Furosemide

Furosemide

Indication

• Used in the treatment of fluid overload, pulmonary edema, congestive heart failure and hypertension

Pharmacology

• Inhibits the reabsorption of electrolytes in the ascending loop of Henle
• In the distal renal tubule the reabsorption of Na and Cl is decreased and K excretion is increased
• The excretion of H, Mg, Ca, bicarbonate and ammonium is also increased
• Excessive losses of K, Cl and H may cause metabolic alkalosis
• Causes a significant increase in urinary excretion of Ca (reabsorption in the loop of Henle is linked to Na reabsorption)
• Bioavailability following oral administration in adults is 60 to 70%
• The diuretic effect is usually complete by 6 hours, but longer duration of effects has been reported

Side Effects

• Fluid and electrolyte imbalance: hyponatremia, hypocalcemia, hypokalemia, hypochloremia; dehydration, hypotension from hypovolemia
• Potentially ototoxic (risk increases in severe renal impairment, concomitant use of other potentially ototoxic drugs, eg. gentamicin, and administration at too fast a rate)
• Chronic use can cause nephrocalcinosis and hypochloremic metabolic alkalosis

Nursing/Physician Implications

• Closely monitor serum electrolytes
• Monitor intake and output (accurate) (because the diuretic effect is usually complete by 6 hours, it is reasonable, for single dose therapy, to accurately monitor intake and output for a total of 8 hours following a single IV or oral dose)

Dose

• IV:
  • 1 mg/kg q12-24h by slow IV push over 2 minutes (it may be useful to dilute furosemide with normal saline or D5W for a more accurate delivery of the medication)
  • onset of action is 5 to 15 min
• PO:
  • 1 to 2 mg/kg q12h, increase slowly if needed.
  • onset of action is 30-60 min

Supplied As

• 10 mg/mL, 2 mL ampoule
• 10 mg/mL oral solution