Effects of microwave on drug release properties of matrices of pectin

The influence of microwave irradiation on the drug release properties of pectinate and pectinate-chitosonium beads was investigated. The beads were prepared with the highest possible concentration of polymer by an extrusion method. Sodium diclofenac was selected as a model water-soluble drug. The beads were subjected to microwave irradiation at 80 W for 5, 10, 21 and 40 min. The profiles of drug dissolution, drug content, drug stability, drug-polymer interaction and polymer-polymer interaction were determined by dissolution testing, drug content assay, differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The chemical stability of drug in beads was unaffected by the microwave irradiation. The drug release property of pectinate beads was mainly governed by the extent of polymer interaction in matrix. Treatment of pectinate beads by microwave led to an increase in the extent and rate of drug released owing to reduced pectin-pectin interaction via CO of COOH and/or COOCH3 of the polymer. The extent of drug released from the pectinate beads could not be reduced merely through the coacervation of pectinate matrix with chitosan. Treatment of pectinate-chitosonium beads by microwave was essential to reduce the rate and extent of drug released from the matrix, following an increase in drug-polymer and polymer-polymer interaction in beads. Treatment of chitosonium beads by microwave at 80 W for 5 min reduced the rate and extent of drug released from the matrix. Nonetheless, the degree of reduction in the extent of drug released from the chitosonium beads was lower than that of the pectinate-chitosonium matrix and the release of drug from the chitosonium samples was not markedly retarded through the treatment of beads by microwave for a period of duration longer than 5 min. The findings indicated that both pectin and chitosan were needed in the formulation of a controlled-release matrix using the microwave technology.