This book addresses the formulation and process design aspects of extended release micro particles of BCS class IV drug Rifaximin through cyclodextrin complexation and extending the drug release by Eudragit L -100 enteric coating. The concept of surface response methodology was used in the selection of optimized batch that was further evaluated for various parameters. The data supports an improvement in aqueous solubility of BCS class IV drugs through cyclodextrin complexes. The release of such inclusion complexes can be retarded for 8 hrs by enteric coating.