Abstract: The aim of this study was to prepare sodium alginate coated liposome containing calcitonin and to study its mucoadhesive properties in vitro and in vivo.The positive charged liposome containing calcitonin was prepared through thin film hydration with the entrapment efficiency of (86.2±2.3)%.The non-coated liposome was coated with sodium alginate solution with various viscosity to get the sodium alginate coated liposome and the Zeta potential of sodium alginate coated liposome switched to negative charge.The in vitro and in vivo mucoadhesive properties were evaluated by ss-mucin particle method,tissue homogenation and confocal laser scanning microscopy.It was shown that sodium alginate attached to the mucin particles changed the Zeta potential of them.Furthermore,the quantity of the fluorescent material in rat intestinal tissue increased when the liposome was coated with sodium alginate.With the increase of the viscosity of sodium alginate,the higher quantity of the fluorescent material was observed.The images of confocal laser scanning microscopy also showed that the sodium alginate coated liposome showed stronger intensity of fluorescence than non-coated liposome.In conclusion,sodium alginate coated liposome had better mucoadhesion than non-coated liposome and the viscosity of sodium alginate could increase the mucoadhesion.