Ocular Mucoadhesive and Biodegradable Sponge-Like Inserts for the Sustained and Controlled Delivery of Voriconazole; Preparation, D-optimal Factorial Optimization and in-vivo Evaluation

Abstract

The aim of this study was to formulate and optimize by statistical means mucoadhesive and biodegradable sponge-like inserts loaded with voriconazole (VCZ) which increases the contact time of the drug with the eye and sustain its release from the formula in a controlled manner. This avoids the pulsed effect reported for the drug suspension and results in reducing the number of drug instillations in the eye with the result of enhancing the patient compliance. Also, the sponge like nature of the insert reduces the foreign body sensation caused by other ocular solid dosage forms. They were prepared using casting/freeze-drying technique using five polymers namely high molecular weight chitosan (CH), sodium alginate (AL), sodium carboxy methyl cellulose (CMC), gellan gum (GG) and xanthan gum (XG). The prepared inserts were subjected to evaluations of their visual appearance, weight variation, drug content, surface pH, in-vitro release (percent drug released after 1h (Q1 (%)), mean dissolution time (MDT) and dissolution efficiency (DE)) in addition to kinetic analysis of the release data, water uptake, mucoadhesion and rheology of the forming plain polymer solution at the maximum rate of shear. The independent variables of the D-optimal factorial design were the polymer type and concentration while Q1 (%), MDT, DE, % water uptake after 15 minutes and rheology at the maximum rate of shear were chosen as dependant variables. The performed optimization process using design expert software showed an optimum formula consisting of 2 % GG. It showed slow release behavior compared to the drug suspension. FTIR and DSC studies showed that there is no interaction between VCZ and GG. The optimum formula has good in-vitro mucoadhesive properties and pH in the safe ocular range. Moreover, it showed promising in-vivo results of rapid hydration and gelling in addition to good mucoadhesive behavior when instilled in the eye, high ocular safety and biocompatibility, sustained antifungal activity in comparison to the drug suspension and finally biodegradation. So, it may be taken into consideration as an outstanding carrier for the ocular delivery of VCZ.