minoxidil (Rx)

Brand and Other Names:Loniten, Minodyl, more...Minoxidil HTN
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 2.5mg
  • 10mg

Severe or Refractory Hypertension (HTN)

Initial: 5mg PO qDay, increase every 3 days PRN

Maintenance: 2.5-80 mg/day qDay or q12hr; not to exceed 100 mg/day

Dosage Forms & Strengths

tablet

  • 2.5mg
  • 10mg

Severe or Refractory Hypertension (HTN)

< 12 years

  • Initial: 0.1-0.2 mg/kg; not to exceed 5 mg/day PO; titrate to response every 3 days  
  • 0.25-1 mg/kg/day PO qDay or q12hr; not to exceed 50 mg/day

> 12 years

  • Initial: 5mg PO qDay, increase every 3 days PRN
  • Maintenance: 2.5-80 mg/day qDay or q12hr; not to exceed 100 mg/day

Hypertension

2.5 mg PO qDay; titrate to response gradually

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Interactions

Interaction Checker

and minoxidil

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    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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            Adverse Effects

            >10%

            Hypertrichosis (80%)

            Abnormal ECG (60%)

            1-10%

            Pericardial effusion (3%)

            Frequency Not Defined

            Angina

            Cardiac tamponade

            Fluid and sodium retention

            Hypotension

            Pericarditis

            Tachyarrhythmia

            Stevens-Johnson syndrome (rare )

            Hirsutism

            Leukopenia (rare)

            Thrombocytopenia (rare)

            Toxic epidermal necrolysis

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            Warnings

            Black Box Warnings

            Can precipitate effusion, occasionally progressing to tamponade

            May exacerbate angina pectoris

            Reserve for patients who do not respond adequately to maximum therapeutic doses of a diuretic and 2 other antihypertensives

            In experimental animals, minoxidil caused several kinds of myocardial lesions as well as other adverse cardiac effects

            Must be administered under close supervision, usually concomitantly with therapeutic doses of a beta-adrenergic blocking agent to prevent tachycardia and increased myocardial workload

            Usually given with a diuretic (typically loop diuretic) to prevent serious fluid accumulation

            Patients with malignant hypertension and those already receiving guanethidine should be hospitalized when minoxidil first administered (monitoring required because risk for rapid/large decrease in BP)

            Contraindications

            Hypersensitivity to minoxidil

            Pheochromocytoma

            Cautions

            Reserve for severe hypertension refractory to other drugs

            In patients with severe blood pressure elevation, too rapid control of blood pressure, especially with intravenous agents, can precipitate syncope, cerebrovascular accidents, myocardial infarction and ischemia of special sense organs with resulting decrease or loss of vision or hearing; patients with compromised circulation or cryoglobulinemia may also suffer ischemic episodes of affected organs

            Patients with malignant hypertension should have initial treatment with minoxidil carried out in a hospital setting, both to assure that blood pressure is falling and to assure that it is not falling more rapidly than intended

            Neonatal hypertrichosis reported following exposure to minoxidil during pregnancy

            Although minoxidil does not itself cause orthostatic hypotension, administration to patients already receiving guanethidine can result in profound orthostatic effects; if at all possible, discontinue guanethidine well before minoxidil is begun; if this is not possible, therapy should be started in hospital and patient should remain institutionalized until severe orthostatic effects are no longer present or patient has learned to avoid activities that provoke them

            Therapy not used in patients who have had a myocardial infarction within preceding month; it is possible that reduction of arterial pressure with drug might further limit blood flow to myocardium, although this might be compensated by decreased oxygen demand because of lower blood pressure

            Patients with renal failure or on dialysis, may require smaller doses and should have close medical supervision to prevent exacerbation of renal failure or precipitation of cardiac failure

            Pericarditis and pericardial effusion

            • There have been reports of pericarditis occurring in association with therapy; the relationship of this association to renal status is uncertain; pericardial effusion, occasionally with tamponade, has been observed in about 3% of treated patients not on dialysis, especially those with inadequate or compromised renal function
            • Although in many cases, pericardial effusion associated with a connective tissue disease, uremic syndrome, congestive heart failure, or marked fluid retention, there have been instances in which these potential causes of effusion were not present; observe patients closely for any suggestion of a pericardial disorder, and perform echocardiographic studies if suspicion arises
            • More vigorous diuretic therapy, dialysis, pericardiocentesis, or surgery may be required; if effusion persists, withdrawal of drug should be considered in light of other means of controlling hypertension and patient’s clinical status

            Concomitant treatment for prevention of tachycardia

            • Therapy increases heart rate; angina may worsen or appear for first time during treatment, probably because of increased oxygen demands associated with increased heart rate and cardiac output
            • Increase in rate and occurrence of angina generally can be prevented by concomitant administration of a beta-adrenergic blocking drug or other sympathetic nervous system suppressant
            • Ability of beta-adrenergic blocking agents to minimize papillary muscle lesions in animals further supports using agent concomitantly; round-the-clock effectiveness of sympathetic suppressant should be ensured

            Water retention

            • Congestive heart failure—concomitant use of adequate diuretic required; drug must usually be administered concomitantly with diuretic adequate to prevent fluid retention and possible congestive heart failure; high ceiling (loop) diuretic is almost always required
            • Monitor body weight if drug is used without a diuretic; retention of several hundred milli-equivalents of salt and corresponding volumes of water can occur within a few days, leading to increased plasma and interstitial fluid volume and local or generalized edema
            • Diuretic treatment alone, or in combination with restricted salt intake, will usually minimize fluid retention, although reversible edema did develop in approximately 10% of nondialysis patients so treated
            • Ascites reported; diuretic effectiveness limited mostly by disease-related impaired renal function; condition of patients with preexisting congestive heart failure occasionally deteriorated in association with fluid retention although because of fall in blood pressure (reduction of afterload), more than twice as many improved than worsened
            • Rarely, refractory fluid retention may require discontinuation of therapy; provided that patient is under close medical supervision, it may be possible to resolve refractory salt retention by discontinuing therapy for 1 or 2 days and then resuming treatment in conjunction with vigorous diuretic therapy
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            Pregnancy & Lactation

            Pregnancy Category: C

            Lactation: controversial; excreted in breast milk, not recommended for long term use if breastfeeding

            Pregnancy Categories

            A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

            B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

            C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

            D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

            X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

            NA: Information not available.

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            Pharmacology

            Mechanism of Action

            Direct vasodilator; dilate arterioles with little effect on vein, decreases systemic resistance, which subsequently decreases blood pressure.

            Pharmacokinetics

            Half-Life: 4 hr

            Excretion: Urine (12% as unchanged drug)

            Duration: 2-5 Days

            Peak Plasma Time: PO (HTN): 1 hr

            Bioavailability: PO (HTN): 90%

            Protein Bound: Negligible

            Metabolism: liver, 88% via glucuronidation

            Metabolite: minoxidil-0-glucuronide (active)

            Onset

            • Initial effect: PO (HTN): 30-60 min
            • Max effect: PO (HTN): 4-8 hr
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            Formulary

            FormularyPatient Discounts

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            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
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            Code Definition
            PA Prior Authorization
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.