Effect of albumin-bound furosemide on the endocochlear potential of the chinchilla. Alleviation of furosemide-induced ototoxicity.

The effects of albumin-unbound furosemide and albumin-bound furosemide on the cochlear function were compared by the continuous observation of the endocochlear potential (EP) in the chinchilla using the microelectrode method. The EP depression following the intravenous injection of 50 mg/kg of furosemide was 108.5 +/- 2.7 mV, while the addition of 1.0 and 1.3 g/kg of albumin induced the EP depression to be 35.0 +/- 4.8 and 8.1 +/- 1.9 mV, respectively, and both prolonged the time to attain the minimum EP. However, there was no difference in the recovery time of the EP between the two groups. The results indicate that access to the site of furosemide action in the cochlea is dependent on the unbound fraction of furosemide and that the albumin-bound furosemide alleviates the EP depression induced by furosemide alone with the augmentation of diuresis.