Ototoxicity of Topical Castellani Solution and Boric Acid in Alcohol: an Experimental Study on Rats

The aim of this study is to determine the ototoxicities of boric acid in alcohol (BAA) and Castellani solutions by means of distortion product otoacoustic emission (DPOAE). A total of 28 rats were randomly divided into four groups, each group consisting of 7 animals. Then, 0.1 mL Castellani solution, 0.1 mL BAA (4% boric acid solution prepared with 60% alcohol), 0.2 mL (40 mg/mL) gentamicin and 0.2 mL saline were dropped to right outer ear canals of rats in groups 1, 2, 3 and 4 respectively, twice a day, for 14 days. DPOAE values obtained on days 0 and 14 were statistically compared for the values obtained at 750–8000 Hz frequencies. A statistically significant decrease was found on day 14 compared to day 0 values in Castellani group at all frequencies (p < 0.05). In BAA group, there was a statistically significant decrease between frequencies 1500 and 8000 Hz on day 14 (p < 0.05).We found that Castellani and BAA were ototoxic. BAA and Castellani solutions should be avoided in patients with tympanic membrane perforations, ventilation tubes and open mastoid cavities.