PREPARATION OF POLY(3-HYDROXYBUTYRATE) MICROSPHERES CONTAINING LASTET OF AN ANTICANCER DRUG AND ITS APPLICATION TO DRUG DELIVERY SYSTEM

Poly(3-hydroxybutyrate) (PHB) microspheres containing lastet (5 approximately 10 wt%) of an anticancer drug were prepared by a solvent-evaporation process. Average diameters of PHB microspheres were regulated in the range 20 approximately 150-mu-m by varying the concentration of PHB in methylene chloride from 6.5 to 29.6 g/l. The release profiles of the drug from the microspheres were studied in vitro in a 0.01 M phosphate buffer (pH 7.4) at 37-degrees-C. The release rate of the drug was very small and only 25% of the loaded drug was released for 20 days. The drug release from PHB microspheres was markedly accelated, when glycerol tristearate (GTS) was mixed with PHB. The release rate of the drug increased with the GTS content in PHB microspheres and all of the loaded drug was released within 10 days. The release rate of the drug decreased with an increase in the average diameter of PHB microspheres.