Inhibitory effect of epinastine on superoxide generation by rat neutrophils

We studied the effects of antiallergic drugs, epinastine, ketotifen, oxatomide, mequitazine and cromolyn sodium on superoxide anion (O2-) generation from rat neutrophils. Epinastine, ketotifen, oxatomide and mequitazine dose-dependently prevented the N-formyl-Met-Leu-Phe- and phorbol 12-myristate 13-acetate-induced O2- generation, but cromolyn sodium did not prevent it. When membrane and cytosol fractions were incubated with each drug, epinastine, ketotifen and mequitazine prevented O2- generation. On the other hand, when only the membrane fraction was incubated with each drug, ketotifen and mequitazine prevented O2- generation, but epinastine did not. Epinastine may inhibit the NADPH oxidase system through the obstruction of NADPH oxidase-associated cytosol components.