New selective COX-2 inhibitors

Conventional nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit both of the cyclooxygenase (COX-1 and COX-2) enzymes to varying degrees; consequently, they impair prostaglandin production in all tissues, causing adverse effects, especially in the gastrointestinal tract, respiratory system (aspirin-induced asthma), kidney and haematological system. Unfortunately, side-effects are common when contraindications to their use. The anti-inflammatory actions of the NSAIDs are mediated by COX-2 inhibition, while the adverse effects are considered to be predominantly caused by COX-1 inhibition. Therefore, the selective inhibition of COX-2 inhibitors offers real hope for safer NSAIDs; specific agents have now been developed to do this. Selective COX-2 inhibitors are effective anti-inflammatory agents, but their analgesic efficacy is still unclear. While they have significantly less gastrointestinal and antiplatelet effects, the acute renal and pulmonary effects of selective COX-2 inhibitors have not been fully clarified. Moreover, there are issues concerning their long-term safety because the inhibition of constitutive COX-2, which appears to have some important physiological functions, may still cause adverse effects.