Evaluation of classical NSAIDs and COX-2 selective inhibitors on purified ovine enzymes and human whole blood

Cyclooxygenase is the key enzyme in the biosynthesis of prostanoids, biolog ically active substances involved in several physiological processes and al so in pathological conditions such as inflammation. It has been well known for 10 years that this enzyme exists under two forms: a constitutive (COX-1 ) and an inducible form (COX-2). Both enzymes are sensitive to inhibition b y conventional non-steroidal anti-inflammatory drugs (NSAIDs). Observations were made that COX-1 was mainly involved in homeostatic processes, while t he COX-2 expression was associated with pathological conditions leading to the development of COX-2 selective inhibitors. Several methods have been re ported for the evaluation of the COX-1 and COX-2 inhibitory potency and sel ectivity of conventional or COX-2 selective NSAIDs. In this study, we evalu ated the COXs inhibitory profile of both conventional NSAIDs and COX-2 sele ctive inhibitors using two different in vitro methods: the first test was p erformed using purified enzymes while the second method consisted of a whol e blood assay. The results obtained with reference drugs in these two assay s will be discussed and compared in this article. (C) 2001 Harcourt Publish ers Ltd.