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Pronunciation:

(mi NOKS i dil)

U.S. Brand Names:

Loniten®; Rogaine® Extra Strength for Men [OTC]; Rogaine® for Men [OTC]; Rogaine® for Women [OTC]

Generic Available:

Yes

Canadian Brand Names:

Apo-Gain®; Minox; Rogaine®

Use:

Management of severe hypertension (usually in combination with a diuretic and beta-blocker); treatment (topical formulation) of alopecia androgenetica in males and females

Pregnancy Risk Factor:

Contraindications:

Hypersensitivity to minoxidil or any component of the formulation; pheochromocytoma; acute MI; dissecting aortic aneurysm

Warnings/Precautions:

Maximum therapeutic doses of a diuretic and two antihypertensives should be used before this drug is ever added. It can cause pericardial effusion, tamponade, or exacerbate angina pectoris. Monitor patients who are receiving guanethidine concurrently (orthostasis can be problematic). May need to add a diuretic to minimize fluid gain and a beta-blocker (if no contraindications) to treat tachycardia. Rapid control of blood pressure can lead to syncope, CVA, MI, ischemia. Hypersensitivity reactions occur rarely. Avoid use for a month after acute MI. Inform patients of hair growth patterns before initiating therapy. May take 1-6 months for hypertrichosis to reverse itself after discontinuation of the drug. Use with caution in patients with pulmonary hypertension, significant renal failure, CHF, or ischemic disease. Renal failure and dialysis patients may require a smaller dose.

Adverse Reactions:

Oral: Incidence of reactions not always reported.

Cardiovascular: Peripheral edema (7%), sodium and water retention, CHF, tachycardia, angina pectoris, pericardial effusion with or without tamponade, pericarditis, ECG changes (T-wave changes, 60%), rebound hypertension (in children after a gradual withdrawal)

Central nervous system: Headache (rare), fatigue

Dermatologic: Hypertrichosis (common, 80%), transient pruritus, changes in pigmentation (rare), serosanguineous bullae (rare), rash (rare), Stevens-Johnson syndrome

Endocrine & metabolic: Breast tenderness (rare, <1%), gynecomastia (rare), polymenorrhea (rare)

Gastrointestinal: Weight gain, nausea (rare), vomiting

Hematologic: Intermittent claudication (rare), thrombocytopenia (rare), decreased hematocrit (hemodilution), decreased hemoglobin (hemodilution), decreased erythrocyte count (hemodilution), leukopenia (rare)

Hepatic: Increased alkaline phosphatase

Renal: Transient increase in serum BUN and creatinine

Respiratory: Pulmonary edema

Topical: Incidence of adverse events is not always reported.

Cardiovascular: Increased left ventricular end-diastolic volume, increased cardiac output, increased left ventricular mass, dizziness, tachycardia, edema, transient chest pain, palpitation, increase or decrease in blood pressure, increase or decrease in pulse rate (1.5%, placebo 1.6%)

Central nervous system: Headache, dizziness, taste alterations, faintness, lightheadedness (3.4%, placebo 3.5%), vertigo (1.2%, placebo 1.2%), anxiety (rare), mental depression (rare), fatigue (rare 0.4%, placebo 1%)

Dermatologic: Local irritation, dryness, erythema, allergic contact dermatitis (7.4%, placebo 5.4%), pruritus, scaling/flaking, eczema, seborrhea, papular rash, folliculitis, local erythema, flushing, exacerbation of hair loss, alopecia, hypertrichosis, increased hair growth outside the area of application (face, beard, eyebrows, ear, arm)

Endocrine & metabolic: Menstrual changes, breast symptoms (0.5%, placebo 0.5%)

Gastrointestinal: Diarrhea, nausea, vomiting (4.3%, placebo 6.6%), weight gain (1.2%, placebo 1.3%)

Genitourinary: Urinary tract infection (rare), renal calculi (rare), urethritis (rare), prostatitis (rare), epididymitis (rare), impotence (rare)

Hematologic: Lymphadenopathy, thrombocytopenia, anemia (0.3%, placebo 0.6%)

Neuromuscular & skeletal: Fractures, back pain, retrosternal chest pain of muscular origin, tendonitis (2.6%, placebo 2.2%), weakness

Ocular: Conjunctivitis, visual disturbances, decreased visual acuity

Respiratory: Bronchitis, upper respiratory infection, sinusitis (7.2%, placebo 8.6%)

Overdosage/Toxicology:

Symptoms of overdose include hypotension, tachycardia, headache, nausea, dizziness, weakness syncope, warm flushed skin and palpitations; lethargy and ataxia may occur in children

Hypotension usually responds to I.V. fluids, Trendelenburg positioning or vasoconstrictor; treatment is primarily supportive and symptomatic

Drug Interactions:

Antihypertensives: Effects may be additive.

Guanethidine can cause severe orthostasis; avoid concurrent use - discontinue 1-3 weeks prior to initiating minoxidil.

Ethanol/Nutrition/Herb Interactions:

Herb/Nutraceutical: Avoid natural licorice (causes sodium and water retention and increases potassium loss).

Stability:

Store at controlled room temperature of 20°C to 25°C (68°F to 77°F).

Mechanism of Action:

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

Pharmacodynamics/Kinetics:

Onset of action: Hypotensive: Oral: ~30 minutes

Peak effect: 2-8 hours

Duration: 2-5 days

Protein binding: None

Metabolism: 88%, primarily via glucuronidation

Bioavailability: Oral: 90%

Half-life elimination: Adults: 3.5-4.2 hours

Excretion: Urine (12% as unchanged drug)

Dosage:

Children <12 years: Hypertension: Oral: Initial: 0.1-0.2 mg/kg once daily; maximum: 5 mg/day; increase gradually every 3 days; usual dosage: 0.25-1 mg/kg/day in 1-2 divided doses; maximum: 50 mg/day

Children >12 years and Adults: Hypertension: Oral: Initial: 5 mg once daily, increase gradually every 3 days (maximum: 100 mg/day); usual dose range (JNC 7): 2.5-80 mg/day in 1-2 divided doses

Adults: Alopecia: Topical: Apply twice daily; 4 months of therapy may be necessary for hair growth.

Elderly: Initial: 2.5 mg once daily; increase gradually.

Note: Dosage adjustment is needed when added to concomitant therapy.

Dialysis: Supplemental dose is not necessary via hemo- or peritoneal dialysis.

Monitoring Parameters:

Blood pressure, standing and sitting/supine; fluid and electrolyte balance and body weight should be monitored

Patient Education:

Topical product is for external use only. When using the topical product, do not use other topical medications on the scalp. Topical product must be used every day. Hair growth usually takes 4 months. Notify physician if any of the following occur: Heart rate 20 beats per minute over normal; rapid weight gain >5 lb (2 kg); unusual swelling of extremities, face, or abdomen; breathing difficulty, especially when lying down; rise slowly from prolonged lying or sitting; new or aggravated angina symptoms (chest, arm, or shoulder pain); severe indigestion; dizziness, lightheadedness, or fainting; nausea or vomiting may occur. Do not make up for missed doses. Pregnancy precaution: Inform prescriber if you are or intend to become pregnant.

Nursing Implications:

May cause hirsutism or hypertrichosis; observe for fluid retention and orthostatic hypotension

Anesthesia and Critical Care Concerns/Other Considerations:

Minoxidil when used in patients with hypertension will not cause regression of left ventricular hypertrophy.

Cardiovascular Considerations:

Widespread use of topical minoxidil for hair growth has been made possible by the availability of minoxidil solutions over-the-counter. An increased concentration strength (5% solution) for use by men only may result in some systemic absorption of minoxidil. Note that when minoxidil is used orally, it may cause pericardial effusion. Minoxidil when used in patients with hypertension will not cause regression of left ventricular hypertrophy.

Dental Health: Effects on Dental Treatment:

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions:

No information available to require special precautions

Mental Health: Effects on Mental Status:

May cause dizziness

Mental Health: Effects on Psychiatric Treatment:

May rarely cause leukopenia; use caution with clozapine and carbamazepine

Dosage Forms:

Solution, topical: 2% [20 mg/metered dose] (60 mL); 5% [50 mg/metered dose] (60 mL)

Rogaine® for Men, Rogaine® for Women: 2% [20 mg/metered dose] (60 mL)

Rogaine® Extra Strength for Men: 5% [50 mg/metered dose] (60 mL)

Tablet (Loniten®): 2.5 mg, 10 mg

International Brand Names:

Alopexy® (CH, FR, LU, RO); Alostil® (FR); Aloxidil® (IT); Apo-Gain® (CA, NZ); Biocrinal® (PT); Crinalsofex® (PT); Dinaxil Capilar® (ES); Hairgaine® (IL); Hair Grow® (HK, JO, KW, LB, MT, MY, RO); Headway® (NZ); Lacovin® (ES); Locemix® (AR); Locion EPC® (DO); Loninoten® (BE); Loniten® (AT, AU, CH, ES, GB, IE, IT, PL, PT, SI, TH); Lonnoten® (BE, LU, NL); Lonolox® (AR, DE); Lonoten® (FR); Loxon® (PL); Macbirs® (AR); Mantai® (PT); Minocalve® (PT); Minovital® (IT); Minox (CA); Minoxidil Cooper® (FR); Minoxidil® (CY, IL); Minoxidil Galderma® (ES); Minoxidil Gerbiol® (FR); Minoxidil MK® (CO); Minoxidil Thera France® (FR); Minoxi® (IL); Minoxile® (AR); Minoximen® (IT); Minoxitrim® (RO, SG); Modil® (TH); Neocapil® (CH, CZ); Neoxidil® (BE, BR, IL, LU, SG); Normoxidil® (IT); Noxidil® (TH); Nuhair® (TH); Pilfud® (HR); Piloxidil® (PL); Recrea® (SE); Regaine® (AR, AT, AU, BE, BG, BR, CH, CL, CZ, DE, DK, ES, FI, FR, GB, HK, HR, HU, ID, IE, IL, IT, LU, MX, NL, NO, NZ, PL, PT, RO, RU, SE, SG, SI, ZA); Regalok® (PL); Regro® (SG); Regrou® (ID); Regrowth® (TH); Revexan® (SE); Riteban® (ES); Rogaine® (AT, CA, NZ, SE); Toneon® (AR); Tricolocion® (AR); Tricoplus® (AR); Tricovivax® (PT); Tricoxane® (AR, CL); Tricoxidil® (IT); Ylox® (AR); Zeldilon® (PT)

References

Allon M, Hall D, and Macon EJ, "Prolonged Hypotension After Initial Minoxidil Dose,"Arch Intern Med, 1986, 146(10):2075-6.

Chobanian AV, Bakris GL, Black HR, et al, "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report,"JAMA, 2003, 289 (19):2560-71.

Franciosa JA, Jordan RA, Wilen MM, et al, "Minoxidil in Patients With Chronic Left Heart Failure: Contrasting Hemodynamic and Clinical Effects in a Controlled Trial,"Circulation, 1984, 70(1):63-8.

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