Studies on Solubility Enhancement of Poorly Soluble NSAID Using Dual Approach of Micro-environmental pH Modulation and Melt Granulation

Background: The present work describes the role of melt granulation and microenviron-mental pH modulation technique in solubility enhancement of a poorly water soluble NSAID, Aceclofenac (ACL). ACL is a BCS Class II drug showing dissolution rate limited absorption and pH dependent solubility, with higher solubility at alkaline pH. The limited solubility of ACL affects drug absorption and hence, therapeutic effect as the drug is indicated in conditions of pain where rapid onset of action is desired. Methods: Solubility enhancement of ACL was carried out by melt granulation technique using Gelucire 50/13 as molten carrier. The solubility of ACL was improved further by incorporating sodium hydrogen carbonate as pH modifier. The granules of ACL thus developed, were compressed into tablets using adsorbing carriers and other tableting excipients. Results: This dual approach not only enhanced ACL solubility but also aided in achieving a pH independent release. The developed tablets exhibited pH independent release as well as enhanced rate of dissolution which is indicated by in vitro dissolution studies and ex-vivo intestinal permeation studies. The pH independent release would ensure absorption of drug throughout the gastrointestinal tract. The solubility enhancement of ACL was further confirmed by characterization studies such as DSC and XRD. Conclusion: Thus, the dual approach of melt granulation and micro-environmental pH modulation can be simple and scalable method for solubility enhancement of poorly soluble drugs showing pH dependent dissolution rate limited absorption.