This study investigates the effects of a variety of coating materials on the flowability and dissolution of dry-coated cohesive ibuprofen powders, with the ultimate aim to use these in oral dosage forms. A mechanofusion approach was employed to apply a 1% (w/w) dry coating onto ibuprofen powder with coating materials including magnesium stearate (MgSt), L-leucine, sodium stearyl fumarate (SSF) and silica-R972. No significant difference in particle size or shape was measured following mechanofusion with any material. Powder flow behaviours characterised by the Freeman FT4 system indicated coatings of MgSt, L-leucine and silica-R972 produced a notable surface modification and substantially improved flow compared to the unprocessed and SSF-mechanofused powders. ToF-SIMS provided a qualitative measure of coating extent, and indicated a near-complete layer on the drug particle surface after dry coating with MgSt or silica-R972. Of particular note, the dissolution rates of all mechanofused powders were enhanced even with a coating of a highly hydrophobic material such as magnesium stearate. This surprising increase in dissolution rate of the mechanofused powders was attributed to the lower cohesion and the reduced agglomeration after mechanical coating.
Keywords: Dissolution; Fine cohesive powder; Ibuprofen; Mechanical dry powder coating; Mechanofusion; Powder flow.
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