| Furosemide (Lasix) is a loop diuretic that is commonly used to treat such pathologies as congestive heart failure in infants and adults, hypertension, the edema associated with acute and chronic renal failure, and bronchopulmonary dysplasia in the newborn. The use of this drug, however, has been associated with clinical reports of transient or permanent hearing loss, tinnitus, and dizziness in adult patients. Although furosemide is commonly used with newborns in the neonatal intensive care unit, it is difficult to assess the ototoxic effect of the drug in this population due to the many other factors and pathologic conditions which may put them at risk for hearing impairment. With the recent NIH consensus panel recommendation for universal hearing screening of newborns using evoked otoacoustic emissions (EOAE) and auditory evoked potentials (AEP), any effect this commonly used drug may have on the outcome of these measures of auditory function must be investigated. Also, the importance of determining the sensitivity of these instruments to cochlear changes caused by the administration of ototoxic medications is clear. In animals, furosemide causes reversible changes in compound action potential amplitude and threshold, as well as distortion product otoacoustic emission amplitudes, when administered in high doses. No reports, however, discuss the effects of clinical doses of furosemide on these auditory evoked responses. In addition, there are no reports involving non-human primates, which are phylogenetically similar to the human species. This study examined the changes seen in distortion product otoacoustic emissions and auditory brainstem response following the administration of clinical doses of furosemide (2mg/kg to 12 mg/kg) in a non-human primate (Macaca mulatta) using equipment designed for clinical measurement. No change in DPOAE amplitude or ABR wave V threshold and latency could be confidently attributed to any of the clinical doses administered in this study. DPOAE amplitudes were, however, influenced by middle ear pressure fluctuations over time. The results of this study clearly indicate the need to document middle ear status prior to DPOAE measurement. |
