EVALUATION OF IN VIVOE-IN VITRO RELEASE OF THEOPHYLLINE FROM NOVEL CONTROLLED RELEASE MICROSPHERES

摘要

Objective: The study is focused on the development of a new particulate drug delivery system using a modified chitosan matrix containing theophylline as a model drug molecule for drug prolonged release. Methods: The polymeric beads of HKCTS-Zn loading theophylline are first prepared by zinc cross-linked. Modifications in matrix structure and physicochemical behaviour caused by the cross-linking reaction were assessed during particle formation and drug release. The correlation between the dissolution in vitro and the absorption in vivo of the sustained-release theophylline beads were then investigated. Rotating basket method was used to determine in vitro release rate. The drug plasma was determined by HPLC after a single oral dose of 50mg sustained beads was given to guinea pigs. The in vivo absorption percentage was calculated by Wagner-Nelson equation. Results: The data showed that the drug dissolution coincided with Higuchi equation. The good linear regressive equation established between the absorption percentage in vivo and the dissolution percentage in vitro of the sustained-release theophylline beads. Conclusions: The generated beads proved to be successful in prolonging drug release. The dissolution in vitro of the sustained-release theophylline beads in the stimulated gastric fluid proves to be related to in vivo absorption percentage