Study on preparation and in vitro release of norcantharidin-loaded chitosan microspheres

Objective:To study the preparation technique and in vitro release characteristics of norcanthari- din-loaded chitosan microspheres.Methods:Norcantharidin-loaded chitosan microspheres were achieved by emulsi- fication cross-linking process with liquid paraffin as oil phase,Span-80 as emulsifier,and formaldehyde as cross linking agent.The uniform experimental design was applied to optimize the formulation and preparation procedure. The surface morphology of the microspheres was observed by scanning electron microscope(SEM).Dynamic dialy- sis method was used to determine the release characteristic of norcantharidin from microspheres in vitro.Results: Novel microspheres with a global shape and narrow distribution were prepared.The average diameter was(25±10)μm.The drug-loading rate was(15.08±2.85)%.The entrapment rate of microspheres was(57.80±1.35)%.The drug release behavior in 0.1 mol·L~(-1)hydrochloride,phosphate buffered saline(pH 5.3)and physi- ological saline was discribed by Higuchi model.Conclusion:The optimized preparation technique was feasible,and microspheres with high drug-loading rate and evident effect of sustained drug release were prepared.