Fabrication, characterization and long-term in vitro release of hydrophilic drug using PHBV/HA composite microspheres

In this paper, we fabricated polyhydroxybutyrate-co-hydroxyvalerate (PHBV)/Hydroxyapatite (HA) composite microspheres as a long-term drug delivery system. The characterization and in vitro release properties of the system were investigated. It was observed that the PHBV/HA composite microspheres showed very low initial burst that could be neglected, owing to the high affinity and absorbability of nano-HA particles, and the sustained release lasted more than 10 weeks. The in vitro release rate was controlled by diffusion rate of drugs from polymer matrices, and the release profile can be expressed by the Higuchi equation. From our work, it indicated that PHBV/HA composite microsphere could be a promising long-term drug release system.