Dose and Administration

1. Intravenous and oral dosing ^1,2,4

   	Route	Dose	Dose Interval (hr)
   <32 weeks	IV	1mg/kg/dose	24
   	Oral	1-2mg/kg/dose	24
   ≥32 weeks	IV	1mg/kg/dose	12-24
   	Oral	1-2mg/kg/dose	12-24

2. Infusion: ³  Maximum dose of 1mg/kg/hour in those infants in whom an aggressive yet controlled diuresis is required.
   Commence at 0.3mg/kg/hour and titrate according to urinary output.
   Usual dilution 50mg/kg furosemide to make 50ml with D5W or D10W.  1ml/hour = 1mg/kg/hour.

Indications

1. Fluid overload (iatrogenic, congestive heart failure, renal failure, other).
2. Chronic lung disease.

Contraindications and Precautions

1. Known hypersensitivity to furosemide.
2. Caution in preterm infants, especially extreme immaturity.
3. Caution in infants with renal impairment.
4. Caution in infants with jaundice.
5. Caution in infants with hyponatraemia and/or hypokalaemia.

Clinical Pharmacology

Furosemide is a potent loop diuretic with rapid action. The drug inhibits chloride reabsorption in the ascending limb of the Loop of Henle and inhibits tubular sodium transport, causing major loss of sodium and chloride. Increased urinary losses of potassium, calcium and phosphate (large doses only) also occur. Urine pH increases. Furosemide also increases renal blood flow.

Furosemide is rapidly absorbed from the gastrointestinal tract (bioavailability 60-70%). The half life in adults is 2 hours, but this is approximately 8 times greater in neonates.  It is approximately 99% bound to plasma proteins, and excreted mainly unchanged by the kidneys.

Possible Adverse Effects ^6,7

1. Dehydration, hypotension.
2. Gastrointestinal disturbance (oral administration).
3. Hyponatraemia, hypokalaemia, hypochloraemic metabolic alkalosis.
4. Hypercalciuria, hypocalcaemia, nephrocalcinosis.
5. Rash.
6. Ototoxicity (especially in those also receiving nephrotoxic drugs).
7. Nephrotoxicity.

Drug Interactions

Special Considerations

1. Electrolyte aberrations occur frequently and should be anticipated and monitored.
   • Sodium, potassium and chloride supplements are usually required with long-term use of furosemide.
   • Need to monitor calcium levels with long term use.
2. Dosing regime determined by clinical response and infant's maturity.
3. Placement of an indwelling urinary catheter should be mandatory for infants receiving continuous infusions of furosemide.