Knowledge Center
Comprehensive powder flow characterization with reduced testing
Abstract
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 rheologic techniques, in order to understand how particles鈥 attributes 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 tests in early development phases, by selecting the ones that provide the best information about the flowability attributes of the pharmaceutical blends. This work considered two cohesive powders - spray-dried听hydroxypropyl cellulose听(SD HPMC) and micronized听indomethacin听(IND) 鈥 formulated with other four commonly used excipients [(lactose monohydrated (LAC),听microcrystalline cellulose听(MCC),听magnesium stearate听(MgSt) and听colloidalsilica听(CS)]. The experimental results showed that powder flowability may be affected by materials particles鈥 size, bulk density, morphology, and interactions with听lubricant. In detail, parameters, such as angle of repose (AoR), compressibility percentage (CPS), and flow function coefficient (ffc) 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 (蠁e) showed to be more related with particle morphology and materials interaction with the听lubricant. Since both ffc听and 蠁e parameters are generated from the听yield locus听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.
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