Salbutamol Sulphate absorption across Calu-3 bronchial epithelia cell monolayer is inhibited in the presence of common anionic NSAIDs

Purpose: The aim of this study was to characterize the permeability kinetics of salbutamol sulphate, a commonly used 2-agonist in the treatment of asthma exacerbation, across Calu-3 respiratory epithelial cell monolayers in the presence of non-steroidal anti-inflammatory drugs (NSAIDs), as they have been implicated to be able to modulate organic cation transporters (OCT). Methods: Calu-3 cell monolayers were grown in a liquid covered culture (LCC) configuration on 0.33 cm2 Transwell polyester cell culture supports. Monolayers, cultured between 11 and 14 days were evaluated for epithelial resistance, tight junction integrity and expression of OCT using Western blot analysis. The transport of salbutamol across the monolayer was studied as a function of concentration.  Directional transport was investigated by assessing apical-basal (a-b) and basal- apical (b-a) directions. The influence of a non-specific OCT inhibitor (tetraethylammonium, TEA) and three NSAIDs (aspirin, ibuprofen and indomethacin) on the uptake of salbutamol was studied. Results: The flux of salbutamol sulphate increased with increasing concentration, before reaching a plateau suggesting the involvement of a transport mediated uptake mechanism. Western blot analysis detected the presence of OCT1-3 and N1 and N2 sub-types suggesting the presence of functioning transporters. The apparent permeability (Papp) of 0.1 mM salbutamol across the epithelial monolayer displayed directional transport in the a-b direction which was inhibited by  ~70% in the presence of TEA, suggesting OCT mediated uptake. Likewise, the uptake of 0.1 mM salbutamol was decreased in the presence of all three NSAIDs supporting a mechanism whereby NSAIDs inhibit absorption of salbutamol across the bronchial epithelium via effects on the OCT transporters.