Ototoxicity of triethanolamine polypeptide (cerumenex) in the chinchilla

The use of earwax softeners and cerumenolytics to unblock the external auditory canal is increasing. Although reports on their effectiveness are available, data about their effect on hearing are limited.

To assess the effect of ototopic triethanolamine polypeptide oleate condensate 10% (Cerumenex) on hearing.

Prospective, randomized, controlled trial in a chinchilla animal model.

Tympanostomy tubes were inserted in five chinchillas, and hearing was assessed with distortion product otoacoustic emissions (DPOAE) between 1 and 9 kHz prior to application and at days 1, 4, 30, and 100 postototopic application of Cerumenex. One ear received Cerumenex; the other ear served as control. Postmortem scanning electron microscopy was performed to assess the cochlear hair cells.

A reduction in the mean DPOAE signal was shown in the ears treated with Cerumenex from the first day after treatment and throughout the study. Almost all tested frequencies were affected. Swelling, crusting, and fluid were observed in four of the five experimental ears. One animal also developed facial paralysis in the experimental side. Electron microscopy showed damage of the outer and inner hair cells in the Cerumenex-treated ears.

In the chinchilla, when a tympanic perforation is present, Cerumenex causes a reduction in DPOAE signal and damage to the cochlear hair cells. Caution should be observed when prescribing this agent if the status of the tympanic membrane is unknown. Furthermore, its use without medical prescription should be discouraged because of the risk of ototoxicity and severe inflammatory reaction.