Effects of Blending a Nonionic and an Anionic Cellulose Ether Polymer on Drug Release from Hydrophilic Matrix Capsules

Blends of hydroxyethylcellulose (HEC) and sodium carboxymethylcellulose (NaCMC) were used to achieve zero order release of chlorpheniramine maleate (CM) from hydrophilic matrix capsules. Dynamic swelling/erosion 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 influence water uptake and erosion of the matrix mixture. The factors by which zero-order drug release is achieved may include synchronization of the rates of water uptake and polymer erosion even though a constant diffusional pathlength may not be maintained. The combined mixture factorial design presented in this study allows for the characterization and optimization of the drug release profiles.