The clinical implications of inhibition of the inducible form of cyclo-oxygenase.

There are 2 isoenzymes of cyclo-oxygenase (COX). There is a constitutive enzyme COX-1 which has a wide tissue distribution. In addition there is an inducible enzyme COX-2 which has a restricted tissue distribution. The inducible enzyme COX-2 is responsible for the generation of prostaglandins at sites of tissue inflammation and its inhibition is associated with an anti-inflammatory action. The constitutive enzyme, COX-1 is responsible for the production of prostaglandins with multiple functions. One well known and clinically important function is the gastroprotective effect of the prostaglandins produced in the gastric mucosa. While selective COX-2 inhibition may be associated with a reduced incidence of gastric adverse effects, a concern remains that its inhibition at other locations may be associated with other adverse effects.