Selective prostaglandin G/H synthase (PGHS)-2 inhibitors show greater inhibitory activities on human PGHS-2 than on murine PGHS-2 in intact cells.

Excess eicosanoid formation during inflammation has been attributed to the expression of the gene coding for the inducible isoform of prostaglandin G/H synthase (PGHS-2). Human and murine PGHS-2 proteins differ in 73 out of the 604 amino acids. When comparing the inhibitory effects of a panel of PGHS-inhibitors in a whole cell human and murine PGHS-2 assay carried out under identical conditions, classical NSAIDs with the exception of aspirin and tenoxicam showed similar inhibitory effects on both human and murine PGHS-2 enzymes. However, the PGHS-2 selective inhibitors nimesulide, flosulide and NS398 showed a much greater inhibition of human PGHS-2. We suggest that these differences could be due to the genetic differences of human and murine PGHS-2.