Minoxidil

Registered South African indications:

• Refractory hypertension - severe

Contraindications

Registered South African contraindications

• Hypersensitivity to minoxidil or to any of the excipients
• Pulmonary hypertension associated with mitral stenosis
• Phaeochromocytoma because it may stimulate secretion of catecholamines from the tumour through its antihypertensive action
• Pregnancy
• Lactation
• Severe liver impairment

Contraindications registered in other jurisdictions

• Hypersensitivity to the active ingredient of any of its excipients
• Phaeochromocytoma because it may stimulate secretion of catecholamines from the tumour through its antihypertensive action

Cautions

• Pregnancy (Recommendations in other jurisdictions)
• Breastfeeding (Recommendations in other jurisdictions)
• Renal impairment
• Mild to moderate hepatic impairment (South African recommendations)
• Hepatic impairment (Recommendations in other jurisdictions)
• Elderly
• Recent myocardial infarction
• Galactose intolerance
• Lapp lactose deficiency 
• Glucose-galactose malabsorption 

Forms avail. in SA and covered in this monograph: tab

Dosages below include:

• South African registered indications and dosages

South African registered indications and dosages

Refractory hypertension - severe (Additional agents required)
- As adjunctive therapy in patients who have failed to respond to extensive multiple therapy

• Oral (tab): Initial: 5-40mg/day, as a single or divided daily dosage; If the desired reduction in diastolic pressure is greater than 30mmHg, divided dosage will minimize diurnal fluctuations; Dosage adjustments should be made at intervals of 3 days or longer; A more rapid reduction of pressure can be achieved using continuous blood pressure monitoring and incremental doses of 5mg every 6hrs; Dosage requirements may be lower in patients undergoing chronic dialysis; Max: 100mg/24hrs

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Minoxidil should be used concurrently with a sympathetic nervous system suppressant and a diuretic to initiate therapy. When other sympathetic nervous system suppressants are used, the initial dosage of minoxidil should be reduced. See additional prescribing points for concomitant therapy

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Prior to introducing minoxidil, it is recommended that the antihypertensive therapy be adjusted to a regimen consisting of a diuretic and beta-adrenergic blocking medicine

Paed. forms avail. in SA and covered in this monograph: tab

Paed. dosages below include:

• South African registered indications and dosages

South African registered indications and dosages

Refractory hypertension - severe (Additional agents required)
- As adjunctive therapy in patients who have failed to respond to extensive multiple therapy

Younger than 12 years

• No specific recommendations have been provided

Older than 12 years

• Oral (tab): Initial: 5mg as a single or divided daily dosage; Incremental increases: 5-10mg/day, at 3-day intervals, until 50mg/day is reached; Then in increments of 25mg/day; Max: 100mg/24hrs

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Minoxidil should be used concurrently with a sympathetic nervous system suppressant and a diuretic to initiate therapy. When other sympathetic nervous system suppressants are used, the initial dosage of minoxidil should be reduced. See additional prescribing points for concomitant therapy

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Prior to introducing minoxidil, it is recommended that the antihypertensive therapy be adjusted to a regimen consisting of a diuretic and beta-adrenergic blocking medicine

Pregnancy

South African recommendations

• Contraindicated
• Minoxidil is contraindicated during pregnancy and in women of childbearing potential not using contraception
• There is limited data from the use of minoxidil in pregnant women. Studies in animals have shown reproductive toxicity

Recommendations in other jurisdictions

• Caution; not recommended
• There is limited data from the use of minoxidil in pregnant women. Studies in animals have shown reproductive toxicity
• Minoxidil is not recommended during pregnancy and in women of childbearing potential not using contraception. Neonatal hirsutism has been reported following exposure of minoxidil during pregnancy

Breastfeeding

South African recommendations

• Contraindicated
• Minoxidil has been reported to be excreted in human milk. A risk to the suckling child cannot be excluded. Minoxidil should not be used by women who are breastfeeding their babies

Recommendations in other jurisdictions

• Caution, not recommended
• Minoxidil has been reported to be excreted in human milk. A risk to the suckling child cannot be excluded. A decision must be made whether to discontinue breastfeeding or to discontinue/abstain from minoxidil therapy taking into account the benefit of breastfeeding for the child and the benefit of therapy for the woman

Fertility

South African recommendations

• No information available

Recommendations in other jurisdictions

• There are no fertility data from the use of minoxidil in humans. In a fertility study with male and female rats, a dose-dependent reduction of the conception rate was found. The dose corresponded to one to five times the maximum dose used in humans to treat hypertension

Renal Impairment

• Caution; dose adjustment recommended
  Dosage requirements may be lower in dialysis patients

Hepatic Impairment

South African recommendations

• Mild to moderate: Caution; dose adjustment recommended
  For patients with hepatic impairment, dosage adjustment should be considered, starting therapy at a reduced dose once daily and titrating up to the lowest effective dose to obtain desired therapeutic effect
• Severe: Contraindicated

Recommendations in other jurisdictions

• Caution; no information available

Elderly

• Caution; dose adjustment recommended 
  Initial: 2.5mg, daily; titrate gradually

Porphyria Information

• Not yet classified (NC)

Drugs in Sport

• Permitted - No warnings 

Cardiovascular Disorders

• Tachycardia 
• Pericarditis
• Pericardial effusion 
• Cardiac tamponade
• Angina pectoris

Respiratory Disorders

• Pleural effusion

Genitourinary Disorders

• Breast tenderness

Endocrine and Metabolic Disorders

• Fluid retention
• Oedema

Skin and Subcutaneous Tissue Disorders

• Hypertrichosis
• Hair colour changes
• Stevens-Johnson syndrome
• Dermatitis
• Bullous rash

Immune, Blood and Lymphatic System Disorders

• Leucopaenia
• Thrombocytopaenia

• Antihypertensives
• Sympathetic-blocking agents

• Renal function
• Electrolytes
• Weight

Concomitant therapy

• Diuretics: Minoxidil must be given with sufficient diuretic therapy to maintain salt and water balance in all patients who are on dialysis. When excessive water retention results in a weight gain exceeding 2kg, the type of diuretic should be changed or an aldosterone antagonist should be added. In children, diuretic dosage should be proportional to body weight
• Sympathetic nervous system suppressants: Initially, most patients will require a sympathetic nervous system suppressant to limit a minoxidil-induced rise in heart rate. The preferred medicine is a beta-blocker equivalent to an adult propranolol dosage of 80-160mg/day. Higher doses may be required when pre-treated patients have an increase in heart rate exceeding 20 beats/minute or when simultaneous introduction causes an increase exceeding 10 beats/minute. When beta-blockers are contraindicated, methyldopa or clonidine may be used instead and should be started 24 hours prior to minoxidil

Minoxidil lowers systolic and diastolic blood pressure by decreasing peripheral vascular resistance via vasodilation. It activates the ATP-modulated potassium channel causing potassium efflux, hyperpolarization, and smooth muscle relaxation.

Tablet 5mg

• Loniten (Pfizer) originator

Tablet 10mg

• Loniten (Pfizer) originator