Concentration-effect relationships of NSAID.

For the most part, plasma concentrations of nonsteroidal antiinflammatory drugs (NSAID) have not correlated well with assessments of therapeutic response. This disappointing record may largely reflect weaknesses in experimental design. It may also be, however, that concentrations in plasma bear only a distant relationship to those in the inflamed tissues where NSAID presumably act. Elimination kinetics, protein binding, fat solubility, tissue blood flow, and uptake by cells may be determinants of concentration and response in target tissues. These factors are considered as they relate to NSAID concentrations in synovial effusions.