Formulating powder–device combinations for salmeterol xinafoate dry powder inhalers

[Display omitted] Using salmeterol xinafoate (SX) as an active pharmaceutical ingredient, the effects of carrier lactose particle type, total lactose fines content and device resistance on dry powder inhaler performance were investigated in vitro. To mimic drug levels in commercial preparations, interactive mixtures containing 0.58% w/w SX were prepared by low shear tumble mixing. Three types of milled inhalation grade lactose were used (Lactohale® LH 200, Respitose® ML006 and ML001) and the concentration of fine lactose (Lactohale® 300) added was varied. The in vitro deposition of each mixture was studied using a next generation impactor and inhaler devices exhibiting different resistances, Rotahaler®