Effect of Spray Drying Method on the Properties of Glimepiride-loaded Solid Dispersion

Abstract

Glimepiride (GLI) is a third-generation sulfonylurea class antidiabetic drug that has low aqueous solubility. The objective of this study was to evaluate the effect of solvents in the development of GLI-loaded solid dispersions (GLISD) using spray drying technique. Two GLI-SD were prepared by adding GLI, polyvinylpyrrolidone (PVP K30), and sodium lauryl sulfate (SLS) in an ethanol/water mixture (solvent evaporation, SE) and water only (surface attached, SA). Intrinsic saturated solubilities and in-vitro dissolution were evaluated and compared to the GLI powder and physical mixture (PM). In addition, physicochemical studies such as scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction were also evaluated. We found that the solubility of GLI was significantly improved by both the preparation methods. The SE method showed 4,960-fold improvement while the SA method displayed 2,900-fold enhancement, which is equivalent to the PM. The in-vitro dissolution studies showed that both methods had a higher release rate, about 1.3-fold for SE and 2-fold for SA, as compared to pure GLI powder. However, GLI release slightly decreased with time for the SA method. Furthermore, solid-state characterizations also revealed that most of the crystalline drug was transformed to the amorphous form in both GLI-SD. Thus, these results indicate that choice of the solvent system plays an important role in the spray drying technique which affects the solubility, dissolution, and crystallinity of poorly soluble drugs such as GLI.