Clinical experience with specific COX-2 inhibitors in arthritis.

The common mechanism of action of aspirin and the chemically unrelated non-steroidal anti-inflammatory drugs (NSAIDs) is the inhibition of prostaglandin (PG) production due to interference with the enzymatic activity of cyclooxygenase (COX). These agents have long been used as effective treatments for arthritis. The recognition that the inducible isoform COX-2 was associated with inflammation and arthritis led to the hypothesis that PGs produced by a COX-2-dependent pathway were responsible for the inflammation, pain, and tissue destruction. Since the constitutive COX-1 enzyme was identified as responsible for gastroprotection and inhibition of platelet function, the potential for compounds that were both effective and safer than NSAIDs led to rapid development of agents that specifically inhibit COX-2. These agents have now been tested and approved for use by the US Food and Drug Administration for patients with osteoarthritis and rheumatoid arthritis. They have been shown equally effective to comparitor NSAIDs. More importantly, there is a 3.5-fold reduction in the incidence of endoscopic gastroduodenal ulcerations and early data suggesting a similar reduction in clinically significant perforations, symptomatic ulcers, and bleeds. In patients with arthritis at risk for gastrointestinal complications of NSAIDs, specific inhibitors of COX-2 provide an effective and apparently safer form of anti-inflammatory agent.