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. Svrha istraživanja bila je poboljšati udio vodotopljive ljekovite tvari metronidazola u pripravcima s pektinskim zrncima koristeći sredstva za umrežavnje poput kalcijevog karbonata. Površinski umrežena zrnca kalcijevog pektinata s metronidazolom pripravljena su dokapavanjem otopine lijeka i pektina u 1 i 5% (m/V) otopinu kalcijevog klorida. Zrnca s umreženom jezgrom pripravljena su dispergiranjem kalcijevog karbonata u otopinu ljekovite tvari i pektina. Zrncima su određeni sljedeći parametri: veličina čestica, sposobnost bubrenja, SEM, DSC i oslobađanje ljekovite tvari in vitro. Zrnca dobivena umrežavanjem jezgre sadržavala su veći udio lijeka (10--20%) od površinski umreženih zrnaca. Zrnca dobivena s 1% (m/V) otopinom kalcijevog klorida sadržavala su veći udio lijeka od onih dobivenih s 5% otopinom. Kapacitet vezanja vode zrnaca ovisio je o jakosti gela, a jakost gela ovisila je internom agensu za geliranje i koncentraciji pektina. U kiselom mediju ljekovita tvar se u potpunosti oslobodila unutar 30--60 minuta.