Preparation and Evaluation of Hpmc-alginate Mucoadhesive Microcapsules of Diclofenac for Controlled Release

A new, novel promising technology for obtaining controlled release and enhancing the bioavailability is a combination of mucoadhesion principle and microencapsulation to result in mucoadhesive microcapsules. Mucoadhesive microcapsules consist of either entirely of a mucoadhesive polymer or having an outer coating enclosing the drug particles. They facilitate an intimate and prolonged contact with the absorption surface to provide controlled release and enhanced bioavailability of the contained drug over longer period of time to prolong its therapeutic action. The objective of the present work is to prepare HPMC based mucoadhesive microcapsules of diclofenac and to evaluate the microcapsules for mucoadhesiveness and controlled drug release characteristics. Spherical HPMC-alginate mucoadhesive microcapsules of diclofenac could be prepared by the orifice – ionic gelation method. Microencapsulation efficiency was in the range 98.7 % 103.5 %. Drug release from the HPMC – alginate microcapsules was slow and spread over a period of 12 h and depended on core: coat ratio and wall thickness of the microcapsules. Drug release mechanism from these microcapsules was by nonFickian diffusion. Good linear relationships were observed between wall thickness of the microcapsules and release rate [K0 and K1] of the microcapsules. Mucoadhesion testing by in vitro wash-off test indicated good mucoadhesive property of HPMC-alginate microcapsules with a slower washoff when compared to non-mucoadhesive EVA microcapsules. Thus controlled release mucoadhesive microcapsules of diclofenac could be designed employing HPMC-alginate. HPMC-alginate microcapsules of diclofenac exhibited good mucoadhesion and controlled release characteristics and were found suitable for oral controlled release of diclofenac. INTRODUCTION: In recent years, increasing attention has been focused on the manner in which the drugs are delivered. Drugs are being incorporated into polymeric systems and devices for controlled and targeted drug release. The goal of any drug delivery system is to provide a therapeutic amount of drug to the proper site in the body to achieve the desired drug concentration and then maintain it. The delivery system should fulfill spatial placement and temporal delivery of the drug. The controlled release drug delivery systems are aimed at controlling the rate of drug delivery, sustaining the duration of therapeutic activity and/or targeting the delivery of the drug to tissue. Drug release from these systems should be at a desired rate predictable and reproducible.