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Updated: Apr 4, 2026
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Determination of the toxicity of intravitreal minocycline in rabbit eyes
Khalil Ghasemi Falavarjani1, Arash Pourhabibi1, Kaveh Abri Aghdam1
1a Eye Research Center, Rassoul Akram Hospital, Iran University of Medical Sciences , Tehran , Iran .
Purpose:
To evaluate the retinal toxicity of intravitreal minocycline in rabbit eyes.
Methods:
Intravitreal injection of minocycline with concentrations of 1000, 500, 250, 125 and 62.5 μg in 0.1 ml was performed in 10 New Zealand albino rabbits. Each concentration was injected into two rabbit eyes. For each dose, normal saline was injected in one contralateral eye and the other fellow eye remained non-injected. Electrophysiologic testing was performed before and 4 weeks after injections. The eyes were enucleated 4 weeks after injections and examined using light microscopy.
Results:
The clinical examination was unremarkable after injections. Electroretinography recordings were significantly affected at all doses in at least one of the a- or b-waves of photopic or scotopic responses. Histopathologic examination revealed marked atrophy and loss of integrity in all retinal layers in all minocycline injected eyes. Contralateral eyes were normal.
Conclusion:
In our study, intravitreal minocycline was toxic to the retina in albino rabbits even at a concentration of 62.5 µg/0.1 ml.
Insights
Intravitreal minocycline demonstrated significant retinal toxicity in rabbit eyes, impacting electroretinography and causing retinal damage even at low doses. This suggests minocycline is unsafe for direct injection into the eye.
Area of Science:
- Ophthalmology
- Toxicology
- Retinal Science
Background:
- Minocycline, a tetracycline antibiotic, is explored for potential ophthalmic applications.
- Understanding the safety profile of intravitreal drug delivery is crucial for ocular therapeutics.
Purpose of the Study:
- To assess the retinal toxicity of intravitreal minocycline in a rabbit model.
- To determine the dose-dependent effects of minocycline on retinal function and structure.
Main Methods:
- Intravitreal injections of varying minocycline concentrations (62.5–1000 µg) were administered to New Zealand albino rabbit eyes.
- Electrophysiologic testing (electroretinography) and histopathologic examination were performed before and after injections.
- Control eyes received saline injections or were left non-injected.
Main Results:
- Electroretinography showed significant alterations in a- and b-waves across all tested minocycline concentrations.
- Histopathology revealed severe retinal atrophy and loss of integrity in all minocycline-treated eyes.
- No toxicity was observed in contralateral control eyes.
Conclusions:
- Intravitreal minocycline exhibits significant retinal toxicity in rabbits.
- Retinal damage occurred even at the lowest tested concentration (62.5 µg/0.1 ml).
- These findings indicate minocycline is unsuitable for intravitreal administration due to its ocular toxicity.
