摘要：The purpose of this study was to improve the entrapment efficiency of the water-soluble drug metronidazole using internal cross-linking agents.Calcium pectinate beads containing metronidazole were prepared by dropping a drug-pectin solution in 1% and 5% (m/V) calcium chloride for surface cross-linked beads.For the core cross-linked beads calcium carbonate was dispersed in the drug-pectin solution.The beads were characterized by particle size,swelling ratio,SEM,DSC,and in vitro drug release.It was found that the beads obtained by core cross-linking produced more drug entrapped beads than the surface cross-linked beads.Beads obtained using 1% (m/V) calcium chloride showed more drug entrapment than these obtained using 5% calcium chloride.The core cross-linking of pectin beads reduced drug loss by about 10–20%.The water lodging capacity of beads depended upon gel strength which is a function of the internal gelling agent and pectin concentration.Complete drug release was observed within 30–60 min in the acidic dissolution medium.This work has showed that the core cross-linking agent increases the water-soluble drug entrapment in calcium pectinate beads.
