The Factors Influence The Burst Effect Of Irinotecan Microspheres And The Methods To Control This Effect

Microspheres have been used widely in drug delivery applications. The majority of the particles are prepared by the conventional emulsion methods, which tend to result in particles with heterogeneous size distribution with sub-optimal drug loading and release properties. The aim of this study is to prepare Irinotecan microspheres with different characteristics. In vitro release test were carried out, aiming to examine the influence of various factors such as process, prescription and release medium on the burst release of Irinotecan microspheres. Different batches of Irinotecan-PLGA microspheres were prepared by emulsification- solvent evaporation method. The parameters and prescription were changed in the process. Cylindrical particles and truncated cone particles were prepared by the hydrogel template method using gelatin as soft template. The results showed that, the particles with cumulative release rate within the 24 hours from high to low were spherical>cylindrical 1(flat) > cylindrical 2(high) > truncated cone. Irinotecan- zein microsphere was prepared by phase separation method, and their initial burst release was larger than that of Irinotecan-PLGA microspheres. Irinotecan- chitosan microspheres were prepared by emulsion crosslinking method, and the microspheres were released slowly and the cumulative release rate was too low. Technological parameters which can reduce the burst release effect were finally determined according to the release results, and the release curves were drawn. The results showed that when the oil-water ratio was 1:5, material ratio was 1:10, the oil phase concentration was 25%, and the aqueous phase concentration was 2%, the release curve of the microspheres prepared was smooth, and the cumulative release rate in 24 hours was relatively small, yet the initial burst release was minimal.