Abstract: AimTo investigate the effects of surface modification of lactose carrier on performance of dry powder inhalations (DPIs). MethodsModified lactose surface was prepared using a “particle smoothing” process to obtain smooth carrier surface and low surface energy with the presence of magnesium stearate, colloidal silica dioxide and talc. Inverse gas chromatography (IGC) was used to assess the surface energy of treated lactose, and the in vitro deposition of carrier-based IFNa-2b DPIs was evaluated with twin stage impinger. ResultsThe flowing property of lactose was greatly improved and the surface energy decreased by the “particle smoothing” process. Decreasing surface energy resulted in greater aspiration fraction of IFNa-2b. ConclusionIGC is a potentially useful tool for rapid formulation design and screening.