Commercial Quinolone Ear Drops Cause Perforations in Intact Rat Tympanic Membranes.

HYPOTHESIS

Commercial quinolone ear drops may promote the development of perforations (TMPs) in intact tympanic membrane (TMs).

BACKGROUND

Quinolone ear drops have been associated with TMPs after myringotomy +/- tube placement in a drug-specific manner and potentiation by steroids.

METHODS

Rats were randomized to six groups (10/group), with one ear receiving otic instillation of dexamethasone, ofloxacin, ciprofloxacin, ofloxacin + dexamethasone, ciprofloxacin + dexamethasone, or neomycin + polymyxin + hydrocortisone-all commercial formulations and at standard clinical concentrations-and the contralateral ear receiving saline, twice daily for 10 days. TMs were assessed over 42 days.

RESULTS

No TMPs were seen in ears treated with saline, dexamethasone, or neomycin. At day 10, TMPs were seen in one of 10 ofloxacin- and three of 10 ciprofloxacin + dexamethasone-treated ears (p = 0.038). At day 14, the ofloxacin TMP healed. In contrast, the three ciprofloxacin + dexamethasone TMPs remained and one new TMP developed in this group. A ciprofloxacin and an ofloxacin + dexamethasone-treated ears also had TMPs (p = 0.023). By day 21, the ofloxacin + dexamethasone TMP and two of four of the ciprofloxacin + dexamethasone TMPs healed but two new TMPs were seen in ciprofloxacin + dexamethasone ears (p = 0.0006). At day 28, 1 of 10 ciprofloxacin and 4 of 10 ciprofloxacin + dexamethasone-treated ears had TMPs (p = 0.0006). By day 35, only one ciprofloxacin + dexamethasone had TMP (p = 0.42). All TMPS were healed at day 42.

CONCLUSIONS

Application of commercial quinolone ear drops can cause TMPs in intact TMs. This effect appears to be drug-specific and potentiated by steroids.