EFFECTS OF BLENDING A NONIONIC AND AN ANIONIC CELLULOSE ETHER POLYMERON DRUG-RELEASE FROM HYDROPHILIC MATRIX CAPSULES

Blends of hydroxyethylcellulose (HEC) and sodium carboxymethylcellulos e (NaCMC) were used to achieve zero order release of chlorpheniramine maleate (CM) from hydrophilic matrix capsules. Dynamic swelling / eros ion and response surface measurements were made to provide an insight into the drug release behavior. The drug to total polymer and the HEC to NaCMC ratio influences the rate of drug release. NaCMC appears to i nfluence water uptake and erosion of the matrix mixture. The factors b y which zero-order drug release is achieved may include synchronizatio n of the rates of water uptake and polymer erosion even though a const ant diffusional. pathlength may not be maintained. The combined mixtur e factorial design presented in this study allows for the characteriza tion and optimization of the drug release profiles.