Double Particle Surface Modification to Improve Key Properties of Pueraria Lobatae Radix Powder for Direct Compaction

The ethanol extract of Pueraria lobatae Radix (EPL), a kind of medicinal herb powder with unacceptable behaviour (poor compactibility and slow dissolution rate), has the potential to be improved by double particle surface design by fluid-bed coating. This involves surface coating with plastic Hydroxypropyl Methylcellulose (HPMC) and surface pore formation induced by NH₄HCO₃.

The EPL drug was selected as the model for investigation. The formulation of the Composite Particles (CPs) was optimized using a central composite design. Subsequently, the pivotal tabletrelated attributes were contrasted between the optimized porous HPMC-coated EPL CPs and the pure HPMC-coated EPL CPs. Finally, the stability and applicability of the porous HPMC-coated EPL CPs were studied.

The results demonstrated that (i) the optimized use levels of HPMC and NH4HCO3 for the porous CPs were 8.42% and 15.00% (w/w), respectively; (ii) the compactibility and tablet dissolution rate of the porous HPMC-coated EPL CPs were significantly enhanced in comparison to those produced from the pure HPMC-coated CPs; and (iii) the porous HPMC-coated CPs exhibited good stability and universal applicability in direct compaction.

As a whole, the combination of polymeric coating and porous design proved effective in enhancing the compactibility and dissolution rate of EPL-based CPs while also rendering them suitable for direct compaction. These findings are conducive to the expansion of the application of fluidbed coating technology and the simultaneous improvement of the quality and efficacy of some drug tablets.