Ototoxicity of topical ciprofloxacin/dexamethasone otic suspension in a chinchilla animal model.

OBJECTIVE To determine the ototoxic potential of ciprofloxacin/dexamethasone eardrops. METHODS Ventilation tubes were inserted in the ears of 15 chinchillas. One ear was randomized to receive four drops of ciprofloxacin/dexamethasone. A control solution (0.45% NaCl) was applied in the contralateral ear. The eardrops were delivered twice daily for 7 consecutive days. Auditory brain stem response (ABR) measurements were recorded at baseline (post-tympanostomy tube insertion), and on days 4, 8, 15, 22, and 60. RESULTS An initial transient increase of 8.11 dB nHL was noted in the mean thresholds of the experimental ears at day 4. On the last ABR evaluation (day 60), the mean thresholds were 16.33 +/- 6.93 dB nHL in the experimental ears and 13.66 +/- 6.65 dB nHL in the control ears. The difference in the mean thresholds between the experimental and control ears at day 60 was not significant (95% confidence interval, 3.12, -8.02). Scanning electron microscopy demonstrated normal morphology in all experimental ears that were assessed. CONCLUSION Ciprofloxacin/dexamethasone eardrops did not appear ototoxic when used in chinchillas post-ventilation tube insertion.