Minoxidil

Because of the potential for serious adverse effects, minoxidil tablets are indicated only in the treatment of hypertension that is symptomatic or associated with target organ damage and is not manageable with maximum therapeutic doses of a diuretic plus two other antihypertensive drugs. At the present time use in milder degrees of hypertension is not recommended because the benefit-risk relationship in such patients has not been defined. Minoxidil reduced supine diastolic blood pressure by 20 mmHg or to 90 mmHg or less in approximately 75% of patients, most of who had hypertension that could not be controlled by other drugs.

Patients over 12 years of age: The recommended initial dosage of minoxidil tablets is 5 mg given as a single daily dose. Daily dosage can be increased to 10 mg, 20 mg and then to 40 mg in single or divided doses if required for optimum blood pressure control. The effective dosage range is usually 10 to 40 mg per day. The maximum recommended dosage is 100 mg per day. Patients under 12 years of age: The initial dosage is 0.2 mg/kg minoxidil as a single daily dose. The dosage may be increased in 50 to 100% increments until optimum blood pressure control is achieved. The effective dosage range is usually 0.25 to 1.0 mg/kg/day. The maximum recommended dosage is 50 mg daily. Dose frequency: The magnitude of within-day fluctuation of arterial pressure during therapy with minoxidil is directly proportional to the extent of pressure reduction.

Minoxidil tablets are contraindicated in pheochromocytoma, because it may stimulate secretion of catecholamines from the tumor through its antihypertensive action. Minoxidil is contraindicated in those patients with a history of hypersensitivity to any of the components of the preparation.

Minoxidil tablets contain the powerful antihypertensive agent, minoxidil, which may produce serious adverse effects. It can cause pericardial effusion, occasionally progressing to tamponade, and angina pectoris may be exacerbated. Minoxidil should be reserved for hypertensive patients who do not respond adequately to maximum therapeutic doses of a diuretic and two other antihypertensive agents. 1. Salt and Water Retention: Congestive Heart Failure - concomitant use of an adequate diuretic is required - Minoxidil tablets must usually be administered concomitantly with a diuretic adequate to prevent fluid retention and possible congestive heart failure, a high ceiling (loop) diuretic is almost always required. Body weight should be monitored closely.

1. Salt and Water Retention - Temporary edema developed in 7% of patients who were not edematous at the start of therapy. 2. Pericarditis, Pericardial Effusion and Tamponade. 3. Dermatologic - Hypertrichosis-Elongation, thickening, and enhanced pigmentation of fine body hair are seen in about 80% of patients taking minoxidil tablets. This develops within 3 to 6 weeks after starting therapy. It is usually first noticed on the temples, between the eyebrows, between the hairline and the eyebrows, or in the side-burn area of the upper lateral cheek, later extending to the back, arms, legs, and scalp. Upon discontinuation of minoxidil, new hair growth stops, but 1 to 6 months may be required for restoration to pretreatment appearance. No endocrine abnormalities have been found to explain the abnormal hair growth, thus, it is hypertrichosis without virilism.

4. Drug Interactions See “Interaction with Guanethidine” under WARNINGS.

Store at controlled room temperature 20° to 25°C (68° to 77°F).