MINAX

What it is

MINAX contains metoprolol tartrate 50 mg or 100 mg in film coated tablets. Metoprolol is a relatively cardioselective beta-blocker that acts on beta₁-receptors mainly located in the heart at lower doses than those needed to influence the beta₂-receptors mainly located in the bronchi and peripheral vessels.

Approved indications

— Hypertension: as monotherapy or for use in combination with other antihypertensives. — Angina pectoris: for long-term prophylaxis. — Confirmed or suspected myocardial infarction. — Prevention of migraine.

Dosing overview

The maximum daily dose should not exceed 400 mg. Although twice daily dosage is optimal, in those patients whose maintenance dosage is 150 mg daily or less, it may be administered as a single dose. MINAX tablets should always be taken in standard relation to meals; for example, if it is decided that the patient should take MINAX tablets with breakfast, the patient should continue to take it with breakfast throughout the course of therapy.

Key safety warnings

Beta-adrenergic blockade of the smooth muscle of bronchi and bronchioles may result in an increased airways resistance and reduce the effectiveness of asthma treatment, which may be dangerous in susceptible patients; therefore, beta-blockers are contraindicated in any patient with a history of airways obstruction or a tendency to bronchospasm. Beta-blockade depresses myocardial contractility and may precipitate cardiac failure in some patients with a history of cardiac failure, chronic myocardial insufficiency or unsuspected cardiomyopathy, and in patients without a history of cardiac failure, continuing depression of the myocardium may lead to cardiac failure. There is a risk of exacerbating the number and duration of coronary artery spasms if patients with Prinzmetal angina or variant angina pectoris are treated with MINAX; if this treatment is essential, it should only be undertaken in a Coronary or Intensive Care Unit. MINAX should be used with caution in patients with diabetes mellitus, especially those receiving insulin or oral hypoglycaemic agents, as beta-blockers affect glucose metabolism and may mask some important premonitory signs of acute hypoglycaemia, such as tachycardia. Care should be taken if beta-blockers have to be discontinued abruptly in patients with coronary artery disease, as severe exacerbation of angina and precipitation of myocardial infarction and ventricular arrhythmias have occurred following abrupt discontinuation; therefore, it is recommended that the dosage be reduced gradually over a period of about 8–14 days.

Contraindications

MINAX is contraindicated in patients with known hypersensitivity to metoprolol and related derivatives, hypersensitivity to any of the excipients, sensitivity to other beta-blockers (cross-sensitivity between beta-blockers can occur), atrioventricular block of second or third degree, congestive heart failure, sinus bradycardia (less than 45 to 50 beats per minute), sick-sinus syndrome, severe peripheral arterial circulatory disorders, shock (including cardiogenic and hypovolaemic shock), myocardial infarction patients with a heart rate of less than 45 beats per minute, a P-R interval of greater than 0.24 seconds, a systolic blood pressure of less than 100 mmHg, and/or moderate to severe heart failure, right ventricular failure secondary to pulmonary hypertension, significant right ventricular hypertrophy, hypotension, untreated phaeochromocytoma, allergic disorders (including allergic rhinitis) which may suggest a predisposition to bronchospasm, and severe bronchial asthma or history of severe bronchospasm.

Regulatory history

MINAX metoprolol tartrate 50 mg and 100 mg tablets in bottle form were first registered on the ARTG on 24 December 1991. Tablet blister pack formulations of MINAX 50 mg and 100 mg metoprolol tartrate were first listed on the ARTG on 23 November 1992. MINAX XL modified release formulations containing metoprolol succinate 23.75 mg, 47.5 mg, 95 mg, and 190 mg were first listed on the ARTG on 9 April 2014.