Vol.95 No.7 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 95 No. 7 July 2002
Safety of Antimicrobials Applied in the Middle Ear Cavity
Tetsuo Morizono
(Chikushi Hospital, Fukuoka University)
A literature review of the safety or ototoxicity of antimicrobials applied to the middle ear cavity was performed. Animal experiments indicated ototoxic effects of otic drops used for the treatment of suppurative otitis media as well as some antiseptic solutions used for preoperative sterilization for the middle ear surgery. Clinical experience indicated fewer adverse effects following the use of antimicrobials and antiseptics in the middle ear cavity, although scant but serious side effects have been reported in the literature. The discrepancy of animal experiment and clinical experience is due largely to the anatomical differences of the cochlea, the round window of rodents are very thin and exposed into the middle ear cavity, whereas that of humans is thick and situated deep in the niche, and often covered with a pseudomembrane.
We evaluated the safety of recently marketed eardrops Ofloxacin (OFLX) and Fosfomycin sodium (FOM). Based on the lack of reduction of the compound action potential in guinea pigs, we concluded that there was no ototoxic effect using OFLX or FOM.
Also, the ototoxic effect of a Povidone-Iodine preparation was studied. Full strength solution instilled into the middle ear cavity did not cause sensorineural hearing loss at the 24 hours, indicating that rinsing the middle ear cavity with saline during surgery should prevent ototoxic effects of this product.
Key words : topical antimicrobials, ototoxicity, round window