Experimental uveitis can be maintained in rabbits for a period of six weeks after a safe sensitization method

Intra-vitreal injection of methotrexate in experimental endotoxin-induced uveitis in rabbit

Uveitis is a major cause of vision loss. Methotrexate (MTX) has been widely used in uveitis due to its relatively safe profile. The purpose of this study was to evaluate the effects of two different dosages of MTX via intra-vitreal administration for treatment of endotoxin induced uveitis (EIU) in an experimental model. Thirty-five healthy rabbits were randomly divided into four groups and all animals were tolerated intra-vitreal injections. The first group received normal saline (NS), the second group received normal saline plus Salmonella typhimurium lipopolysaccharide endotoxin (LPS), (NS+LPS), the third group received 400 μg MTX plus LPS (LPS+MTX 400) and the fourth group received 800 μg MTX plus LPS (LPS+MTX 800). Intra-ocular inflammation was evaluated by clinical examination scoring during 7 post-injection days and histopathological examination at the end of study. Kruskal-Wallis and Mann-Whitney U tests were used to compare the histopathological and clinical scores. According to the clinical examinations, all groups demonstrated higher uveitis score than group 1 on first post-injection day. Also, groups 2 and 3 showed greater uveitis score than group 4. On the third, fifth and seventh post-injection days, clinical uveitis score in groups 2, 3 and 4 was significantly higher than group 1. The mean histopathological inflammation intensity scores in groups 2, 3 and 4 were significantly higher than group 1. Single intra-vitreal injection of 400 μg and 800 μg of MTX did not show significant anti-inflammatory effects on EIU in rabbits.

Noninvasive Ocular Drug Delivery System of Dexamethasone Sodium Phosphate in the Treatment of Experimental Uveitis Rabbit

PURPOSE

To investigate the efficacy and safety of dexamethasone sodium phosphate administered through Visulex system (DSP-Visulex) in treating experimental uveitis.

METHODS

Uveitis was induced in rabbits by subcutaneous injections of complete Freund's adjuvant and an intravitreal injection of H37RA antigen. After induction, the animals of the control group received no treatment and the others received various treatment regimens of DSP-Visulex. Each regimen was different in DSP strength (4%, 8%, and 15%), application time, or treatment frequency. Efficacy and safety of DSP-Visulex were evaluated by ophthalmic observations and histopathological examinations for ocular inflammations and pathology.

RESULTS

The control group exhibited panuveitis with significant inflammation in the vitreous, choroid, and retina, but less in the conjunctiva, cornea, and anterior chamber. The uveitis occurred within 24 h after induction and persisted throughout the study in the control group. All treatments showed some reduction in inflammation in the vitreous, choroid, and retina. The higher dose regimens generally showed more rapid and higher degree of resolution than the lower dose regimens. The posterior eye tissues of the 15% and 8% DSP-Visulex appeared normal with minimal or no inflammation, whereas the untreated eye and the 4% DSP-Visulex eyes showed minimal response.

CONCLUSIONS

All DSP-Visulex regimens suppressed the signs of inflammation and were well tolerated over the course of a 29-day study. The 8% and 15% DSP-Visulex treatment regimens were safe and efficacious for anterior, intermediate, and posterior uveitis. On the other hand, the 4% DSP-Visulex regimen may only be considered for anterior and intermediate uveitis.