Furosemide

General

Type: Diuretic
Dosage Forms:20, 40, 80
Common Trade Names: Lasix
Approximately 50% bioavailability, so converting from oral to IV dose doubles oral dose^[1]
Furosemide absorption may be reduced in decompensated CHF^[2]

40 mg furosemide = 20 mg torsemide = 1 mg bumetanide = 50 mg ethacrynic acid

Fluid overload: Typically 40 mg IV or normal PO dosage IV
hypertension: 10-40 mg PO QDAY-BID, max 600 mg/day
Hypercalcemia: 120 mg/day PO divided QDAY - TID
Continuous infusion may increase diuresis effect and minimize post-diuretic sodium retention and "diuretic braking"^[3]
- Start 0.1 mg/kg/hr, increase hourly to max of 0.75 mg/kg/hr^[4]
- Target > 1 mL/kg/hr
- Monitor for ototoxicity

Pregnancy Rating:C
Lactation: safety unknown
Renal Dosing
- Adult: no adjustment, contraindicated in anuria
- Pediatric: no adjustment, contraindicated in anuria
Hepatic Dosing
- Adult: not defined
- Pediatric: not defined

Half-life: 30-60 min
Metabolism: liver minimally
Excretion: urine
Mechanism of Action: inhibits loop of henle and proximal and distal convoluted tubule sodium and chloride resorption

↑ Asare K. Management of Loop Diuretic Resistance in the Intensive Care Unit. Am J Health Syst Pharm. 2009;66(18):1635-1640.
↑ Vasko MR, Brown-Cartwright D, Knochel JP et al. Furosemide absorption is altered in decompensated congestive heart failure. Ann Intern Med. 1985; 102: 314–8.
↑ Pivac N, Rumboldt Z, Sardelic S et al. Diuretic effects of furosemide infusion versus bolus injection in congestive heart failure. Int J Clin Pharmacol Res. 1998; 18:121–8.
↑ Schuller D, Lynch JP, Fine D. Protocol-guided diuretic management: comparison of furosemide by continuous infusion and intermittent bolus. Crit Care Med. 1997; 25:1969–75.