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Ototoxicity of topically applied gentamicin using a statistical analysis of electrophysiological measurement
Abstract:
Ototoxicity of topically applied gentamicin was studied in guinea pigs. 0.3% gentamicin was instilled in one side of the middle ear cavity and Ringer's solution was instilled in the other side, and the difference in the cochlear microphonics measured with the round window electrode was analysed statistically. Instillation of Ringer's solution in the middle ear cavity for 1 day did not cause any significant sensorineural hearing loss, but on the 3rd day of instillation significantly reduced responses were observed, compared with the responses from non-treated ears, followed by a partial recovery starting on the 4th day. When gentamicin 0.3% was instilled into the middle ear cavity, significant deafness occurred 24 hours later, and highly significant deafness on the 2nd and 3rd day. The usage of gentamicin ear drops of the current formula should be discouraged until a better formula is provided.
Insights
Topical gentamicin causes significant ototoxicity in guinea pigs, leading to profound hearing loss. Current gentamicin ear drop formulations should be avoided due to this risk.
Area of Science:
- Ototoxicity and audiology research
- Pharmacological effects on the inner ear
Background:
- Topical gentamicin is used for ear infections.
- Potential risks of ototoxicity require investigation.
Purpose of the Study:
- To evaluate the ototoxicity of topical gentamicin in a guinea pig model.
- To assess the impact of gentamicin on cochlear function.
Main Methods:
- Guinea pigs received 0.3% gentamicin or Ringer's solution in the middle ear.
- Cochlear microphonics were measured via round window electrode.
- Statistical analysis compared treated and non-treated ears.
Main Results:
- Ringer's solution caused temporary hearing reduction by day 3.
- Gentamicin induced significant deafness within 24 hours.
- Profound, persistent hearing loss was observed with gentamicin treatment.
Conclusions:
- Topical gentamicin exhibits significant ototoxicity.
- Current gentamicin ear drop formulations are potentially harmful.
- Development of safer formulations is recommended.
