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An in vitro analysis of aminoglycoside corneal epithelial toxicity
J H Lass1, R J Mack, P S Imperia
1Division of Ophthalmology, University Hospitals of Cleveland, OH.
Abstract:
We evaluated the cytotoxicity of four aminoglycoside agents (neomycin, gentamicin, tobramycin, and amikacin) using an in vitro confluent rabbit corneal epithelial cell culture model. Primary corneal epithelial cell cultures were established and cells replated at 2 x 10(4) cells/2 cm2 well. After 48 hours either vehicle or an antibiotic was added at varying concentrations, each for 5, 30, or 60 minutes. 3H-thymidine was added immediately after drug removal and incorporation was measured 8 hours after drug or vehicle exposure. Comparisons of each drug to vehicle were expressed as % inhibition of control culture values. At the 5-minute exposure time tobramycin and amikacin showed no significant inhibition at any concentration, whereas neomycin and gentamicin showed significant inhibition at 6 mg/ml and 3.5 mg/ml or greater concentrations, respectively (p less than 0.05). At 30- and 60-minute exposure times all agents demonstrated significant inhibition at all tested concentrations in a non-dose dependent fashion (p less than 0.05). These in vitro data corroborate the animal and limited clinical data available for the aminoglycosides. Based on these toxicity profiles, tobramycin appears to be the topical agent of choice in the treatment of susceptible bacterial keratitis.
Insights
Tobramycin and amikacin showed minimal cytotoxicity in rabbit corneal cells, unlike neomycin and gentamicin. Tobramycin is recommended for bacterial keratitis due to its favorable toxicity profile.
Area of Science:
- Ophthalmology
- Pharmacology
- Toxicology
Background:
- Aminoglycosides are commonly used antibiotics for bacterial infections.
- Corneal epithelial cell toxicity is a concern for topical ophthalmic medications.
- Understanding the in vitro cytotoxicity of aminoglycosides is crucial for clinical application.
Purpose of the Study:
- To evaluate and compare the in vitro cytotoxicity of four aminoglycoside agents: neomycin, gentamicin, tobramycin, and amikacin.
- To determine the impact of exposure time and concentration on aminoglycoside-induced corneal epithelial cell damage.
- To identify the most suitable topical aminoglycoside for treating bacterial keratitis based on toxicity profiles.
Main Methods:
- Utilized an in vitro confluent rabbit corneal epithelial cell culture model.
- Exposed cells to varying concentrations of aminoglycosides (neomycin, gentamicin, tobramycin, amikacin) for 5, 30, or 60 minutes.
- Assessed cytotoxicity by measuring 3H-thymidine incorporation inhibition post-drug exposure.
Main Results:
- At 5-minute exposure, tobramycin and amikacin showed no significant cytotoxicity.
- Neomycin and gentamicin exhibited significant cytotoxicity at concentrations of 6 mg/ml and 3.5 mg/ml, respectively.
- After 30 and 60 minutes, all tested aminoglycosides demonstrated significant, non-dose-dependent cytotoxicity.
Conclusions:
- Tobramycin and amikacin present a lower in vitro cytotoxicity risk compared to neomycin and gentamicin.
- Prolonged exposure to aminoglycosides increases corneal epithelial cell toxicity.
- Tobramycin is suggested as the preferred topical agent for bacterial keratitis treatment due to its safety profile.