Some nonsteroidal antiinflammatory drugs inhibit the generation of superoxide anions by activated polymorphs by blocking ligand-receptor interactions.

Representatives of the major classes of nonsteroidal antiinflammatory drugs (NSAID) were assessed for their effects on superoxide anion (O2-.) production by human polymorphonuclear leukocytes stimulated with phorbol myristate acetate or N-formyl methionyl-leucyl phenylalanine (fMLP). Three levels of effects were studied: (1) overall inhibition of O2-. production, (2) the inhibition of interaction between fMLP and specific receptors at the cell surface, and (3) intermediate proenzyme and enzyme effects. Some, but not all drugs inhibited O2-. production. In general, drugs that inhibited O2-. production inhibited fMLP-receptor interactions in a consistent dose dependent fashion, showing noncompetitive kinetics. Drugs that failed to inhibit O2-. production showed weak and variable effects on receptor binding and on the intermediate enzymes. Clinical observations suggest that inflammation in diseases such as gout respond differently to NSAID than diseases such as rheumatoid arthritis; studies of drug effects may help to clarify the differences in pathogenesis of these inflammatory diseases.