| This subject applied lecithin to pectin-based systems for colon-specific drug delivery, and studied on the performance of pectin modified by lecithin.The influence of these formulation parameters was investigated upon bead performance, and comparison of properties of lecithin/pectin beads loading different drugs was studied. The preliminary study of the interaction mechanism of lecithin, pectin and other components in the system was to reveal the role of lecithin in modified pectin-based drug delivery system, improve system performance, expand the scope of the system.The pectinate beads loading ketoprofen were prepared by dripping methodising pectin as a carrier.The better formulation of pectin gel beads was screened by changing pectin type, degree of esterification and crosslinking type; Choose lecithin to modify pectin,The influence of the influencethe of ratio of pectin to lecithin, cross-linking agent concentration, cross-linking solusion pH, the ratio of pectin to drug and diameter of needle was investigated upon bead shape, size, encapsulation efficiency, drug loading and drug release pattern. Comparison of properties of calcium-pectin systems and zinc-pectin systems, and comparison of properties of lecithin/pectin beads loading indomethacin, ketoprofen and curcumi respectively were studied;And the interaction mechanism of lecithin, pectin and other components in the system was investigated by UV, surface tension, IR, DSC and other methods.Lecithin/pectin beads loading ketoprofen could be prepared by dripping method using ketoprofen as the model drug, lecithin as the modifier, metal ions as cross-linkings agent.In calcium-pectin systems, Lecithin was added to significantly improve the encapsulation efficiency of ketoprofen,but the sustained-release performance of calcium-pectin gel beads was not significantly improved,drug released completely in simulated gastrointestinal fluid at 7h.In zinc-pectin systems,lecithin, cross-linking agent concentration,cross-linking solusion pH, the ratio of pectin to drug and diameter of needle had a significant impact on bead shape, drug loading, encapsulation efficiency and release properties.Lecithin significantly improved the sustained-release performance of zinc-pectin gel beads loading ketoprofen.The drug release rate of lecithin/zinc-pectin beads obtained with 4% of pectin solution,Pectin:PC=4:2,Pectin:KTP=4:2,4% of ZnCl2 solution at pH 1.5 was only 2.8% at 5h in simulated gastro-intestinal conditions and 50.2% in simulated colonic medium with enzymes at 26h after reaching the colon,demonstrating colon-specific drug release.The size and shape of pectin beads loading different model drugs were similar.The influence of the different model drugs on drug loading, encapsulation efficiency and release properties of the gel beads was not the same.For the system loading indomethacin, ketoprofen and curcumi respectively, lecithin improved encapsulation efficiency of the three drug significantly. In vitro drug release study, it was significant that lecithin/calcium-pectin beads decreased the drug release rate for the system loading indomethacin in simulated gastro-intestinal conditions, but it was not obvious for the system loading ketoprofen and curcumin. It was significant that lecithin/zinc-pectin beads decreased the drug release rate for the system loading indomethacin ketoprofen and curcumin in simulated gastro-intestinal conditions.Lecithin is a surface active agent, a surface tension of pectin solution modified by lecithin decreased. Infrared spectra showed that displacement and disappearance of characteristic peaks of ketoprofen in lecithin/pectin gel beads did not happen, and the DSC spectrums of calcium-pectin beads and lecithin/calcium-pectin beads loading ketoprofen still both appeared ketoprofen endothermic peak, indicating that a part of ketoprofen interacted with other components, but a part of original ketoprofen was still in pectin gel beads.Lecithin can interact with pectin forming complex which can change drug release rate. However, the influence of lecithin on systems loading different drugs is different. It is significant that lecithin/calcium-pectin beads improve the drug release properties of the system loading indomethacin, but it is not obvious for the system loading ketoprofen and curcumin.It was significant that lecithin/zinc-pectin beads decreased the drug release rate for the system loading indomethacin ketoprofen and curcumin in simulated gastro-intestinal conditions. Lecithin demonstrates greater influence on the drug release properties of zinc-pectin formulation than calcium-pectin formulation. |
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