The Investigation Of Aminophylline Sustained-release Pellets Made By Fluidized-bed

Film coating technique carried on by a fluidized bed spray coater is always used for preparing sustained-release pellets, which is more simple technology, less equipment need, less costs and more output capacity. Besides, the apparent fluidity of products made by fluidized bed is well, and there is no dust and mass during production. In this dissertation, aminophylline which is used for treating asthma, has been made in to sustained-release pellets. And the study was aiming at validation in vivo, consisting of preparation methods for pellets, the sustained- release system of coated pellets, pharmacokinetics. Results showed: the sustained-release pellets had good appearance and the drug was released in vivo over 12h.The drug-excipient compatibility was studied between aminophylline and self-made blank pellets, using the pellets on market as the reference. Differential scanning calorimetry (DSC) was used as a screening technique besides with FT-IR spectroscopy and X-ray powder diffractometry. Aminophylline was found to be compatibility with self-made blank pellets but pellets on market. The studies of release seemed to sustain the result.UV spectrophotometry was developed for in vitro assay during the studies of release , and the plasma concentration in rabbits was monitored by using the HPLC ultraviolet method.Blank pellets were layered by exipients in liquid phase which was also used for drug carrying. The effects of process variables were investigated. Finally the content of the drug in the pellets is 36%.Ethyl Cellulose was used for pellets coating. The effects of process variables and formulation variables on coating pellets preparation were investigated. And The results showed: the coated pellets had a marked sustained release property. The description of release profiles suggested that among the different kinetics, the first-order became the most appropriate model to describe release kinetics.Using the aminophylline pills on market as the reference, the pharmacokinetics in rabbits of self-made sustained-release pellets were studied. The result indicated that Tmax was longer, whereas Cmax was lower than the pills on market. Furthermore, the results showed that the sustained release preparation had satisfactory sustained release effects and there was good correlation between absorption percent in vivo and accumulative release in vitro. And the aminophylline sustained release pellets show a good bioavailability.