Summary

It is crucial for dry powder inhaler formulations to exhibit satisfactory powder flow during production and administration. In this study, fine lactose carrier particles were modified by dry coating to alter their inter-particulate interactions therefore improve their powder flow. Six lactose samples with different size fractions were coated either with colloidal silica or magnesium stearate using either a mechanofusion processor or a conventional mixer. Powder flow behaviours were characterized using bulk densities and powder rheology methods. The greatest improvement in powder flow was obtained after mechanofusion treatment with magnesium stearate, as determined by both methods. Changes were the most significant for particles with mean size ranges 8-20 μm. Powder rheometry appeared to have strong potential in optimising powder flow for future studies