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Updated: Aug 18, 2026
Trans-Tympanic Drug Delivery for the Treatment of Ototoxicity
Published on: March 16, 2018
Otologic effects of topical mitomycin C: phase I-evaluation of ototoxicity
Seilesh C Babu1, Jack M Kartush, Aftab Patni
1Michigan Ear Institute, Farmington Hills, Wayne State University, Detroit, Michigan, USA.
Hypothesis:
To determine ototoxicity of topical mitomycin C when placed in the middle ear at varying concentrations.
Background:
Despite meticulous surgical technique and diligent postoperative care, some patients develop excessive scar and granulation tissue in the middle ear or mastoid cavity. Poor wound healing may result in infection, tympanic membrane perforation, or conductive hearing loss, which may necessitate further surgery. Use of topical mitomycin C in the ear may be beneficial in reducing scar and granulation tissue formation. This phase of the study was developed to determine the safety of topical mitomycin C in the rat model relative to ototoxicity.
Methods:
Twelve Sprague-Dawley rats were evaluated with auditory brainstem response testing before and after treatments. Topical mitomycin C was injected in the middle ear of the right ear of eight animals. Varying concentrations of 0.125 to 0.5 mg/ml were used. Saline was injected in the left ear of each animal to serve as a control. Four separate animals were evaluated with placement of topical mitomycin C on Gelfoam into the middle ear. In two animals, Gelfoam was placed in the middle ear for 1 minute and then removed. In two animals, Gelfoam was placed in the middle ear and left in place. Auditory brainstem response testing was performed at 4 weeks and at 8 weeks.
Results:
Using a high concentration of mitomycin C (>0.25 mg/ml) resulted in ototoxicity, with an increase in the auditory brainstem response threshold at 4 weeks and at 8 weeks. At low concentrations (<0.20 mg/ml), no change in auditory brainstem response threshold was noted. Animals treated with Gelfoam soaked in mitomycin C showed no change in auditory brainstem response threshold.
Conclusion:
The results of this study indicate that topical mitomycin C on Gelfoam applied in the middle ear appears safe when low concentrations are used, even in the rat, which has a higher susceptibility to gentamycin toxicity than humans. Higher concentrations may lead to ototoxicity based on changes in Wave V on auditory brainstem response. This treatment may prove to be an important option for patients suffering from chronic granulation tissue or scar tissue in the external or middle ear.
Insights
Topical mitomycin C in the middle ear is safe at low concentrations, but higher doses may cause ototoxicity. This study in rats suggests potential benefits for scar tissue reduction.
Area of Science:
- Ototoxicity research
- Pharmacology of topical agents
- Middle ear wound healing
Background:
- Scar and granulation tissue in the middle ear can lead to complications like infection and hearing loss.
- Topical mitomycin C may reduce scar tissue formation.
- This study assesses the ototoxicity of topical mitomycin C in a rat model.
Purpose of the Study:
- To determine the ototoxicity of topical mitomycin C in the middle ear at varying concentrations.
- To evaluate the safety of topical mitomycin C for reducing scar tissue in the ear.
Main Methods:
- Auditory brainstem response (ABR) testing was performed on Sprague-Dawley rats.
- Topical mitomycin C was administered to the middle ear at concentrations ranging from 0.125 to 0.5 mg/ml.
- Control groups received saline or Gelfoam soaked with mitomycin C.
Main Results:
- High concentrations of mitomycin C (>0.25 mg/ml) led to ototoxicity, indicated by increased ABR thresholds.
- Low concentrations (<0.20 mg/ml) and mitomycin C on Gelfoam showed no significant ototoxicity.
- ABR thresholds were monitored at 4 and 8 weeks post-treatment.
Conclusions:
- Topical mitomycin C appears safe for middle ear application at low concentrations, even in rats.
- Higher concentrations of mitomycin C may cause ototoxicity.
- This agent shows promise for managing chronic granulation or scar tissue in ear surgeries.
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