طراحی میکروپارتیکل های وابسته به pH پیروکسیکام و بررسی خصوصیات انحلال آنها

Abstract

The purpose of this study is preparation and evaluation of enteric release piroxicam microparticles in presence of Eudragit S100 to improve the dissolution rate and reduce the local gastrointestinal irritation of water-insoluble drug; piroxicam by combining the preparation of microspheres and the solid dispersion in one step. Microparticles were prepared by quasi-emulsion solvent diffusion method with different ratios of drug, Eudragit S100 as an enteric polymer, Aerosil as an antiadhesion agent and Hydroxypropyl methylcelloluse (HPMC) as a hydrophilic polymer. The micromeritic properties such as particle size, shape and flowability were investigated and invitro release characteristics of microparticles were evaluated.The physical state of piroxicam in microparticles was analysed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometry. The stability of microspheres was also evaluated in a 3-month accelerating condition stability. The results showed that spherical and uniform microparticles were obtained with high encapsulation efficiency (>90%) and improved micromeritic properties. The physical state investigations indicated that crystalline form of piroxicam in microparticles was disordered, suggesting that piroxicam was highly dispersed in microparticles as amorphous state. Also microparticles were stable after 3 mounth storage in accelerating conditions . Drug release studies showed that piroxicam in microparticles was well protected in an acidic medium and increased dissolution rate in basic medium from the polymeric solid molecular dispersion as compared with the crystalline pure drug. In addition, incorporation of HPMC as a hydrophilic polymer within the microparticles, elevated piroxicam release rate. Thus, present study demonstrated the high potential of spherical crystallization technique for obtaining stable microparticles of poorly water soluble drugs using enteric polymers carriers.