Encapsulated hydrophilic polymer beads containing indomethacin as controlled release drug delivery systems

Encapsulated hydrophilic polymer beads containing indomethacin were prepared by a combined technique of bead polymerization and phase separation. The drug delivery system consisted of the copolymer of 2-hydroxyethyl methacrylate and acrylamide as the core matrix and ethyl cellulose as the barrier membrane. The drug was incorporated into the polymer matrix during the formation of the beads. The system was found to be useful as a sustained release dosage form. Release of drug from the coated beads followed a zero-order rate up to 40% of the drug released. A linear relationship exists between the rate of release and the reciprocal amount of ethyl cellulose used for coating, indicating that the drug release was controlled by the coating thickness. Addition of polyvinyl pyrrolidone in the formulation significantly increased the amount of drug released. Blood level studies showed that drug absorption from the encapsulated beads was lower than that of indomethacin powder. It appeared that indomethacin was completely absorbed from the encapsulated beads.