title: Ototopic applications of povidone iodine/dexamethasone in the rat.
abstract: OBJECTIVE
  Repeated applications of low-concentration povidone iodine (PI) combined with dexamethasone (Dex) through a tympanic membrane ventilation tube will not cause ototoxic changes in the rat.
  
  
  BACKGROUND
  Otitis externa (OE) and acute otitis media (AOM) are 2 of the most common otologic disorders requiring outpatient antibiotic treatment. The development of topical treatments that are easy to administer would help to limit systemic exposure to antibiotics in these patients. Topical formulations containing Dex and low-dose PI were designed to provide both antimicrobial and anti-inflammatory effects for the treatment of OE and AOM. Treatment with PI alone has shown mixed results in studies designed to determine PI. Low concentrations of PI combined with Dex should yield less ototoxicity while maintaining effectiveness.
  
  
  METHODS
  We performed tympanostomies on rats, inserting a ventilation tube to administer 1% or 2% PI, plus 0.1% Dex over a period of 7 days. Hearing was accessed via auditory brainstem response (ABR) testing over the duration of the study and histologic analysis was performed 15 days after the initial application to determine the effect of administration of PI/Dex on middle and inner ear structures.
  
  
  CONCLUSIONS
  The preparations used in the present investigation were formulated to allow repeated applications to both the external and middle ear, without risk to hearing or equilibrium. Neither of the PI/Dex formulations tested caused pathologic changes in the ear that significantly affected equilibrium, hearing function or morphology.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery/Biomedical Engineering, UT Southwestern Medical Center, Dallas, Texas 75390-9035, USA. pawlowski@utsouthwestern.edu
authors.forename: Karen
authors.initials: K
authors.lastname: Pawlowski
authors.forename: Elena
authors.initials: E
authors.lastname: Koulich
authors.forename: Charles G
authors.initials: CG
authors.lastname: Wright
authors.forename: Peter
authors.initials: P
authors.lastname: Roland
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D003907:Dexamethasone / Q000008:administration & dosage* / Q000627:therapeutic use; D016503:Drug Delivery Systems; D008297:Male; D010032:Otitis Externa / Q000188:drug therapy*; D010033:Otitis Media / Q000188:drug therapy*; D011206:Povidone-Iodine / Q000008:administration & dosage* / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D014432:Tympanic Membrane / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D003907:Dexamethasone; D011206:Povidone-Iodine