Powder like samples named MVPS, containing 95.8% of polysaccharide, were extracted from a well-known marine bivalve Mactra veneriformis. Some in vitro tests were carried out to characterize its physicochemical properties. X-ray diffraction and thermodynamics tests indicated that MVPS were noncrystalline but thermostable polymers. Solubility and rheology tests showed that MVPS could easily dissolve in aqueous media and its solution obviously belonged to non-Newtonian fluids even at relatively high concentration. Furthermore, via blending MVPS solution with other polymers and then spray drying the blends, several composite microparticles were prepared. The chitosan/MVPS particles are available not only with spherical morphology but also with higher production yield. As a model drug, metformin can be encapsulated into the composite microsphere and then achieve the sustained release. The chitosan/MVPS composite microspheres loaded with drug might be an appropriate for nasal formulation since its particle sizes are in the range of 1-10 mu m.

Microsphere formulation; Mactra veneriformis; Spray drying; Blending

Nanjing University of Chinese Medicine