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Updated: Aug 29, 2026
Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Ocular toxicity of intravitreal trovafloxacin in the pigmented rabbit
Eugene W M Ng1, Myung-Jin Joo, Kah-Guan Au Eong
1Ocular Microbiology Laboratory, The Wilmer Ophthalmological Institute, Baltimore, MD 21287-9121, USA.
Purpose:
Trovafloxacin is an expanded spectrum, newer-generation fluoroquinolone antibiotic with improved Gram-positive and anaerobic activity compared with existing quinolones, while maintaining Gram-negative activity comparable to ciprofloxacin. Given its broad spectrum of activity, trovafloxacin may have potential use for treatment of acute bacterial endophthalmitis. This study examined the toxicity of intravitreally administered trovafloxacin in the pigmented rabbit eye.
Methods:
Doses of trovafloxacin ranging from 12.5 microg to 1000 microg were injected into the mid-vitreous of Dutch Belted rabbit eyes. Clinical examination was performed at 1, 3, and 14 days following injection. Animals were sacrificed and eyes were enucleated 14 days following injection. Light microscopy (LM) and transmission electron microscopy (TEM) studies of the optic nerve head, medullary ray, and inferior retina were performed to determine toxicity.
Results:
At intravitreal doses of 500 microg and less, no toxicity was observed at the ophthalmoscopic or light microscopic level. By TEM, a dose-dependent increase in injury to retinal pigment epithelium, photoreceptors, and nerve fibers in the optic nerve head and medullary ray was observed from 50 microg to 500 microg. No toxicity was noted at doses of 12.5 microg and 25 microg. At doses of 750 microg and above, edema of the medullary ray was noted on ophthalmoscopy. Swelling of the peripapillary medullary ray and necrosis of the inferior retina were evident on LM.
Conclusion:
Intravitreal trovafloxacin doses of 50 microg and higher in the pigmented rabbit eye cause retinal and nerve fiber injury. Intravitreal doses 25 microg and lower appear to be safe, with no evidence of ocular toxicity.
Insights
Intravitreal trovafloxacin at doses of 50 micrograms and higher caused ocular toxicity in rabbit eyes. Doses of 25 micrograms and lower appear safe for treating endophthalmitis.
Area of Science:
- Ophthalmology
- Pharmacology
- Microbiology
Background:
- Trovafloxacin is a newer-generation fluoroquinolone antibiotic with broad-spectrum activity.
- Its potential use for treating acute bacterial endophthalmitis warrants investigation.
- Assessing ocular toxicity is crucial for determining safe therapeutic dosages.
Purpose of the Study:
- To evaluate the toxicity of intravitreally administered trovafloxacin in pigmented rabbit eyes.
- To identify safe dosage levels for potential ophthalmic applications.
Main Methods:
- Dutch Belted rabbits received intravitreal injections of trovafloxacin (12.5–1000 microg).
- Ocular examinations included clinical assessment, light microscopy (LM), and transmission electron microscopy (TEM).
- Toxicity was assessed in the optic nerve head, medullary ray, and retina.
Main Results:
- No toxicity was observed at doses of 25 microg or lower.
- Doses of 50 microg and higher showed dose-dependent retinal pigment epithelium, photoreceptor, and nerve fiber injury via TEM.
- Higher doses (≥750 microg) resulted in medullary ray edema and retinal necrosis.
Conclusions:
- Intravitreal trovafloxacin at 50 microg and above induces ocular toxicity in rabbit eyes.
- Doses of 25 microg and below appear safe, suggesting potential for treating endophthalmitis.
