The objective of this study was to formulate controlled release pellets of cetrizine dihydrochloride and optimize the effect of formulation variables i.e. concentration of Eudragit RLPO and ethyl cellulose. The experimental design selected was 32 full factorial design using these two variables. Drug release after 24 hr and t50% were evaluated as response parameters. Polymers were coated onto the drug loaded pellets using pan coater. It was observed that the concentrations of polymers directly affected the drug release profile. Eudragit RLPO and ethyl cellulose showed effects opposite to each other on drug release. Mathematical models were generated for each response parameters to predict their values at selected levels of formulation variables. The effect of the variables and behavior of the system was studied using response surface plots. The optimized formulation showed drug release of 96.22% in 24 hr and t50% of 11hr 54 min. The results of this study revealed that the pellets of cetrizine dihydrochloride coated with 1:5 ratio of Eudragit RLPO: Ethyl cellulose showed optimum controlled release.
