Physicochemical characterization and drug release studies of naproxen solid dispersions using lactose as a carrier

Naproxen solid dispersions were prepared by melting and rapid cooling with liquid nitrogen using lactose as a carrier. The physical characteristics of these solid dispersions were investigated by powder X-ray diffraction, differential scanning calorimetry and dissolution rate analyses. The degree of crystallinity of naproxen in solid dispersions decreased with decreases in the molar ratio of naproxen to lactose. Fourier-transform infrared (FT-IR) analysis demonstrated the presence of intermolecular hydrogen bonds between naproxen and lactose in solid dispersions. Dissolution studies indicated that the dissolution rate was markedly increased in solid dispersions compared with physical mixtures and pure drugs. These results indicated that lactose is useful as a carrier for production of solid dispersions.