Determination of ototoxicity of common otic drops using isolated cochlear outer hair cells

Objectives. Otic drops are commonly used not only for otitis externa, but a lso for otorrhea in the presence of tympanostomy tubes or tympanic membrane perforations. Many studies have demonstrated the ototoxicity of common oti c preparations such as Cortisporin (R) otic drops (Monarch Pharmaceuticals, Bristol, TN). The purpose of this study was to assess the relative ototoxi city of common otic preparations by direct exposure to isolated cochlear ou ter hair cells (OHCs). Methods: OHCs from adult chinchilla cochlea were exp osed to standard bathing solution (control), acetic acid, Acetasol HC (R) ( Alpharma USPD Inc., Baltimore, MD), Gentacidin (R) (CIBA Vision Ophthalmics , Atlanta, GA), and Tobradex (R) (Alcon, Fort Worth, TV. The cells were obs erved using an inverted microscope, and the images were recorded in digital still-frame and video, and analyzed on the Image Pro-Plus 3.0 program (Med ia Cybernetics, Silver Spring, MD). Results and Conclusions. As measured by time to cell death and change in morphology of OHCs, acetic acid with or w ithout hydrocortisone was most toxic to OHCs. Cortisporin was more cytotoxi c than gentamicin and Tobradex.