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Minoxidil (Systemic)

Medically reviewed by Drugs.com. Last updated on Sep 11, 2020.

Pronunciation

(mi NOKS i dil)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 2.5 mg, 10 mg

Pharmacologic Category

  • Antihypertensive
  • Vasodilator, Direct-Acting

Pharmacology

Produces vasodilation by directly relaxing arteriolar smooth muscle, with little effect on veins; effects may be mediated by cyclic AMP; stimulation of hair growth is secondary to vasodilation, increased cutaneous blood flow and stimulation of resting hair follicles

Metabolism

~90%, primarily via glucuronidation

Excretion

Urine (12% as unchanged drug)

Onset of Action

Hypotensive: ~30 minutes; Peak effect: 2 to 3 hours

Duration of Action

Up to 2 to 5 days

Half-Life Elimination

3.5 to 4.2 hours

Protein Binding

None

Use: Labeled Indications

Hypertension: Management of hypertension that is symptomatic or associated with target organ damage, and is not manageable with maximum therapeutic doses of a diuretic plus 2 other antihypertensives. Use in milder degrees of hypertension is not recommended because the benefit-risk ratio in such patients has not been defined. Note: Not recommended for the initial treatment of hypertension (ACC/AHA [Whelton 2018]).

Contraindications

Hypersensitivity to minoxidil or any component of the formulation; pheochromocytoma

Canadian labeling: Additional contraindications (not in US labeling): Pulmonary hypertension associated with mitral stenosis; severe hepatic impairment

Dosing: Adult

Hypertension (alternative agent):

Note: Reserve for patients who do not respond adequately to maximum therapeutic doses of a diuretic and 2 other antihypertensive agents. Concomitant therapy with a beta-blocker is recommended to prevent reflex tachycardia.

Oral: Initial: 5 mg once daily, increase dose gradually in intervals of ≥3 days up to a maximum dose of 100 mg/day in 1 to 3 divided doses; if rapid management of hypertension is necessary, may adjust dose every 6 hours with close monitoring; usual effective dose: 10 to 40 mg/day in 1 to 3 divided doses (ACC/AHA [Whelton 2018]; manufacturer's labeling).

Note: If supine diastolic pressure is reduced <30 mm Hg by minoxidil, administer dose once daily; if supine diastolic pressure is reduced >30 mm Hg, administer in divided doses.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Hypertension, severe; resistant to multiple drugs:

Children <12 years: Initial: 0.2 mg/kg/dose once daily; maximum initial dose: 5 mg/dose; titrate to effect, may increase daily dose by 50% to 100% every 3 days; may need to divide doses 1 to 3 times daily; usual effective dosage range: 0.25 to 1 mg/kg/day in 1 to 3 divided doses; maximum daily dose: 50 mg/day (NHLBI 2011; Park 2014); Note: In situations where rapid blood pressure management required, may increase dose every 6 hours with careful monitoring.

Children ≥12 years and Adolescents: Initial: 5 mg once daily, titrate to effect, may increase every 3 days by doubling daily dose (10 mg/day, 20 mg/day, and then 40 mg/day); may need to divide doses 1 to 3 times daily; usual effective daily dose range: 10 to 40 mg/day in 1 to 3 divided doses; maximum daily dose: 100 mg/day (NHLBI 2011; Park 2014); Note: In situations where rapid blood pressure management required, may increase dose every 6 hours with careful monitoring.

Dosage adjustment for concomitant therapy: Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

Storage

Store between 20°C and 25°C (68°F and 77°F).

Drug Interactions

Alfuzosin: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Amifostine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Amifostine. Management: When amifostine is used at chemotherapy doses, blood pressure lowering medications should be withheld for 24 hours prior to amifostine administration. If blood pressure lowering therapy cannot be withheld, amifostine should not be administered. Consider therapy modification

Amphetamines: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Antipsychotic Agents (Second Generation [Atypical]): Blood Pressure Lowering Agents may enhance the hypotensive effect of Antipsychotic Agents (Second Generation [Atypical]). Monitor therapy

Atazanavir: May increase the serum concentration of Minoxidil (Systemic). Monitor therapy

Barbiturates: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Benperidol: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Brigatinib: May diminish the antihypertensive effect of Antihypertensive Agents. Brigatinib may enhance the bradycardic effect of Antihypertensive Agents. Monitor therapy

Brimonidine (Topical): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Bromperidol: May diminish the hypotensive effect of Blood Pressure Lowering Agents. Blood Pressure Lowering Agents may enhance the hypotensive effect of Bromperidol. Avoid combination

CycloSPORINE (Systemic): May enhance the adverse/toxic effect of Minoxidil (Systemic). Severe hypertrichosis has been reported. Monitor therapy

Dapoxetine: May enhance the orthostatic hypotensive effect of Minoxidil (Systemic). Monitor therapy

Dexmethylphenidate: May diminish the therapeutic effect of Antihypertensive Agents. Monitor therapy

Diazoxide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

DULoxetine: Blood Pressure Lowering Agents may enhance the hypotensive effect of DULoxetine. Monitor therapy

Herbs (Hypertensive Properties): May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Herbs (Hypotensive Properties): May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Hypotension-Associated Agents: Blood Pressure Lowering Agents may enhance the hypotensive effect of Hypotension-Associated Agents. Monitor therapy

Levodopa-Containing Products: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa-Containing Products. Monitor therapy

Lormetazepam: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Methylphenidate: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Molsidomine: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Naftopidil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicergoline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nicorandil: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Nitroprusside: Blood Pressure Lowering Agents may enhance the hypotensive effect of Nitroprusside. Monitor therapy

Obinutuzumab: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Management: Consider temporarily withholding blood pressure lowering medications beginning 12 hours prior to obinutuzumab infusion and continuing until 1 hour after the end of the infusion. Consider therapy modification

Pentoxifylline: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Pholcodine: Blood Pressure Lowering Agents may enhance the hypotensive effect of Pholcodine. Monitor therapy

Phosphodiesterase 5 Inhibitors: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Probenecid: May increase the serum concentration of Minoxidil (Systemic). Monitor therapy

Prostacyclin Analogues: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Quinagolide: May enhance the hypotensive effect of Blood Pressure Lowering Agents. Monitor therapy

Valproate Products: May increase the serum concentration of Minoxidil (Systemic). Monitor therapy

Yohimbine: May diminish the antihypertensive effect of Antihypertensive Agents. Monitor therapy

Adverse Reactions

Frequency not always defined.

Cardiovascular: ECG changes (T-wave changes 60%), edema (reversible, 7% to 10%), pericardial effusion (occasionally with tamponade, 3%), angina pectoris, cardiac failure, pericarditis, tachycardia

Dermatologic: Hypertrichosis (80%), bullous rash (rare), skin rash, Stevens-Johnson syndrome (rare), toxic epidermal necrolysis

Endocrine & metabolic: Sodium retention, water retention, weight gain

Gastrointestinal: Nausea, vomiting

Hematologic & oncologic: Decreased hematocrit (transient, hemodilution), decreased red blood cells (transient, hemodilution), hemoglobin (transient, hemodilution), leukopenia (rare), thrombocytopenia (rare)

Hepatic: Ascites, increased serum alkaline phosphatase

Renal: Increased blood urea nitrogen (transient), increased serum creatinine (transient)

Respiratory: Pulmonary edema (Lee 2011)

<1%, postmarketing, and/or case reports: Breast tenderness (rare)

ALERT: U.S. Boxed Warning

Cardiac effects:

Minoxidil may produce serious adverse effects. It can cause pericardial effusion, occasionally progressing to tamponade, and it can exacerbate angina pectoris. Reserve for hypertensive patients who do not respond adequately to maximum therapeutic doses of a diuretic and 2 other antihypertensive agents.

In experimental animals, minoxidil caused several kinds of myocardial lesions and other adverse cardiac effects.

Appropriate use:

Administer under close supervision, usually concomitantly with therapeutic doses of a beta-adrenergic blocking agent, to prevent tachycardia and increased myocardial workload. Usually, it must be given with a diuretic, frequently one acting in the ascending limb of the loop of Henle to prevent serious fluid accumulation. When first administering minoxidil, hospitalize and monitor patients with malignant hypertension and those already receiving guanethidine to avoid too rapid or large orthostatic decreases in blood pressure.

Warnings/Precautions

Concerns related to adverse effects:

• Fluid retention: May cause salt and water retention; administer with a diuretic, preferably a loop diuretic (eg, furosemide) to prevent fluid retention and subsequent local and generalized edema. Use with extreme caution in patients with heart failure.

• Pericardial effusion/tamponade: [US Boxed Warning]: May cause pericarditis and pericardial effusion that may progress to tamponade; patients with renal impairment not on dialysis may be at higher risk. Use with caution in patients with heart failure; observe patients closely. If effusion persists, consider discontinuation of minoxidil.

• Rapid blood pressure control: Rapid control of blood pressure in patients with severe hypertension can lead to syncope, cerebrovascular accidents, MI, and/or ischemia of other special sense organs resulting in decrease or loss of vision or hearing. Patients with compromised circulation or cryoglobulinemia may also suffer ischemic episodes of the affected organs.

• Sinus tachycardia: [US Boxed Warning]: May increase oxygen demand and exacerbate angina pectoris; concomitant use with a beta-blocker (if no contraindication exists) may help reduce the effect. Use with caution in patients with ischemic heart disease.

Disease-related concerns:

• Acute myocardial infarct (MI): Avoid use for a month after acute MI as use may increase oxygen demand due to reflex tachycardia. Use with extreme caution; ensure patient is receiving a beta blocker prior to initiation.

• Heart failure: Compared to placebo minoxidil increased the frequency of clinical events, including increased need for diuretics, angina, ventricular arrhythmias, worsening heart failure and death (Franciosa 1984). In a scientific statement from the American Heart Association, minoxidil has been determined to be an agent that may exacerbate underlying myocardial dysfunction (magnitude: moderate) (AHA [Page 2016]).

• Renal impairment: Use with caution in patients with significant renal impairment; renal failure and dialysis patients may require a smaller dose. Monitor closely to prevent exacerbation of renal failure.

Special populations:

• Elderly: Use with caution in the elderly; initiate at the low end of the dosage range and monitor closely.

Other warnings/precautions:

• Appropriate use: [US Boxed Warning]: Maximum therapeutic doses of a diuretic and two other antihypertensives should be used before this drug is ever added. Should be given with a diuretic to minimize fluid gain and a beta-blocker (if no contraindications) to prevent tachycardia and increased myocardial workload. Patients with malignant hypertension and those already receiving guanethidine should be hospitalized with close medical supervision to ensure blood pressure is reducing and to prevent too rapid of a reduction in blood pressure.

Monitoring Parameters

BP, standing and sitting/supine; signs/symptoms of pericardial effusion or cardiac tamponade; signs/symptoms of angina; signs/symptoms of heart failure; fluid and electrolyte balance and body weight should be monitored. Any tests that are abnormal at the time of initiation (including, renal function tests, ECG, echocardiogram, chest x-ray) should be repeated initially every 1 to 3 months then every 6 to 12 months once stable.

The 2017 Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults (ACC/AHA [Whelton 2018]):

Confirmed hypertension and known cardiovascular disease or 10-year atherosclerotic cardiovascular disease risk ≥10%: Target BP <130/80 mm Hg is recommended.

Confirmed hypertension without markers of increased atherosclerotic cardiovascular disease risk: Target BP <130/80 mm Hg may be reasonable.

Pregnancy Risk Factor

C

Pregnancy Considerations

Adverse events were observed in some animal studies. Neonatal hypertrichosis has been reported following exposure to minoxidil during pregnancy.

Patient Education

What is this drug used for?

• It is used to treat high blood pressure.

• It may be given to you for other reasons. Talk with the doctor.

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Hair growth

• Vomiting

• Nausea

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Shortness of breath

• Chest pain

• Arm pain

• Shoulder pain

• Fast heartbeat

• Dizziness

• Passing out

• Abnormal heartbeat

• Severe or persistent heartburn

• Trouble breathing

• Trouble hearing

• Vision changes

• Weight gain

• Swelling

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.

Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.

Consumer Information Use and Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a limited summary of general information about the medicine's uses from the patient education leaflet and is not intended to be comprehensive. This limited summary does NOT include all information available about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not intended to provide medical advice, diagnosis or treatment and does not replace information you receive from the healthcare provider. For a more detailed summary of information about the risks and benefits of using this medicine, please speak with your healthcare provider and review the entire patient education leaflet.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.