SURFACTANT EFFECTS ON ALGINATE MICROSPHERES

In the production of calcium alginate microspheres invoking an emulsif ication process, the surfactants incorporated can affect the formation of the microspheres. In this study, the influence of the blend of sur factants, hydrophile-lipophile balance (HLB) and the sequence of addit ion of surfactant on the properties of the microspheres was determined . The findings showed that maintaining the same HLB, surfactants with more fatty acid chains produced larger microspheres which also have hi gher drug content, whereas for surfactants with longer polyoxyethylene chains, the microspheres were smaller. Varying the HLB, whilst keepin g the same blend of surfactants, resulted in changes in the size and s hape of the microspheres. The incorporation of the hydrophilic surfact ant into the aqueous phase containing the drug gave rise to larger mic rospheres. These had a lower drug encapsulation efficiency. The drug r elease rate was faster, and this is attributed to the presence of unen capsulated drug crystals in the product.