title: Plasma and ear tissue concentrations of enrofloxacin and its metabolite ciprofloxacin in dogs with chronic end-stage otitis externa after intravenous administration of enrofloxacin.
abstract: The purpose of this study was to measure the concentrations of enrofloxacin and its metabolite ciprofloxacin following intravenous administration of enrofloxacin in the plasma and ear tissue of dogs with chronic end-stage otitis undergoing a total ear canal ablation and lateral bulla osteotomy. The goals were to determine the relationship between the dose of enrofloxacin and the concentrations of enrofloxacin and ciprofloxacin, and determine appropriate doses of enrofloxacin for treatment of chronic otitis externa and media. Thirty dogs were randomized to an enrofloxacin-treatment group (5, 10, 15 or 20 mg kg(-1)) or control group (no enrofloxacin). After surgical removal, ear tissue samples (skin, vertical ear canal, horizontal ear canal, middle ear) and a blood sample were collected. Concentrations of enrofloxacin and ciprofloxacin in the plasma and ear tissue were measured by high performance liquid chromatography. Repeated measures models were applied to log-transformed data to assess dosing trends and Pearson correlations were calculated to assess concentration associations. Ear tissue concentrations of enrofloxacin and ciprofloxacin were significantly (P < 0.05) higher than plasma concentrations. Each 5 mg kg(-1 )increase in the dose of enrofloxacin resulted in a 72% and 37% increase in enrofloxacin and ciprofloxacin concentrations, respectively. For bacteria with an minimal inhibitory concentration of 0.12-0.15 or less, 0.19-0.24, 0.31-0.39 and 0.51-0.64 microg mL(-1), enrofloxacin should be dosed at 5, 10, 15 and 20 mg kg(-1), respectively. Treatment with enrofloxacin would not be recommended for a bacterial organism intermediate or resistant in susceptibility to enrofloxacin since appropriate levels of enrofloxacin would not be attained.
authors.affiliation: Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA. cole.143@osu.edu
authors.forename: Lynette K
authors.initials: LK
authors.lastname: Cole
authors.forename: Mark G
authors.initials: MG
authors.lastname: Papich
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Kwochka
authors.forename: Andrew
authors.initials: A
authors.lastname: Hillier
authors.forename: Daniel D
authors.initials: DD
authors.lastname: Smeak
authors.forename: Amy M
authors.initials: AM
authors.lastname: Lehman
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D002908:Chronic Disease; D002939:Ciprofloxacin / Q000097:blood / Q000378:metabolism*; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004424:Ear Canal; D000077422:Enrofloxacin; D005260:Female; D024841:Fluoroquinolones / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D007275:Injections, Intravenous; D008297:Male; D010032:Otitis Externa / Q000188:drug therapy / Q000662:veterinary*; D012867:Skin; D014018:Tissue Distribution
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D000077422:Enrofloxacin; D002939:Ciprofloxacin