Properties of solid dispersion of piroxicam in Pluronic F-98

Abstract

A solid dispersion approach (SD) has been developed to enhance the dissolution properties of insoluble drugs by improving their aqueous solubility. An insoluble drug, piroxicam (PXM), was dispersed in a water-soluble carrier, Pluronic F-98 (Pl. F-98). Different methods were employed to prepare such dispersion, namely: the solvent method (SM), the melting method (MM), the melting-solvent method (MSM), the co- grinding method (GM) and the kneading method (KM). Solid dispersion obtained using the solvent method was prepared using different solvents, namely: methylene chloride, acetone and chloroform. Different tools were used, to characterize the prepared solid dispersion, such as the infrared spectroscopy (IR), the powder X-ray diffractometry (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The dissolution rate from the prepared SDs was determined in simulated gastric fluid and was found in the following order: KM > MM > GM > PM (physical mixture) > SM > MSM > PXM. Solubility of the free and of the dispersed drug was determined at different temperatures and solution heats were calculated. The results revealed that solubility of the dispersed drug was markedly enhanced by the rise in temperature. From this study, the increased dissolution rate in systems containing Pl. F-98 was probably the result of increased wettability and dispersibility, as well as particle size reduction of PXM and decrease in the crystalline fraction of the drug, since no interaction could be demonstrated between PXM and Pl. F-98.