Disodium norcantharidate loaded poly(ɛ-caprolactone) microspheres: I. Preparation and evaluation

Poly(ɛ-caprolactone) (PCL) microspheres encapsulating disodium norcantharidate (DSNC), a drug in salt form and with high water solubility, were prepared by s/o/w solvent evaporation technique and characterized in terms of size, morphology, encapsulation efficiency and drug release. The viscosity of s/o dispersion was crucial to the successful encapsulation of DSNC. Scanning electron microscopy (SEM) studies showed that the drug-loaded microspheres had coarse surface and porous internal structure. The analysis of X-ray diffraction (XRD) indicated that there was no interaction between DSNC and PCL, but the degree of crystallinity of PCL decreased with the introduction of the drug. The drug release profiles indicated an initial burst release followed by a slow release, and a further investigation into the release mechanism implied that the release of DSNC from PCL microspheres was caused by a combination of diffusion and osmotic pressure.