Controlled Release of Nifedipine from Microspheres Spray Dried with Eudragit and Polyvinylpyrrolidone

抄録

Microspheres of nifedipine (NP) with combined carriers, Eudragit RS 100 (ERS) and polyvinylpyrrolidone K30 (PVP), at different NP-ERS-PVP mixing ratios of 1:10:0, 1:8:2, 1:5:5, 1:2:8 and 1:0:10 were prepared by a spray-drying technique. The effects of PVP content, inlet temperature and spray concentration on the physicochemical properties of microspheres and NP release characteristics were investigated. From X-ray diffraction patterns, microspheres showed the existence of NP in an amorphous state regardless of their compositions. Differential scanning calorimetric thermograms showed that the endothermic peak due the fusion of NP disappeared in all microspheres. The dissolution efficiency of NP from the microspheres depended mainly on PVP content. The drug release of microspheres containing a high PVP content followed the Higuchi diffusion-controlled mechanism whereas those with a high ERS content demonstrated zero-order release. The release rate constants with higher PVP content were higher than those with higher ERS content. Controlled release could be achieved by using the appropriate contents of ERS and PVP and the spray-drying technique.