Modification of disodium cromoglycate passage across lung epithelium in vitro via incorporation into polymeric microparticles.

Two microparticle systems containing disodium cromoglycate (DSCG) alone or with polyvinyl alcohol (DSCG/PVA) were produced via spray drying and compared in terms of their physicochemical characteristics, aerosol performance and drug uptake across a pulmonary epithelial cell line (Calu-3), cultured under air interface conditions. The particle size distribution of DSCG and DSCG/PVA were similar, of spherical geometry, amorphous and suitable for inhalation purposes. Aerosolisation studies using a modified twin-stage impinger showed the DSCG/PVA to have greater aerosol performance than that of DSCG alone. Aerosol particles of DSCG and DSCG/PVA were deposited onto the surface of the Calu-3 air interface epithelium monolayer and the drug uptake from apical to basal directions measured over time. Drug uptake was measured across a range of doses to allow comparison of equivalent drug and powder mass deposition. Analysis of the data indicated that the percentage cumulative drug uptake was independent of the mass of powder deposited, but dependent on the formulation. Specifically, with the formulation containing DSCG, the diffusion rate was observed to change with respect to time (indicative of a concentration-dependent diffusion process), whilst DSCG/PVA showed a time-independent drug uptake (suggesting a zero-order depot release).