Minoxidil

Minoxidil is an antihypertensive vasodilator medication and is used to treat hair loss. It is available as a generic medication and over the counter for the treatment of androgenic alopecia, a form of hair loss, in people.

Molecular Structure

Minoxidil

Class of Drug

Antihypertensive, vasodilator, hair growth stimulator.

Mechanism of Action

Causes arteriolar smooth muscle relaxation, resulting in decreased BP, increased peripheral resistance. Stimulates hair follicles by increasing blood flow to skin.

Indications / Dosage / Route

Routes of Administration: Oral, topical..

Condition: Hypertension (combination, usually with diuretic and (β blocker)

Dose: Adults, children >12 years: Initial: PO 5 mg/d. Slowly increase dose q3d to optimum BP response. Maintenance: 10-40 mg/d. Maximum: 100 mg/d.

         Children: <12 years: 0.1-0.2 mg/kg/d as single dose (maximum: 5 mg). Gradually increase q3d to 0.25-1 mg/kg/d in single or divided doses (maximum 50 mg/d).

Condition: Topical male and female pattern baldness

Dose:  1 ml (2 or 5% solution) bid to area with loss of hair

Adjustment of Dosage

Kidney disease: Reduce dose by one-third usual in renal failure.

Liver disease: None.

Elderly: Initial dose reduced to 2.5 mg daily. Slow dosage increases.

PediatricSee above.

Onset of Action Peak Effect Duration
30 min 2-3 h 2-5 d

Food and Drug Interactions

FoodMay be taken with or without food.

Pregnancy: Category C.

LactationAppears in breast milk. Potentially toxic to infant. Avoid breastfeeding.

Contraindications: Hypersensitivity to minoxidil, pheochromocytoma, MI (within 1 month), dissecting aortic aneurysm.

Warnings / Precautions

> Use with caution in patients with coronary artery disease, renal disease(severe), pulmonary hypertension, CHF.

> Prior to discontinuation, consult treating physician.

> To minimize possible photosensitivity reaction, apply adequate sunscreen and use proper covering when exposed to strong sunlight.

Clinically Important Drug Interactions

> Drugs that increase effects/toxicity of minoxidil: guanethidine, diuretics, other antihypertensives.

> Drugs that decrease effects/toxicity of minoxidil: NSAIDs.

Adverse Reactions

> Common: Edema, tachycardia, breast tenderness, weight gain, hypertrichosis.

> Serious: predisposition to CHF, pericardial effusion, Stevens Johnson syndrome, fluid and electrolyte disturbance, angina, bone marrow suppression.

Parameters to Monitor

> BP and pulse for orthostasis, checking supine, seated, and standing BPs. Significant changes, eg, heart rate increase >20 beats/min, probably require reduction of dosage.

> Intake of fluids and urinary and other fluid output to minimize renal toxicity. Closely monitor electrolyte levels.

> Signs of CHF.

> Signs and symptoms of Stevens-Johnson syndrome.

Advice to Patient

> Do not take magnesium-containing antacids.

Further Useful Info

> Minoxidil should be given along with a diuretic unless the patient is on hemodialysis.

> Use should be limited to those patients who do not respond to maximum doses of diuretics and to other antihypertensive agents.

> Minoxidil should be administered under close supervision by the treating physician.

> A P blocker is generally given concomitantly to prevent tachycardia.

> Oral and topical forms of minoxidil have been used to treat male pattern baldness. Minoxidil stimulates resting hair follicles and increases cutaneous blood flow via its vasodilatory properties.

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