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M. Yamaguchi, K. Ueda, A. Isowaki, A. Ohtori, H. Takeuchi, N. Ohguro, K. Tojo; Analysis of Extraocular Behavior of Mucoadhesive Chitosan–Coated Emulsion . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5090.
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© ARVO (1962-2015); The Authors (2016-present)
Chitosan–coated ophthalmic emulsions (CE) were reported to improve the bioavailability of drug after instillation due to prolonged residence time of drug in tear by mucoadhesive effect of positively charged chitosan onto conjunctiva. However, pharmacokinetic analysis of CE in tear has not been elucidated yet. In this study, we have evaluated the distribution behavior of CE in extraocular tissues by visual analysis using a confocal laser scanning microscopy. The extraocular profiles for elimination were then analyzed by the side–capacity–parallel–flow (SCPF) model.
CE and non–coated emulsions (NE) containing a fluorescent dye were instilled into rabbit eyes. The eyes were excised after instillation at 1 hour, and the conjunctiva and cornea were collected. Distribution of these emulsions in extraocular tissues was evaluated by a confocal laser scanning microscopy. CE and NE containing indomethacin as a model drug was also instilled into rabbit eyes, and the tear fluid was then collected. The drug concentration in the tear was measured by HPLC. The elimination profile of the drug in tear was analyzed using SCPF model.
Results and Discussion: :
Fluorescent distribution for these emulsions was clearly observed by a confocal laser scanning microscopy. Fluorescence of CE in conjunctiva was more intensive than that of NE. We, therefore, visually confirmed distribution of CE in conjunctiva. In the tear fluid, the drug level of CE was higher than that of NE. These elimination profiles were well described by the SCPF model, and the model parameters, parallel flow ratio α, side flow rate ß and side–capacity volume ration γ, were also evaluated. ß and γ were almost the same for these emulsions. However, α of CE was smaller than that of NE. These values of parameters suggest that CE might be subject to stay longer in conjunctiva than NE.
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