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Powder vmd3/13/2023 ![]() ![]() “Mechanofusion” is a term used for intensive dry coating approaches that have gained interest for particle and powder modification. In general, dry coating is an attractive approach, as it is simpler, cheaper, safer and more environment-friendly than solvent-based alternatives. Recently, selected dry coating techniques have been used to improve the flowability of cohesive powders by modifying their inter-particulate interactions. Hence, glidant is difficult to deposit and disperse onto individual host particle surfaces. In such cases, conventional mixing may not provide enough energy to break the host particle agglomerates and expose host particle surfaces to glidant guest particles. However, such glidant particles with very small particle sizes (typically < 1 μm) tend to have poor flow themselves and can be difficult to readily disperse onto host particle surfaces uniformly, especially, for fine host particles smaller than 50 μm which commonly form strongly agglomerated structures. This approach can improve powder flow for some cohesive powders. It is believed to act as guest particles on the surface of host particles which then reduces cohesive and frictional forces between host particles. ![]() Fumed silica is probably the most widely used glidant in pharmaceutical formulations. īesides aeration and vibration, addition of glidants is a common approach used to improve the flow of solid formulations. Handling cohesive powder containing fine particles is a generic industrial problem since such powders exhibit poor flowability due to the strong inter-particle attractive forces associated with small particle sizes. Notably, powder flowability is highly influential and often the major issue with particulate handling and processing. In pharmaceutical and related industries, product performance is often based on powder flow or de-agglomeration behaviours, where fine cohesive powder is common: for example, to fill a tablet die, to fluidise in a coater, to empty a sachet, or to re-suspend a powder from an inhaler. Particulate handling plays a fundamental part in industrial manufacturing operations. This study demonstrated that an optimised mechanofusion process is an efficient and effective approach for substantially improving flow of fine cohesive powders to achieve equivalent flow behaviours of much larger sized powders. At an appropriate coating speed, optimal coating can be achieved after processing for 5 min for P450. The improvement in powder flow behaviours was shown to be dependent on coating parameters such as coating speed and coating time duration. Of particular note, the originally non-flowing cohesive powder P450 with VMD approximately 20 μm achieved free-flowing characteristics and was as flowable as R010 after mechanofusion. The bulk densities for all cohesive powders increased and flow behaviours were improved substantially except for the already free-flowing powder of R010 (with VMD approximately 120 μm). Various commercial fine lactose powders with particle size range from approximately 4 to 120 μm were dry coated with magnesium stearate using a recently optimised mechanofusion approach. The aim of this study was to evaluate the effect of an intensive dry coating process on the improvement in flow behaviours for fine cohesive lactose powders as a function of size distribution and coating process parameters. ![]()
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