Preparation of polylactide-co-glycolide and chitosan hybrid microcapsules of amifostine using coaxial ultrasonic atomizer with solvent evaporation.

The objective of this study was to evaluate the effect of various processing and formulation factors on the characteristics of amifostine hybrid microcapsules. Amifostine-loaded hybrid microcapsules were prepared using PLGA and chitosan. In short, amifostine powder was dissolved in de-aerated water with or without chitosan. The amifostine solution was later emulsified into PLGA solution in dichloromethane containing phosphatidylcholine. The resultant emulsion was fed through the inner capillary of a coaxial ultrasonic atomizer. The liquid fed through the coaxial outer capillary was either water or chitosan solution. The atomized droplets were collected into PVA solution and the droplets formed microcapsules immediately. The hybrid microcapsules prepared with chitosan solution only as an outer layer liquid showed the maximum efficiency of encapsulation (30%). The median sizes of all three formulations were 33-44 microm. These formulations with chitosan showed positive zeta-potential and sustained drug release with 13-45% amifostine released in 24 h. When chitosan was incorporated into inner as well as outer liquid layers, the drug release increased significantly, 45% (compared with other formulations) released in 24 h and almost 100% released in 11 days. Hybrid microcapsules of amifostine showed moderately high efficiency of encapsulation. The cationic charge (due to the presence of chitosan) of these particles is expected to favour oral absorption and thus overall bioavailability of orally administered amifostine.