Feeding liquid, non-ionic surfactant and cyclodextrin affect the properties of insulin-loaded XXXX microspheres prepared by spray-drying.

@entity6496 @entity7050 @entity10124 @entity291 @entity1543 @entity12185
The potential of spray-drying technique for the encapsulation in @entity10124 ( @entity7050 ) microspheres of @entity291 insulin, a poorly stable peptide, has been investigated. Insulin-loaded microspheres were prepared by spray-drying different feeding liquids containing insulin and @entity7050 , that is a S/O dispersion, a W/O emulsion or an @entity1543 solution. In the case of the emulsion, insulin was also co-encapsulated with either non-ionic surfactants such as @entity6496 20 and @entity12185 , or complexing agents such as HPbetaCD. In the microspheres prepared from the @entity1543 solution of insulin and @entity7050 , HPbetaCD was tested. Microspheres containing surfactants were aggregated, whereas good quality particles displaying a mean diameter in the range 12.1-27.9 microm were produced in the other cases. Insulin was efficiently loaded inside microspheres except for S/O formulation (only 22% of total insulin content was entrapped). The impact of the microencapsulation process on insulin chemical and conformational stability was assessed by HPLC, circular dichroism and turbidimetry studies. Under the adopted manufacture conditions, insulin was encapsulated in the native state and its chemical and conformational stability was preserved along the fabrication process. The formulations containing only insulin displayed low burst effects (6-11%), whereas the addition of surfactants resulted in much higher burst effects (49-54%) and faster release rate. The co-encapsulation of HPbetaCD slowed down the overall release rate and, in the case of microspheres prepared from the emulsion, allowed a constant insulin release up to 45 days. The study of insulin stability along the release phase showed that insulin was released in the intact form and un-released insulin was stable inside all the microsphere formulations. We conclude that insulin can be effectively encapsulated in @entity7050 microspheres by the spray-drying technique. Additives with complexing properties such as HPbetaCD have demonstrated a potential in optimizing the release rate of insulin when used in microspheres prepared from W/O emulsions.
