Drug release properties of pectinate microspheres prepared by emulsification method

This study explored the potential of pectin for use in making microspheres for sustained-release of drugs. The pectin microspheres were prepared by external gelation using an emulsification technique with calcium chloride as the crosslinking agent. The influences of drug core (sulphanilamide, sulphaguanidine and sulphathiazole) and dissolution media (distilled water, USP HCl and phosphate buffers) on the drug release properties of the pectinate microspheres were examined. The morphology and drug content of the microspheres, and the solubility and solution pH of the drugs were also determined. Pectinate microspheres were successfully prepared by the emulsification technique. The rate of drug released from microspheres was highest in USP HCl buffer, followed by USP phosphate buffer and distilled water. Interestingly, the lowest percentage of drug released was produced by microspheres which were smallest in size and therefore largest in specific surface area, and consisting of sulphanilamide, the most water soluble drug. Further investigation showed that the microspheres consisted of both bound and unbound drugs. The percentage of drug released was predominantly determined by the relative contents of bound and unbound drugs embedded in the pectinate matrix.