features of COX-I inhibitors?

Answer 1

"The enzymes cyclooxygenase-1 and cyclooxygenase-2 (COX-1 and COX-2) catalyze the conversion of arachidonic acid to prostaglandin (PG) H2, the precursor of PGs and thromboxane. These lipid mediators play important roles in inflammation and pain and in normal physiological functions. While there are abundant data indicating that the inducible isoform, COX-2, is important in inflammation and pain, the constitutively expressed isoform, COX-1, has also been suggested to play a role in inflammatory processes. To address the latter question pharmacologically, we used a highly selective COX-1 inhibitor, SC-560 (COX-1 IC50 = 0.009 μM; COX-2 IC50 = 6.3 μM). SC-560 inhibited COX-1-derived platelet thromboxane B2, gastric PGE2, and dermal PGE2 production, indicating that it was orally active, but did not inhibit COX-2-derived PGs in the lipopolysaccharide-induced rat air pouch. Therapeutic or prophylactic administration of SC-560 in the rat carrageenan footpad model did not affect acute inflammation or hyperalgesia at doses that markedly inhibited in vivo COX-1 activity. By contrast, celecoxib, a selective COX-2 inhibitor, was anti-inflammatory and analgesic in this model. Paradoxically, both SC-560 and celecoxib reduced paw PGs to equivalent levels. Increased levels of PGs were found in the cerebrospinal fluid after carrageenan injection and were markedly reduced by celecoxib, but were not affected by SC-560. These results suggest that, in addition to the role of peripherally produced PGs, there is a critical, centrally mediated neurological component to inflammatory pain that is mediated at least in part by COX-2." (1)

"VANDERBILT: A surprising new scientific finding may hold answers to better treatment or prevention of ovarian cancer and will certainly alter the course of cancer research.
"Research being published Saturday in the journal Cancer Research shows that the enzyme COX-1, and not the COX-2 enzyme, which is a current target of therapy, is expressed in epithelial ovarian cancer tissue samples isolated from women.

"This finding, by researchers at Vanderbilt University Medical Center in Nashville, may suggest a new direction in cancer care -- using drugs that aim to block both COX-1 and COX-2 or drugs that block COX-1 alone. "This could have a significant clinical impact with regard to our thinking about ovarian cancer," said co-investigator Raymond DuBois, M.D., Ph.D." (2)

"Cox-1: Cyclooxygenase-1, a protein that acts as an enzyme to speed up the production of certain chemical messengers, called prostaglandins, within the stomach. The prostaglandins work within certain cells that are responsible for inflammation and other functions. For example, they promote the production of the natural mucus lining that protects the inner stomach. Cox-1 is normally present in a variety of areas of the body, including not only the stomach but any other site of inflammation." (3)