Influence of the Lactose Grade within Dry Powder Formulations

Dry powder formulations are often composed of fi ne drug particles and coarser carrier particles, typically -lactose monohydrate because it is an inert, cheap, broadly available and non-toxic excipient1. However, the effi ciency of a powder formulation may be highly dependent on the lactose quality and source2. Indeed, interactions between particles are mainly dependent on the physicochemical characteristics of the interacting particles. The aim of this work was to identify the characterisitcs of lactose that infl uence the drug-to-carrier interaction and the performance of dry powder formulation. For this purpose, we compared marketed lactoses obtained by milling or by sieving. From the same raw materials, 2 fractions of lactose without fi nes were also prepared and tested.