midodrine hydrochloride

CLINICAL USE

Treatment of orthostatic hypotension, including dialysis related hypotension

DOSE IN NORMAL RENAL FUNCTION

Hypotension: 2.5 mg twice daily up to 10 mg 3 times a day

PHARMACOKINETICS

Molecular weight :290.7

%Protein binding :Negligible

%Excreted unchanged in urine : 2

Volume of distribution (L/kg) :No data

half-life – normal/ESRD (hrs) :25 minutes (3 hours for active metabolite)/increased (9 for active metabolite)

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function. Start with a lower dose and titrate according to response

<10 : Dose as in normal renal function. Start with a lower dose and titrate according to response

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Dialysed. Dose as in GFR

<10 : mL/min

HD :Dialysed. Initial dose, 2.5 mg if <70 kg, 5 mg if >70 kg.

HDF/high flux :Dialysed. Initial dose, 2.5 mg if <70 kg, 5 mg if >70 kg.

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

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsRisk of arrhythmias if given with volatile anaestheticsRisk of arrhythmias and hypertension if given with tricyclic antidepressants and MAOIsRisk of severe hypertension if given with beta-blockersOther drugs which increase blood pressure: enhanced hypertensive effect

ADMINISTRATION

Reconstition

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Route

Oral

Rate of Administration

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Comments

Take last dose at least 4 hours before bed

OTHER INFORMATION

Metabolised to an active metabolite (desglymidodrine)After dialysis only 15% of drug remaining, so effectively removed by dialysisHypertension post dialysis is not a problem because drug is dialysed outPeak levels occur 30 minutes after administration (60 minutes for active metabolite) so give 30 minutes before dialysis – avoid in patients with active coronary ischaemia93% bioavailability For haemodialysis patients, start at a low dose and increase to a maximum of 30 mg; a second dose can be given midway through dialysis (maximum dose 10 mg)

Contraindicated in severe organic heart disease, urinary retention, phaeochromocytoma and thyrotoxicosis

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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