(148b) Comprehensive Powder Flow Characterization with Reduced Testing

Powder flow is a critical attribute of pharmaceutical blends to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties. This study aims at characterizing different powder blends with a number of different rheological methodologies, in order to understand how particle physical attributes (namely morphology and size) and interaction between components within the formulation generate different responses when analysed by different rheological tests. Furthermore, this study intends on reducing the number of rheological tests in early development phases, by focusing on the tests that generate the maximum information about the flowability attributes of the pharmaceutical blends, avoiding redundant characterization. This work considered two cohesive powders - spray-dried hydroxypropyl cellulose (SD HPMC) and micronized indomethacin (IND) – formulated with other four commonly used excipients [(lactose monohydrated (LAC), microcrystalline cellulose (MCC), magnesium stearate (MgSt) and colloidal silica (CS)]. The experimental results showed that powder flowability may be affected by materials particles’ size, bulk density, morphology, and interactions with lubricant. In detail, parameters, such as angle of repose (AoR), compressibility percentage (CPS), and flow function coefficient (ff_c) have shown to be highly affected by the particle size of the materials present in the blends. On the other hand, the Specific Energy (SE) and the effective angle of internal friction (φe) showed to be more related with particle morphology and materials interaction with the lubricant. Since both ff_c and φe parameters are generated from the same yield locus test, data suggest that a number of different powder flow features may be understood only by applying this test, avoiding redundant powder flow characterization, as well as extensive time and material spent in early development formulation stages.