Effects of Common Ear Drops on Tympanic Membrane Healing in Rats

Objective. Ciprofloxacin 1 dexamethasone ear drops have been associated with higher rates of tympanic membrane perforations than ofloxacin. This was thought to be an effect of the steroid; however, ciprofloxacin (sans steroid) has been found to be more toxic to tympanic membrane fibroblasts than ofloxacin in vitro. This study aimed to compare the effect of these agents on tympanic membrane healing in vivo. Study Design. Controlled animal study. Setting. Academic research laboratory. Methods. Perforations were created in 54 rats with a carbon dioxide laser. Rats were randomized to 6 groups (9/group), with 1 ear receiving ofloxacin, ciprofloxacin, dexamethasone, ofloxacin 1 dexamethasone, ciprofloxacin 1 dexamethasone, or neomycin, and the contralateral ear receiving saline twice daily for 10 days. Healing was assessed over 40 days. Results. Ofloxacin did not delay healing relative to saline. All other treatments delayed healing relative to ofloxacin at day 10 (P < .0001). Dexamethasone and ofloxacin 1 dexamethasone delayed healing up to day 14 (P < .0001). Neomycin and ciprofloxacin 1 dexamethasone further delayed healing up to day 28 (P = .009) and day 35 (P = .043), respectively. All eardrums healed by day 10 with ofloxacin, day 20 with ciprofloxacin, day 28 for dexamethasone, and day 35 for ofloxacin 1 dexamethasone. At day 40, 2 of 9 ciprofloxacin 1 dexamethasone-treated eardrums had not healed. All saline-treated eardrums in the ofloxacin, ciprofloxacin, dexamethasone, and ofloxacin 1 dexamethasone groups were healed by day 14, but this was delayed to day 20 in the ciprofloxacin 1 dexamethasone group (P = .007). Conclusions. Ototopical quinolones delay rat tympanic membrane healing in a drug-specific manner, with ciprofloxacin having a greater impact than ofloxacin. This effect is potentiated by steroids.