Influence of solvent mixtures on HPMCAS-celecoxib microparticles prepared by electrospraying

Hypromellose acetate succinate (HPMCAS) microparticles containing the poorly-water soluble drug celecoxib (CEL) were prepared by electrospraying intended for oral drug delivery. Various solvent mixtures with different solubility for CEL and HPMCAS were used to induce changes in the polymer structural conformation of the microparticles. The performance of the prepared microparticles was evaluated by studying the solid state from, particle size and morphology, radial drug distribution and drug release. CEL was amorphous in all electrosprayed HPMCAS microparticles. The particle size and morphology was dependent on the solubility of HPMCAS in the solvent mixture used with poorer solvents resulting in smaller microparticles with rougher appearance. The CEL distribution on the particles surface was relatively homogeneous and similar for all microparticles. Drug release from the microparticles was observed at a higher rate depending on the solubility of HPMCAS in the solvent used for electrospraying, and in all cases an at least 4-fold higher rate was observed compared with the crystalline drug. Drug precipitation from the supersaturated solution was inhibited by HPMCAS for all microparticles based on its parachute effect while crystalline CEL did not reach supersaturation. This study demonstrated that electrospraying can be used to produce microparticles with tailored properties for pharmaceutical application by adjusting solvent selection.