Antiinflammatory and analgesic efficacy of COX-2 specific inhibition: from investigational trials to clinical experience.

Research strongly indicates that increased expression of the isoenzyme cyclooxygenase-2 (COX-2) is responsible for elevated production of prostaglandins in inflamed joint tissues and is involved in the mediation of pain. In contrast, COX-1 is a constitutively produced isoenzyme that is involved in the synthesis of eicosanoids that have important homeostatic functions, for example, in the gastric mucosa and platelets. This new knowledge led to the development of drugs that are highly specific inhibitors of COX-2 while not inhibiting COX-1 at maximally efficacious dosages. The first COX-2 specific agent approved for clinical use in the United States was celecoxib. Large multicenter trials have shown that celecoxib at dosages of 100 mg BID and 200 mg BID is as effective as naproxen 500 mg BID in patients with osteoarthritis of the knee or hip. Another large multicenter trial also demonstrated that celecoxib 200 mg BTD and 400 mg BID is as effective as naproxen 500 mg BID in patients with rheumatoid arthritis (RA). A comparative trial showed that celecoxib 200 mg BID is as effective as diclofenac SR 75 mg BID in patients with RA. The potential of COX-2 specific inhibitors to provide antiinflammatory and analgesic efficacy equivalent to that of conventional nonsteroidal antiinflammatory drugs without the adverse gastrointestinal mucosal and platelet effects associated with nonspecific COX inhibitors promises to revolutionize the clinical care of arthritis patients.