Medical term:

Loniten

minoxidil

Apo-Gain (CA), Gen-Minoxidil (CA), Loniten (UK) (CA), Minox (CA), Regaine (UK), Rogaine, Rogaine Extra Strength

Pharmacologic class: Peripheral vasodilator (direct-acting)

Therapeutic class: Antihypertensive, hair growth stimulant

Pregnancy risk category C

FDA Box Warning

• Drug may cause serious adverse effects (such as pericardial effusion occasionally progressing to tamponade) and may exacerbate angina pectoris. Reserve it for hypertensive patients who respond inadequately to maximum therapeutic doses of diuretic and two other antihypertensives.

• Give under close supervision, usually concurrently with therapeutic doses of beta blocker to prevent tachycardia and increased myocardial workload. Usually, drug also must be given with diuretic to prevent serious fluid accumulation. Patients with malignant hypertension and those already receiving guanethidine should be hospitalized when therapy begins so they can be monitored to avoid too rapid, or large orthostatic, blood pressure decreases.

Action

Reduces blood pressure by relaxing vascular smooth muscle, causing vasodilation. Action in hair growth stimulation unclear; vasodilatory action may enhance microcirculation around hair follicles.

Availability

Tablets: 2.5 mg, 10 mg

Topical solution: 2%, 5%

Indications and dosages

➣ Severe symptomatic hypertension; hypertension associated with end-organ damage

Adults and children ages 12 and older: 5 mg/day as a single dose, increased carefully q 3 days. Usual range is 10 to 40 mg/day in single or divided doses. For rapid blood pressure control with careful monitoring, dosage may be adjusted q 6 hr. Maximum dosage is 100 mg/day.

Children younger than age 12: 0.2 mg/kg/day P.O. as a single dose. May increase in increments of 50% to 100% until blood pressure control is optimal. Usual range is 0.25 to 1 mg/kg/day; maximum recommended dosage is 50 mg/day.

➣ Male-pattern baldness; diffuse hair loss or thinning in women; adjunct to hair transplantation

Adults: Apply 1 ml of 2% or 5% topical solution to affected area b.i.d. for 4 months or longer.

➣ Alopecia areata

Adults: Apply 1 ml of 2% or 5% topical solution to scalp b.i.d.

Contraindications

• Hypersensitivity to drug or its components

• Dissecting aortic aneurysm

• Pheochromocytoma

Precautions

Use cautiously in:

• recent MI, malignant hypertension, heart failure, angina pectoris, severe renal impairment

• concurrent guanethidine therapy

• pregnant or breastfeeding patients.

Administration

• Give oral form with meals to decrease GI upset.

☞ If patient is also receiving guanethidine, discontinue that drug 1 to 3 days before starting minoxidil, to avoid severe orthostatic hypotension.

• Know that oral form is usually given with a beta-adrenergic blocker or diuretic to control hypertension.

Adverse reactions

CV: ECG changes (such as T-wave changes), tachycardia, angina, pericardial effusion, cardiac tamponade, heart failure

GI: nausea, vomiting

Respiratory: pulmonary edema

Skin: hypertrichosis

Other: weight gain, edema

Interactions

Drug-drug. Antihypertensives, nitrates: additive hypotension

Guanethidine: severe orthostatic hypotension

Nonsteroidal anti-inflammatory drugs: decreased minoxidil efficacy

Drug-diagnostic tests. Alkaline phosphatase, blood urea nitrogen, creatinine, plasma renin activity, sodium: increased levels

Hematocrit, hemoglobin, red blood cells: decreased levels

Patient monitoring

• Monitor vital signs and ECG.

• Assess daily weight and fluid intake and output.

☞ Monitor cardiovascular status carefully. Stay alert for signs and symptoms of heart failure.

• Watch for hypertrichosis.

• Know that hematologic and renal values usually return to pretreatment levels with continued therapy.

Patient teaching

• Instruct patient to take oral form with meals to decrease GI upset.

• Advise patient to weigh himself daily and report sudden gains.

• Tell patient taking oral form that drug may darken, lengthen, and thicken body hair. Tell him to shave or use depilatory to reduce unwanted hair growth. Reassure him that unwanted growth will disappear 1 to 6 months after he stops taking drug.

☞ Instruct patient to immediately report difficulty breathing (especially when lying down) or pain in chest, arm, or shoulder.

• Teach patient how to use topical form. Urge him to read package insert carefully.

• Caution patient not to use topical form on other body parts and not to let it contact mucous membranes.

• Tell patient using topical form that new scalp hair will be soft and barely visible. Caution him to use only 1 ml twice daily, regardless of amount of balding. Remind him not to stop using drug suddenly, because new hair growth will be lost.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

minoxidil (systemic)

(mi-nox-i-dill) ,

Loniten

(trade name)

Classification

Therapeutic: antihypertensives
Pharmacologic: vasodilators

Pregnancy Category: C

Indications

Severe symptomatic hypertension or hypertension associated with end-organ damage that has failed to respond to combinations of more conventional therapy.

Action

Directly relaxes vascular smooth muscle, probably by inhibiting the enzyme phosphodiesterase. Results in vasodilation, which is more pronounced in arterioles than veins.

Therapeutic effects

Lowering of BP.

Pharmacokinetics

Absorption: Well absorbed following oral administration.

Distribution: Widely distributed; enters breast milk.

Metabolism and Excretion: 90% metabolized by the liver.

Half-life: 4.2 hr.

Time/action profile (antihypertensive effect)

ROUTE	ONSET	PEAK	DURATION
PO	30 min	2–3 hr	2–5 days

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Pheochromocytoma.

Use Cautiously in: Recent MI; Severe renal impairment (can be used in moderate renal impairment); Geriatric: May be more sensitive to effects; consider age-related ↓ in body mass and hepatic/renal/cardiovascular function; Obstetric / Lactation: Safety not established.

Adverse Reactions/Side Effects

Central nervous system

headache

Respiratory

pulmonary edema (life-threatening)

Cardiovascular

HF (life-threatening)
ECG changes (alteration in T waves) (most frequent)
tachycardia (most frequent)
angina
pericardial effusion

Gastrointestinal

nausea

Dermatologic

hypertrichosis (most frequent)
pigment changes
rash

Endocrinologic

gynecomastia
menstrual irregularities

Fluid and Electrolyte

sodium and water retention (most frequent)

Miscellaneous

intermittent claudication

Interactions

Drug-Drug interaction

Additive hypotensive effects with other antihypertensives, acute ingestion of alcohol, or nitrates.NSAIDs may ↓ the antihypertensive effectiveness of minoxidil.

Route/Dosage

Oral (Adults and Children >12 yr) Hypertension—5 mg once daily or in 2 divided doses; may double at 3-day intervals; usual range 10–40 mg/day (for rapid control with careful monitoring, doses may be adjusted q 6 hr; up to 100 mg/day has been used).

Oral (Children <12 yr) Hypertension—0.2 mg/kg/day (5 mg maximum) as a single dose or 2 divided doses; may be gradually ↑ at 3-day intervals in increments of 50–100% until response is obtained; usual range 0.25–1 mg/kg/day (for rapid control, doses may be adjusted q 6 hr; not to exceed 50 mg/day).

Availability (generic available)

Tablets: 2.5 mg, 10 mg

Nursing implications

Nursing assessment

Hypertension: Monitor BP and pulse frequently during initial dose adjustment and periodically during therapy. Report significant changes.
- Monitor frequency of prescription refills to determine adherence.
- Monitor intake and output ratios and daily weight and assess for edema daily, especially at beginning of therapy. Report weight gain or edema; sodium and water retention may be treated with diuretics.
Lab Test Considerations: Monitor renal and hepatic function, CBC, and electrolytes prior to and periodically during therapy.
- May cause ↑ BUN, serum creatinine, alkaline phosphatase, plasma renin activity (PRA), and sodium levels. May also cause ↓ RBC, hemoglobin, and hematocrit counts. Hematologic and renal values usually return to pretreatment levels with continued therapy.

Potential Nursing Diagnoses

Ineffective tissue perfusion (Indications)

Implementation

Do not confuse Loniten (minoxidil) with Lipitor (atorvastatin).
Hypertension: Medication may need to be discontinued gradually to prevent rebound hypertension.
- Minoxidil is given concurrently with a diuretic unless patient is on hemodialysis.
- Dose adjustments should not be made more frequently than every 3 days to allow for maximum effectiveness, unless rapid control is necessary.
Oral: May be administered without regard to meals or food.

Patient/Family Teaching

Emphasize the importance of continuing to take this medication, even if feeling well. Instruct patient to take medication at the same time each day. Take missed doses as soon as remembered if within a few hours; otherwise, omit dose and return to regular dose schedule. Do not double doses. Advise patient not to discontinue minoxidil or other antihypertensive medications without consulting health care professional. Minoxidil helps control but does not cure hypertension.
- Encourage patient to comply with additional interventions for hypertension (weight reduction, low-sodium diet, smoking cessation, moderation of alcohol consumption, regular exercise, and stress management).
- Instruct patient and family on proper technique for weekly pulse and BP monitoring. Advise them to report significant changes to health care professional, who should also be notified if resting pulse increases more than 20 bpm above baseline.
- Advise patient to check weight daily and to notify health care professional of rapid weight gain of >5 lb or if signs of fluid retention occur.
- Caution patient to change positions slowly to minimize orthostatic hypotension.
- Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications, especially cough, cold, or allergy remedies or herbal products.
- Inform patient that depilatory creams may minimize increased hair growth. This is temporary and is reversible within 1–6 mo following discontinuation of minoxidil.
- Advise patient to notify health care professional if unusual swelling of face, extremities, or abdomen; difficulty breathing, especially when lying down; new or aggravated angina; severe indigestion; dizziness or fainting occurs.

Evaluation/Desired Outcomes

Decrease in BP without appearance of serious side effects.

Loniten

A brand name for MINOXIDIL.

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