Dry granulation of vitamin D3 and iron in corn starch matrix: Powder flow and structural properties

In this work, a twin-screw dry granulation (TSDG) was adopted to produce vitamin D3 (VD3) and iron blended dry granules using corn starch as an excipient. Response surface methodology was applied to determine the effect of the formulation compositions (VD3 and iron) on granule properties [tapped bulk density, oil holding capacity, and volumetric mean particle size (D_v50)]. Results indicated that the model fitted well, and responses, in particular flow properties, were significantly affected by the composition. The D_v50 was only influenced by the addition of VD3. The flow properties were characterized by the Carr index and Hausner ratio, which indicated very poor flow of the granules. Scanning electron microscopy with energy dispersive spectroscopy confirm the presence and distribution of Fe⁺⁺ and VD3 in the granules. Overall, TSDG was proven to be a simple alternative method for the preparation of dry granules of VD3 and iron in a blend.