ABSTRACT
Solid dispersion, a dispersion system in which drug molecules are highly dispersed in carrier materials, has been commonly used to improve the solubility and dissolution rate of poorly soluble drugs. The miscibility between drug and carrier is crucial to improve the dissolution performance and stability of solid dispersion. Therefore, the selection of carrier types and the optimization of drug loading are very important. In the current study, the solubility parameter method and Flory-Huggins theory were used to predict the miscibility between olaparib (OLP) and different carriers (VA64, Soluplus, Plasdone S630 and Kollidon K29/32). Besides, the carrier material with good miscibility was experimentally screened by differential scanning calorimetry (DSC). The optimum of drug-carrier ratio was further performed based on the miscibility phase diagram of drug and carrier. Theoretical calculation and experimental evaluation showed that the miscibility of OLP and VA64 was the best, and the drug loading of 30% could meet the requirements of large drug loading and physical stability. Polarizing light microscope, X-ray powder diffraction, DSC and laser confocal Raman spectroscopy exhibited that OLP was amorphous form in the solid dispersion system. Powder dissolution test demonstrated that the solid dispersion showed significantly enhanced dissolution rate in comparison to crystalline OLP. In this study, theoretical calculation and experimental evaluation were used to screen the types of carriers and optimize the drug loading, which provides an efficient strategy for the selection of carrier and the amount used in solid dispersion.