An integrated material-sparing method for determining dilution potential of direct compression tablet fillers

An ideal filler for direct compression (DC) formulation requires both good flowability and compactibility. To ensure consistent tablet quality across various APIs and API loadings, as well as successful manufacturability, it is essential to understand the “dilution potential” of any DC tablet filler. In this study, an integrated material-sparing laboratory-scale method was developed to evaluate the dilution potential of a co-processed glutinous rice starch (CP-GRS) using two grades of acetaminophen (APAP) and ibuprofen (IBN) as model drugs. This method considers three criteria pertaining to tablet performance and manufacturability: (1) <1 % weight loss for the friability, (2) a disintegration time (DT) of <15 min, and (3) superior flowability compared to microcrystalline cellulose (Avicel® PH102). The maximum drug loading at the appropriate critical pressure (P_c) was determined, indicating the dilution potential. The results showed that granular APAP (gAPAP) could be loaded up to 34 % in CP-GRS at a compaction pressure of ∼240 MPa, fine APAP achieved a loading of 20 % in the range of 143–288 MPa, and IBN reached a maximum API loading of 40 % within the 115–150 MPa range. This integrated method, by minimizing material consumption, can also be applied to enable efficient DC formulation development of an API of interest during an early drug development phase.