The Effect of Erythromycin on Cochlear Potentials.

The mechanism of hearing loss following administration of intravenous erythromycin lactobionate was investigated using the albino guinea pig. This hearing loss was found, for the first time, to be due to cochlear dysfunction caused by erythromycin administration.The endocochlear potential (EP) and the cochlear microphonics (CM), recorded at the first or second cochlear turn, transiently decreased when erythromycin was administered intravenously at dosages of 100 and 150 mg/kg. The decrease in EP and CM was clearly related to dose. A complete recovery of EP and CM ensued after each erythromycin application. However, perilymphatic perfusion with 3 mM of erythromycin caused an immediate and drastic decrease in CM, while it caused a mild decrease in EP following its initial elevation. The magnitude of the negativity of EP in response to anoxia was small after perilymphatic perfusion, while it remained within the normal range with intravenous application.These findings suggest that intravenously applied erythromycin has a direct effect upon the stria vascularis, while erythromycin applied via the perilymph exerts its potent action predominantly on the hair cells.