Minoxidil

CLINICAL USE

Severe hypertension (in addition to a diuretic and a beta-blocker)Male pattern baldness

DOSE IN NORMAL RENAL FUNCTION

Initially 5 mg (elderly 2.5 mg) daily in 1–2 doses increased by 5–10 mg every 3 or more days; maximum 50 mg dailyMale pattern baldness: 1 mL twice daily

PHARMACOKINETICS

Molecular weight :209.2

%Protein binding :0

%Excreted unchanged in urine : 15–20

Volume of distribution (L/kg) : 2–3

half-life – normal/ESRD (hrs) :4.2/8.9

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Start with small doses and titrate according to response.

10 to 20 : Start with small doses and titrate according to response.

<10 : Start with small doses and titrate according to response.

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Dialysed. Dose as in GFR <10 mL/min

HD :Dialysed. Dose as in GFR <10 mL/min

HDF/high flux :Dialysed. Dose as in GFR <10 mL/min

CAV/VVHD :Dialysed. Dose as in GFR=10-20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Anaesthetics: enhanced hypotensive effect

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

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OTHER INFORMATION

A study of the pharmacokinetics of minoxidil in patients with varying degrees of renal impairment found that the non-renal clearance was also impaired as renal function worsened. Substantial accumulation of minoxidil might occur in these patients during multiple-dose therapy. Recommended that minoxidil therapy be initiated with smaller doses or a longer dose interval in patients with significant renal impairmentMinoxidil is a peripheral vasodilator and should be given in conjunction with a diuretic to control salt and water retention, and a beta-blocker to control reflex tachycardia. Patients on dialysis do not need to be given minoxidil in conjunction with a diureticFollowing topical application, between 0.3% and 4.5% of the total applied dose of minoxidil is absorbed from intact scalp.

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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