Improved direct compression properties of Gardeniae fructus water extract powders via fluid bed-mediated surface engineering

Direct compression (DC) attracts increasing attention for tablet manufacturing; however, its application in medicinal plant tablets is still extremely limited. In this work, eight kinds of the Gardeniae fructus water extract powder (GF)-based composite particles (CPs) were prepared with different cohesive surface engineering materials, including dextran, inulin, hypromellose, and povidone, alone or in combination with mannitol and colloidal silica. Their physical properties and compacting parameters were characterized comprehensively. All the CPs showed marked improvement in tabletability, which is about 2-4 times higher than that of GF and physical mixtures (PMs). Specifically, the CPs showed a 7.45-26.48 times higher hardness (Ha) value and a 1.26-2.74 times higher cohesiveness (Co) value than PMs. In addition, all the CPs (angle of repose being from 34.27° to 38.46°) showed better flowability than PMs (35.49° to 53.53°) and GF (51.86°). These results demonstrated that (i) fluid-bed coating was not a simple process of superposition and transmission of the physical properties of raw materials; and (ii) all the surface engineering materials studied could improve the DC properties of problematic GF to some degree. As a whole, through the design of fluid-bed coating CPs, qualified tablets with high GF loadings (up to 93%) were produced via DC.