Investigation of cellulose ether polymers in controlled drug delivery
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Cellulose ethers are widely used in a variety of pharmaceutical applications. The purpose of this research was to investigate the use of cellulose ether polymers to formulate different oral pharmaceutical dosage forms, and to control the release of active ingredient from the specific drug delivery system over an extended period of time. In this study, applications of the cellulose ether polymer in matrix tablets and multiparticulate dosage forms, were investigated. Specifically, ethylcellulose (EC) used in aqueous polymeric coating, and hydroxypropyl methylcellulose (HPMC) used in hydrophilic matrix tablets, were investigated in this study. Formulations and processing parameters were developed and optimized in order to achieve the desirable rate of drug release from each drug delivery system. For the matrix tablet system, an efficient method to achieve complete recovery of alprazolam from powder blends and tablets containing HPMC was developed and qualified. Formulation parameters, including tablet size, polymer levels, excipient type and level, molecular weight type of HPMC, and dissolution media, were investigated and optimized during development of the drug delivery systems. Finally, two oral controlled release tablet formulations (containing different molecular weight types of HPMC) with equivalent dissolution profiles were developed and used for in vivo bioequivalence study. Molecular weight types of HPMC did not influence in vitro or in vivo performance of controlled release tablets and provided bioequivalent results in both fed and fasted states. For the multiparticulate system, the amount of drug release from EC coated matrix beads was influenced by drug type, plasticization, water-soluble additive, and curing condition. Optimum curing conditions were determined in order to ensure complete film coalescence without disrupting film integrity. Additionally, the amount of theophylline released from EC coated beads was manipulated by the inclusion of different types and levels of water-soluble additives. As found for both controlled release drug delivery systems, formulation and processing parameters must be investigated and optimized in order to achieve desirable release profiles and stabilize the amount of drug released throughout the shelf-life of the product.