Physicochemical characterization of naproxen solid dispersions prepared via spray drying technology

The bioavailability of Naproxen (NPX), a non-steroidal anti-inflammatory drug, is limited after oral administration due to its low solubility in biological fluids. The aims of this study were preparation and characterization of NPX solid dispersions benefitting hydrophilic polymers. Solid dispersions of NPX were prepared at different drug to polymer ratios (1:0.5, 1:1 and 1:2) using crosspovidone and HPMC E4M by means of spray drying method. The dissolution rate of NPX from the solid dispersions, drug/polymer physical mixtures and pure drug was determined at two pH values of 3 and 7.4 simulating gastric and intestinal fluids using USP dissolution apparatus II. The physicochemical properties of the prepared solid dispersions were also characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and Fourier transform infrared spectroscopy (FT-IR). The dissolution rate of NPX was noticeably increased in the solid dispersions so that almost 90% of drug was released at 60 min while the corresponding value for the physical mixtures and pure drug was revealed to be around 40%. The dissolution rates of the formulations were dependent on the nature and ratio of drug to carriers as well as pH of the medium. DSC and X-ray diffraction displayed reduced drug crystallinity in the solid dispersions. Scanning electron microscopy revealed significant decreased particle size of the drug in the solid dispersions. FT-IR spectroscopy demonstrated no obvious interactions between the drug and polymers.