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H.F. Edelhauser, W. Brooks, D. Ghate, D.H. Geroski, D. DeVore, R.A. Eiferman; Scleral Permeability of Dexamethasone–Fluorescein in a Collagen Gel Vehicle . Invest. Ophthalmol. Vis. Sci. 2005;46(13):480.
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© ARVO (1962-2015); The Authors (2016-present)
Intravitreal and posterior subtenon steroid injections are used to treat a variety of posterior segment conditions. Soluble collagen inserts impregnated with drugs have been used for localized drug delivery to the eye and other organs. A collagen gel impregnated with steroid should result in sustained drug delivery localized to the posterior segment and with the potential of easy removal should any complications arise. Purpose:To determine scleral permeability and continuous release of dexamethasone–fluorescein (DF) from high and low collagen gels and collagen film. Methods: Sections of sclera excised from moist–chamber stored human globes from the Georgia Eye Bank were mounted in a perfusion chamber. The pressure and temperature were maintained at 15 mm Hg and 36oC, respectively. A small depot (200 µL) of high or low collagen gel, or a 7.0 mm button of collagen film and 100 µL of BSS, was added to the episclera in a donor chamber. On the choroidal side of the sclera, BSS was perfused at a starting rate of 2.00 mL/min. and a running rate of 0.03 mL/min. Perfusate samples were collected in a fraction collector every half hour for a period of 24 hours. Concentrations of DF were measured using a fluorometer. Transscleral permeability Flux(µg/sec/cm2) was calculated using these concentrations. Results: Flux(µg/sec/cm2) for DF low collagen gel (20% collagen) was (Mean ± SD) 6.21 ± 0.87x10–04 (n=2), and for high collagen gel (40% collagen) was 6.39 ± 1.8x10–03 (n=3). Flux(µg/sec/cm2) for the 10–3.5 M collagen film was 7.39 ± 2.26x10–04 (n=4). Both gels and the collagen film showed a release over a 24 hour period. Conclusions:A continuous slow release of DF occurs with both high, low and film form of the collagen gel with the highest scleral diffusion occurring with the high collagen gel.
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