Eclazolast (REV 2871 or CHBZ) is a non-disodium cromoglycate (DSCG)-like, antiallergic drug. Eclazolast is taken up by rat mast cells and human leukocytes in a specific and saturable manner. The compound can be hydrolyzed by a granule-associated enzyme in the mast cell to an ionic metabolite (REV 3579) whose in vitro profile is identical to that of DSCG. Eclazolast is a potent inhibitor of both immunologic and non-immunologic histamine release. It inhibits exocytosis by intracellularly affecting only direct Fc(epsilon)RI linked processes and not through inhibition of Ca2+ influx channels.