Study On5-aminosalicylic Colon-specific Sustained-release Pellets

Objective:To prepare a colon-specific delivery system for pH and time controlled sustained-release pellets of5-aminosalicylic (5-ASA) and investigate its stability.Methods:Ultraviolet spetrophotometry method was established for drug release of5-ASA. High performance liquid chromatography method was established to determine content and related compounds of5-ASA.5-ASA pellets were prepared by extrusion-spheronisation. The formulation and technology of5-ASA pellets were optimized with orthogonal experiment design. Aqueous dispersion (Eudragit NE30D) was used as sustained coating material and coating process was performed on a mini-fluid bed spray coater. The effects of process variables and formulation variables on pellets preparation were investigated. The formulation and technology of5-ASA sustained-release pellets were optimized. Eudragit S100was used as out layer for pH control and triethyl citrate added to the dispersion as the plasticizer. The formulation and technology of5-ASA colon-specific sustained-release pellets were optimized. In vitro the release rates of the5-ASA pellets were investigated to evaluate the factors which influence the release behaviors of the pellets. The fit factors method was used to study the stability of the5-ASA colon-specific sustained-release capsule.Results:The UV and HPLC methods were monitored by methodology and were accurate and stable. The pellets had good appearances and high yield. The Eudragit NE30D coated pellets had a marked sustained-release property, the drug release profile in vitro followed first order kinetics. The Eudragit S100coated pellets were not release in the simulated stomach and small intestine juice. The data of release in vitro showed that it met the requirement of the colon-specific pellets. The content, related compounds and release stability of the capsule were good under high temperature, high humidity and intensive light tests.Conclusion:The UV and HPLC methods were simple and accurate to be used in vitro. The pellets made by extrusion-spheronisation had good appearances and high yield. The pH and time controlled sustained-release pellets for5-ASA colon-specific delivery can be prepared by regulating the thickness of the outer and inner coating layers. The capsule was stable under high temperature, high humidity and intensive light tests.