title: Ototoxicity assessment of a gentamicin sulfate otic preparation in dogs.
abstract: Vestibulotoxic and ototoxic effects often are seen after long-term, high-dose systemic treatment with gentamicin, but toxic effects after topical use have not been reported in animals, to the authors' knowledge. Vestibular and auditory effects of twice daily otic gentamicin treatment for 21 days were evaluated in 10 dogs with intact tympanic membranes and in the same 10 dogs after experimental bilateral myringotomy. Each dog served as its own control; 7 drops of gentamicin sulfate (3 mg/ml in a buffered aqueous vehicle) were placed in 1 ear, and 7 drops of vehicle were placed in the opposite ear. Treatment and control ears were reversed after myringotomy. Vestibular function was evaluated daily by neurologic examination and behavioral assessment. Auditory function was evaluated twice weekly by determination of brain stem auditory evoked potentials. Gentamicin sulfate placed in the ear of clinically normal dogs with intact or ruptured tympanic membranes, in the quantities used in this study, did not induce detectable alteration of cochlear or vestibular function. Serum gentamicin concentration after 21 days of treatment was detectable in only 2 dogs and was an order of magnitude below documented toxic concentrations.
authors.affiliation: Department of Veterinary Physiology, Pharmacology, and Toxicology, School of Veterinary Medicine, Lousiana State University, Baton Rouge 70803, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Strain
authors.forename: S R
authors.initials: SR
authors.lastname: Merchant
authors.forename: T M
authors.initials: TM
authors.lastname: Neer
authors.forename: B L
authors.initials: BL
authors.lastname: Tedford
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000502:physiology; D004285:Dogs; D005072:Evoked Potentials, Auditory / Q000187:drug effects*; D007839:Functional Laterality; D005839:Gentamicins / Q000097:blood / Q000493:pharmacokinetics / Q000633:toxicity*; D006320:Hearing Tests / Q000662:veterinary*; D012016:Reference Values; D012044:Regression Analysis; D013997:Time Factors; D014432:Tympanic Membrane / Q000502:physiology*; D014722:Vestibule, Labyrinth / Q000187:drug effects* / Q000473:pathology / Q000502:physiology
chemical_list: D005839:Gentamicins