Effect of surface morphology of carrier lactose on dry powder inhalation property of pranlukast hydrate

The effects of surface morphology of carrier lactose on dry powder inhalation (DPI) property of pranlukast hydrate (PH) were investigated. The PH was mixed with 9-fold weights of carrier lactose, i.e. pharmatose 325M, 200M, DCL-11, DCL-21, spray dried amorphous (SDGa), -crystallized (SDGc) lactoses and fluidized bed granulated lactose (FBG) with various surface morphologies. These mixed powders were aerosolized by a Spinhaler(R) and in vitro deposition properties were evaluated by a twin impinger. Carrier lactose with higher specific surface area, i.e. surface roughness, like FBG emitted effectively PH particles from the inhalation device, whereas they reduced the respirable fraction captured in the twin impinger, resulting in lower inhalation efficiency, due to strong adhesion of PH to the carrier lactose. The SDGc having lots of microscopical projection on the surface increased the respirable particle percent of the emitted particles, improving the inhalation efficiency. The SDGa, smoothed sphere particle, did not so improve the inhalation efficiency as expected, owing to fairly strong adhesion between PH and lactose particles. Those finding indicated that the separation of drug particles from carrier lactose was a determining step to improve inhalation process for DPIs, as far as lactose particles emitted satisfactorily PH particles from the inhalation device. The surface morphology designed like SDGc, having fairly large surface area with microscopically increased surface roughness was desirable to improve inhalation property of DPI. (C) 1998 Elsevier Science B.V. All rights reserved.