The Study Of Aciclovir Ophthalmic Gel

As one of the important fields of controlled release, ophthalmic drug delivery has received extensive interests during the last two decades. The sensitivity and protection mechanisms of the eye promote more effective drug delivery systems with better compliancy to be developed, however, the applications of numerous pharmaceutical methods are limited simultaneously, which presents great challenge in designing ophthalmic dosage forms. In this dissertation, Aciclovir was selected as model drug, then an ophthalmic sustained-release gel of ACV was developed and evaluated in vitro and in vivo. Three main sections were included in this paper:1. The study on the solubilities and partition coefficients of drugThe results showed that the solubilities of ACV was dependent on pH value, and the partition coefficients were lower, and the main rate-limiting barrier was corneal epithelium. In order to increase the transcorneal influx of drugs, penetration enhancers were needed to employ.2. The study on ophthalmic sustained-release gel of ACVa). The permeability of ACV across isolated rabbit cornea was measured using in vitro method under various penetration enhancers. The diffusion behaviors of ACV across isolated rabbit cornea possessed zero-order kinetic characteristic. An apparent permeation coefficient of 1.43×10^-6 cm·s^-1 was found without enhancers. 0.05%Azone and 2% HP-β-CD improved the apparent permeability of ACV as much as 1.70 and 1.72, respectively. However, 1% poloxamer (F127) and 0.5%EDTA did not improve the apparent permeability of ACV. All enhancers did not significantly change the transcorneal lag time of ACV. The irritancy of poloxamer and Azone was observed.b). The results of in vitro release studies showed that the ACV gel based 0.5% HPMC K4M and 0.2% Carbopol 980 provided sustained release of the drug over an 8-h period in...