Related Experiment Video
Updated: May 16, 2026
Ocular Therapeutic Delivery and Advanced Tissue Retrieval in Adult Rats
Published on: May 23, 2025
Ototopic applications of povidone iodine/dexamethasone in the rat
Karen Pawlowski1, Elena Koulich, Charles G Wright
1Department of Otolaryngology-Head and Neck Surgery/Biomedical Engineering, UT Southwestern Medical Center, Dallas, Texas 75390-9035, USA. pawlowski@utsouthwestern.edu
Hypothesis:
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.
Conclusion:
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.
Insights
Topical povidone iodine (PI) and dexamethasone (Dex) ear drops did not cause hearing or balance problems in rats. This study suggests PI/Dex formulations are safe for treating ear infections.
Area of Science:
- Otolaryngology
- Pharmacology
- Toxicology
Background:
- Otitis externa (OE) and acute otitis media (AOM) are common ear infections treated with antibiotics.
- Topical treatments can reduce systemic antibiotic exposure.
- Povidone iodine (PI) and dexamethasone (Dex) formulations offer antimicrobial and anti-inflammatory benefits.
Purpose of the Study:
- To evaluate the ototoxicity of repeated topical applications of low-concentration povidone iodine (PI) combined with dexamethasone (Dex) in rats.
- To assess the safety of PI/Dex formulations for treating OE and AOM.
Main Methods:
- Rats underwent tympanostomy with ventilation tube insertion.
- 1% or 2% PI with 0.1% Dex were applied for 7 days.
- Auditory brainstem response (ABR) and histologic analysis assessed hearing and ear structures.
Main Results:
- Neither PI/Dex formulation caused significant pathologic changes in middle or inner ear structures.
- No adverse effects on hearing function or equilibrium were observed.
- The treatments were found to be safe for repeated application.
Conclusions:
- Repeated topical application of PI/Dex formulations through ventilation tubes is safe in rats.
- These formulations do not induce ototoxic changes, preserving hearing and equilibrium.
- PI/Dex represents a potentially safe and effective treatment for OE and AOM.
