الفهرس 
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Abstract
The ocular absorption of drugs is highly hindered by eye protective mechanisms, corneal barrier, and by other factors, for example, drainage of the instilled solutions, lacrimation, and tear turnover. An increase in the residence time of eye medications would enhance therapeutic benefits. The drainage rate and the residence time are affected by the viscosity of the applied ophthalmic preparation. The increase in the viscosity of the ophthalmic preparations has been utilized in purpose of increasing the ocular contact time, decreasing the drainage rate, and improving the drug bioavailability. Improvement of the release of water-insoluble drugs is one of the most challenging issues of drug development. Complexation with cyclodextrins (CyDs) has been reported to enhance solubility, stability, and bioavailability of poorly water-soluble drugs. Also, use of sustained drug delivery systems to provide controlled and continuous delivery of water-soluble drugs has been widely investigated to increase the precorneal residence time, enhance the ocular bioavailability, and reduce dosing frequency. In the light of the above-mentioned facts, the aims of present thesis were to develop and evaluate some ophthalmic gels and ocuserts containing CyD complexes of the hydrophobic loteprednol etabonate (LE) as an anti-inflammatory drug. As well, the water soluble antifungal fluconazole (FLZ) has been formulated into ophthalmic niosomal gels, microemulsions, in situ gels aiming to provide sustained release and prolonged residence time. characterization of these formulations regarding pH, viscosity, and drug content has been accomplished. In-vitro release characteristics and accelerated stability of the prepared formulae were a matter of interest in this investigation. Also, in-vivo study of some selected stable formulae has been performed to examine the ocular bioavailability of the investigated drugs. To fulfill these goals, this thesis comprised the following two parts : The first part deals with the development and evaluation of loteprednol etabonate ophthalmic preparations. The second part deals with the development and evaluation of fluconazole ophthalmic preparations. PART I : Development and evaluation of loteprednol etabonate ophthalmic preparations. This part deals with the investigation of release characteristics, accelerated stability, and ocular bioavailability of loteprednol etabonate from ophthalmic gels, drops, and ocuserts. Furthermore, the effect of the drug on the decongestion time of inflamed rabbits’ eyes was studied. This part includes three main chapters: Chapter I : Formulation and in-vitro evaluation of different ophthalmic preparations of loteprednol etabonate The work in this chapter involved the preparation of inclusion complexes of LE with each of hydroxypropyl-beta-cyclodextrin (HP-β-CyD) and beta-cyclodextrin (β-CyD) by three different methods including kneading (KN), co-precipitation (CO) and freeze drying (FD). Furthermore, the formulation of untreated LE or its complexes with each of HP-β-CyD and β-CyD into different ophthalmic gel, DROP and ocusert bases were investigated. Gel and DROP bases included hydroxylpropyl methylcellulose (HPMC), methylcellulose (MC) and sodium alginate (ALG). Ocusert bases were HPMC, MC, and ALG, each in combination with CP934. The characterizations of the prepared formulae were performed regarding drug content, pH, viscosity, and in-vitro release. Finally, the kinetic analysis of release data was done.