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Kongnara Papangkorn, Donald Mix, Charlotte Butler, David J. Knauss, John W. Higuchi, Balbir Brar, William I. Higuchi; A Topical Ocular Toxicity Study of Dexamethasone Sodium Phosphate Formulations Administered with Visulex-p in Rabbits. Invest. Ophthalmol. Vis. Sci. 2012;53(14):478.
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To assess the ocular tolerability of Visulex-p (Vp) containing dexamethasone sodium phosphate (DSP) following daily dosing for 7 days and weekly dosing for 12 weeks in New Zealand white rabbits.
Twenty-one 5-6 months old rabbits were assigned to seven groups according to Table 1. Vp loaded with 250 ul of the test formulation was applied to the right eye. Vp was then removed at the end of the application. The ocular examinations, with an indirect ophthalmoscope, modified McDonald-Shadduck scoring, and fluorescein staining were completed at pre-, post-, and at selected time-points post-dose. The body weight was recorded at baseline and during the study. After the final observation, animals were sacrificed and the eyes were collected for histological examination for any signs of inflammation, including edema/congestion (conjunctiva, ciliary body, cornea), inflammatory cell infiltration (conjunctiva, cornea, anterior chamber, trabecular meshwork, iris, ciliary body), and neovascularization of cornea.
Ocular findings are summarized in Table 1. Conjunctival injection and chemosis were observed right after dosing in all groups, with severity increasing with dosing concentrations. Resolution was observed within the 1-7 days after each application. At doses of 8% and higher, there was a longer time to resolution with continued weekly treatment. Weight loss occurred with 15% and 25% DSP. No corneal damage was seen at any of the dose groups. No ocular findings were observed in histopathology.
Vp containing 4% and 8% DSP formulation is well tolerated in rabbit for 7 days of daily dosing and over a 3 month period of weekly dosing. Although Vp containing 8% and 15% DSP formulation treatments showed an accumulation of irritation scores over 3 months, there were no signs of irreversible ocular tissue damage in any of the rabbits.
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