Ototoxicity induced by gentamicin and furosemide.
OBJECTIVE
To present a case of ototoxicity induced by furosemide and once-daily gentamicin therapy.


METHODS
A 60-year-old white woman presented to the hospital with community-acquired pneumonia and urinary tract infection. The antibiotic regimen included gentamicin and, after 5 doses, the patient reported profound bilateral hearing loss. A Pure Tone Audiogram suggested moderate to moderately severe sensorineural hearing loss bilaterally. The only risk factors present included her age, elevated temperature, and the use of furosemide.


CONCLUSIONS
Several risk factors may predispose a patient to developing aminoglycoside ototoxicity: the 1555 chromosomal mutation, preexisting disorders of hearing and balance, hypovolemia, bacteremia, liver and renal dysfunction, and the simultaneous administration of other ototoxic medications. The cumulative dose and duration of aminoglycoside therapy are more important than serum concentrations. Administration of an aminoglycoside followed by furosemide may increase the risk of ototoxicity. The aminoglycoside interacts with the cell membranes in the inner ear, increasing their permeability. This theoretically allows the loop diuretic to penetrate into the cells in higher concentrations, causing more severe damage.


CONCLUSIONS
Auditory toxicity occurred after only 5 days of gentamicin therapy and 1 dose of furosemide. An aminoglycoside followed by furosemide may increase the risk for ototoxicity. Clinicians need to be aware of the synergistic potential of ototoxic medications.
Bates
Duane E
DE
Internal Medicine, Foothills Medical Centre, Calgary, Alberta, Canada. duane.bates@crha-health.ab.ca
Beaumont
Steve J
SJ
Baylis
Barry W
BW
D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D017714:Community-Acquired Infections / Q000188:drug therapy; D004232:Diuretics / Q000009:adverse effects*; D004357:Drug Synergism; D005260:Female; D005665:Furosemide / Q000009:adverse effects*; D005839:Gentamicins / Q000009:adverse effects*; D006319:Hearing Loss, Sensorineural / Q000139:chemically induced*; D006801:Humans; D008875:Middle Aged; D011014:Pneumonia / Q000188:drug therapy; D012307:Risk Factors; D014552:Urinary Tract Infections / Q000188:drug therapy
D000900:Anti-Bacterial Agents; D004232:Diuretics; D005839:Gentamicins; D005665:Furosemide