Furosemide

If given in excessive amounts, furosemide, similar to other loop diuretics, can lead to profound diuresis, resulting in fluid and electrolyte depletion. Close medical supervision and dose evaluation are required. Watch for and correct electrolyte disturbances; adjust dose to avoid dehydration. When electrolyte depletion is present, therapy should not be initiated unless serum electrolytes, especially potassium, are normalized. Risk of hypokalemia may be increased by: rapid diuresis, poor oral potassium intake, cirrhosis, and combined use with large amounts of licorice, corticosteroids, or laxatives (chronic use). In contrast to thiazide diuretics, a loop diuretic can also lower serum calcium concentrations. Electrolyte disturbances can predispose a patient to serious cardiac arrhythmias.

Asymptomatic hyperuricemia has been reported with use; rarely, may precipitate gout.

Monitor fluid status and renal function in an attempt to prevent oliguria, azotemia, and reversible increases in BUN and creatinine; close medical supervision of aggressive diuresis required. May increase risk of radiocontrast-induced nephropathy in high-risk patients.

Rapid IV administration, severe renal impairment, excessive doses, hypoproteinemia, and concurrent use of other ototoxins is associated with ototoxicity.

Photosensitization may occur.

The approved product labeling for many medications containing a sulfonamide chemical group includes a broad contraindication in patients with a prior allergic reaction to sulfonamides. There is a potential for cross-reactivity between members of a specific class (eg, two antibiotic sulfonamides). However, concerns for cross-reactivity have previously extended to all compounds containing the sulfonamide structure (SO2NH2). An expanded understanding of allergic mechanisms indicates cross-reactivity between antibiotic sulfonamides and nonantibiotic sulfonamides may not occur or at the very least this potential is extremely low (Brackett 2004; Johnson 2005; Slatore 2004; Tornero 2004). In particular, mechanisms of cross-reaction due to antibody production (anaphylaxis) are unlikely to occur with nonantibiotic sulfonamides. T-cell-mediated (type IV) reactions (eg, maculopapular rash) are less well understood and it is not possible to completely exclude this potential based on current insights. In cases where prior reactions were severe (Stevens-Johnson syndrome/TEN), some clinicians choose to avoid exposure to these classes.

Doses >80 mg may result in transient increase in free thyroid hormones, followed by an overall decrease in total thyroid hormone levels. Disease-related concerns:

Avoid use of diuretics for treatment of elevated blood pressure in patients with primary adrenal insufficiency (Addison disease). Adjustment of glucocorticoid/mineralocorticoid therapy and/or use of other antihypertensive agents is preferred to treat hypertension (Bornstein 2016; Inder 2015).

In cirrhosis, avoid electrolyte and acid/base imbalances that might lead to hepatic encephalopathy; correct electrolyte and acid/base imbalances prior to initiation when hepatic coma is present. Supplemental potassium or an aldosterone antagonist, when appropriate, may reduce risk of hypokalemia and metabolic alkalosis. Close monitoring warranted, especially with initiation of therapy.

Use with caution in patients with prediabetes or diabetes mellitus; may see a change in glucose control.

May cause urinary retention due to increased urine production, especially upon initiation of therapy.

May cause SLE exacerbation or activation. Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

May lead to nephrocalcinosis or nephrolithiasis in premature infants or in children • Surgical patients: If given the morning of surgery, furosemide may render the patient volume depleted and blood pressure may be labile during general anesthesia. Dosage form specific issues:

Some dosage forms may contain propylene glycol; large amounts are potentially toxic and have been associated hyperosmolality, lactic acidosis, seizures, and respiratory depression; use caution (AAP 1997; Zar 2007). Other warnings and precautions:

For some patients, despite higher doses of loop diuretic treatment, an adequate diuretic response cannot be attained. Diuretic resistance can usually be overcome by intravenous administration, the use of two diuretics together (eg, furosemide and chlorothiazide), or the use of a diuretic with a positive inotropic agent. When such combinations are used, serum electrolytes need to be monitored even more closely (ACC/AHA [Yancy 2013]; Cody 1994; HFSA 2010).