Furosemide

CLINICAL USE

Loop diuretic

DOSE IN NORMAL RENAL FUNCTION

Oral: 20 mg – 1 g dailyIV: 20 mg – 1.5 g dailyDoses titrated to response

PHARMACOKINETICS

Molecular weight :330.7

%Protein binding :91–99

%Excreted unchanged in urine : 80–90

Volume of distribution (L/kg) :0.07–0.2

half-life – normal/ESRD (hrs) :0.5–2/9.7

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; increased doses may be required

<10 : Dose as in normal renal function; increased doses may be required

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Not dialysed. Dose as in GFR <10 mL/min

HD :Not dialysed. Dose as in GFR <10 mL/min

HDF/high flux :Not dialysed. Dose as in GFR <10 mL/min

CAV/VVHD :Not dialysed. Dose as in GFR=10–20 mL/min

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Analgesics: increased risk of nephrotoxicity with NSAIDs; antagonism of diuretic effect with NSAIDs

Anti-arrhythmics: risk of cardiac toxicity with anti-arrhythmics if hypokalaemia occurs; effects of lidocaine and mexiletine antagonised

Antibacterials: increased risk of ototoxicity with aminoglycosides, polymyxins and vancomycin; avoid concomitant use with lymecycline

Antidepressants: increased risk of hypokalaemia with reboxetine; enhanced hypotensive effect with MAOIs; increased risk of postural hypotension with tricyclics

Anti-epileptics: increased risk of hyponatraemia with carbamazepine

Antifungals: increased risk of hypokalaemia with amphotericinAntihypertensives: enhanced hypotensive effect; increased risk of first dose hypotensive effect with alpha-blockers; increased risk of ventricular arrhythmias with sotalol if hypokalaemia occurs

Antipsychotics: increased risk of ventricular arrhythmias with amisulpiride, sertindole or pimozide (avoid with pimozide) if hypokalaemia occurs; enhanced hypotensive effect with phenothiazines

Atomoxetine: hypokalaemia increases risk of ventricular arrhythmiasCardiac glycosides: increased toxicity if hypokalaemia occurs

Ciclosporin: variable reports of increased nephrotoxicity, ototoxicity and hepatotoxicity

Lithium: risk of toxicity

ADMINISTRATION

Reconstition

–

Route

IV peripherally or centrally, IM, oral

Rate of Administration

1 hour; not greater than 4 mg/minute

Comments

250 mg to 50 mL sodium chloride 0.9% or undiluted via CRIP Increased danger of ototoxicity and nephrotoxicity if infused at faster rate than approximately 4 mg/minute Protect from light Furosemide (frusemide).FUrosEMidE (FrUsEMidE) 339

OTHER INFORMATION

500 mg orally ≡ 250 mg IVExcreted by tubular secretion, therefore in severe renal impairment (GFR 5-10 mL/min) higher doses may be required due to a reduction in the number of functioning nephronsFurosemide acts within 1 hour of oral administration, (after IV peak effect within 30 minutes) diuresis complete within 6 hours.

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