Bronchial asthma is a complex inflammatory disorder that involves acti
vation of, and mediator release by, a variety of cells including mast
cells. Nedocromil sodium can inhibit the activity of a range of inflam
matory cells including mast cells, as has been demonstrated in several
studies. In human beings nedocromil sodium inhibited histamine secret
ion from mast cells obtained by bronchoalveolar lavage and from disper
sed lung mast cells. Tachyphylaxis was noted with the latter cells onl
y. Because the bronchoalveolar lavage mast cells would come into direc
t contact with inhaled drugs, these cells may be a major target for th
e action of nedocromil sodium. The inhibitory effects of nedocromil so
dium on mast cell activation and secretion are one way the drug may be
effective in controlling airway obstruction.