Selectivity of various drugs with regard to inhibition of COX-1 and COX-2. IC50 values represent the mean of three or four determinations in whole blood assays. Drugs that appear below the diagonal line indicate preference for COX-2 inhibition over COX-1 inhibition. 6-MNA denotes 6-methoxy-2-naphthylacetic acid, the active metabolite of nabumetone. Updated from (2).