Effects of middle ear application of cipro HC otic suspension in an animal model

The objective of this study was to examine whether ciprofloxacin-containing otic drops (Cipro HC Otic Suspension; 0.2% ciprofloxacin, 0.1% hydrocortisone; Alcon, Ontario, Canada) are cochleotoxic in the chinchilla animal model. Five chinchillas in total underwent these studies. Pretreatment distortion-product otoacoustic emissions (DPOAEs) were measured in each ear, followed by a random injection of Cipro to one ear and normal saline to the other. Injections consisted of 0.2 mL into the middle ear cavity (bulla) for 5 consecutive days. Post-treatment DPOAEs and auditory brainstem responses were measured at 1 month, and cochlear hair cell integrity was assessed by scanning electron microscopy (SEM). All animals had normal pretreatment DPOAEs. One month after Cipro instillation, DPOAE levels decreased in three of the animals. No significant change was seen in the ears treated with saline. On SEM examination, the integrity of the stereocilia of the inner and outer hair cells demonstrated no histologic evidence of significant cochlear damage. The finding of reduced DPOAEs suggests a mild local middle ear inflammation caused by the ciprofloxacin or some other component or property of Cipro.