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QA/QA0 = (1-尾) + 尾*exp(-纬*L*FHeadspace*r)
where QA0 is initial quality attribute value, 尾 is sensitivity of the QA to lubrication, 纬 is formulation-specific lubrication rate constant, L is characteristic mixing length scale, FHeadspaceis the blender headspace fraction, and r is the number of blending cycles.
2:1 blends of microcrystalline cellulose and spray-dried lactose or dibasic calcium phosphate were mixed with 1% magnesium stearate using Turbula bottle blenders and pilot/commercial scale blenders, varying blender volume, V, (30-1250 ml; 100-2000 Liters); Fheadspace(30, 70%); and r (24 to ~190,000 cycles). Tablets were manufactured using a Huxley-Bertram compaction simulator to evaluate the change in tablet tensile strength as a function of the extent of lubrication mixing. Other attributes of the blends/tablets were also evaluated including compressibility, bulk/tapped density, friability, and disintegration.
The validity of the proposed lubrication blending process scale-up model was shown for blenders from 30-ml to 2000-liter (an approximately five order of magnitude change in scale) for both placebo formulations. This validated scale-up model can be used to replace commercial-scale experiments with bench-scale, material-sparing experiments to support QbD lubrication blending process understanding and design space verification.