in conjunction with other antihypertensive agents, particularly a thiazide diuretic, but may be used alone (see Indications).
Adjust dosage to patient’s individual requirements in accordance with the following guidelines.
Initial dosage is 50 mg twice daily. However, if an adequate response is not seen after 1 week, dosage should be increased to 100 mg twice daily. In some cases the daily dosage may need to be increased by further 100 mg increments at intervals of not less than 2 weeks up to a maximum of 200 mg twice daily, which should not be exceeded. The usual maintenance dose is within the range of 100 to 200 mg daily.
When metoprolol is combined with another antihypertensive agent which is already being administered, metoprolol should be added initially at a dose of 50 mg twice daily. After 1 or 2 weeks the daily dosage may be increased if required, in increments of 100 mg, at intervals of not less than 2 weeks, until adequate blood pressure control is obtained.
Angina pectoris: The recommended dosage range is 100 to 400 mg/day in divided doses. Initiate treatment with 50 mg twice daily for the first week. If the response is inadequate, increase the daily dosage by 100 mg for the next week. The usual maintenance dose is 200 mg/day. The need for further increases should be closely monitored at weekly intervals and the dosage increased in 100 mg increments to a maximum of 400 mg/day in 2 or 3 divided doses.
A metoprolol dose of 400 mg/day should not be exceeded.
Supplied: Tablets: Each compressed, white, scored, biconvex, circular tablet, contains: metoprolol tartrate 50 mg. Also contains lactose, sodium starch, cellulose, polyvinyl pyrrolidone, colloidal silica, glycolate and magnesium stearate. Energy: 0.31 kJ (0.07 kcal). Gluten- and tartrazine-free. Bottles of 100 and 500.Injection: Each mL of aqueous injectable solution contains: metoprolol tartrate 1 mg. Also contains sodium chloride 45 mg (9 mg/mL). Glass vials of 5 mL.