Skip to Content

Minoxidil (Systemic)

Pronunciation

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: Treatment 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: According to the Eighth Joint National Committee (JNC 8) guidelines, minoxidil is not recommended for the initial treatment of hypertension (James, 2013).

Contraindications

Hypersensitivity to minoxidil or any component of the formulation; pheochromocytoma

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

Dosing: Adult

Hypertension: Oral: Initial: 5 mg once daily, increase dose gradually in single or divided doses every 3 days or more (or every 6 hours with careful monitoring if rapid management required) (maximum: 100 mg daily); usual dosage range: 10 to 40 mg (manufacturer's labeling); others have recommended 5 to 10 mg daily (ASH/ISH [Weber, 2014])

Note: Dosage adjustment is needed when added to concomitant therapy. If supine diastolic pressure reduced <30 mm Hg, administer dose once daily; if supine diastolic pressure reduced >30 mm Hg, administer dose in 2 divided equal parts

Dosage adjustment with concomitant therapy: Canadian labeling: Consider initiating minoxidil at a reduced dose in patients receiving strong UGT inhibitors (eg, valproic acid, atazanavir, probenecid)

Dosing: Geriatric

Hypertension: Initial: 2.5 mg once daily; increase gradually (ASH/ISH [Weber, 2014])

Dosing: Pediatric

Hypertension:

Children <12 years: Oral: Initial: 0.2 mg/kg once daily; maximum daily initial dose: 5 mg daily; titrate gradually to effect every 3 days; usual dosage: 0.25 to 1 mg/kg/day in 1 to 3 divided doses (NHLBI, 2005); maximum daily dose: 50 mg daily

Children ≥12 years and Adolescents: Refer to adult dosing

Dosing: Renal Impairment

There are no specific dosage recommendations provided in the manufacturer's labeling; however, the manufacturer suggests that patients with renal failure and/or receiving dialysis may require a dosage reduction.

Dosing: Hepatic Impairment

US labeling: There are no dosage adjustments provided in the manufacturer's labeling.

Canadian labeling:

Mild or moderate impairment: There are no specific dosage adjustments provided in the manufacturer's labeling; however, a reduced dosage should be considered.

Severe impairment: Use is contraindicated.

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

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

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

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: Blood Pressure Lowering Agents may enhance the hypotensive effect of Levodopa. 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

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 reported.

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: Breast tenderness (rare; <1%), 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% (Limited to important or life-threatening): 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.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

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

Blood pressure, standing and sitting/supine; signs/symptoms of pericardial effusion; 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.

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

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience hair growth, vomiting, or nausea. Have patient report immediately to prescriber shortness of breath, angina, arm pain, shoulder pain, tachycardia, dizziness, passing out, arrhythmia, heartburn, hearing impairment, vision changes, weight gain, or swelling of arms or legs (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

Hide