Preparation and Evaluation of Andrographolide Solid Dispersion Vectored by Silicon Dioxide

Background: Andrographolide (Andro) is a “natural antibiotic” as well as a typical insoluble drug. The purpose of this study was to investigate the feasibility of commercially available silica (SiO2) as a carrier of solid dispersion to enhance the dissolution of Andro. Materials and Methods: The solvent evaporation method was adopted, and a series of process parameters were studied to prepare a solid dispersion. Andro, SiO2, physical mixture, and solid dispersion were characterized with respect to particle size distribution, special surface area, pore volume, and scanning electron microscopy, Fourier transform infrared spectroscopy, and X‑ray diffraction studies. Results: Single factor test suggested the best preparation of solid dispersion was the drug and carrier (SiO2B) ratio of 1:8, with tetrahydrofuran as the solvent, and a recovery temperature of 50°C. Compared to crude drug and mixture, solid dispersion was found to form a unique structure to disperse the drug and displayed superior performance in rapid dissolution. Conclusion: The present study signifies the commercially available SiO2 is an excellent but cheap carrier to improve the dissolution of Andro. Our results provide a highly operability approach for improving the dissolution of insoluble natural products and are beneficial for the clinical effects improvement.