There have been recent reviews of aspirin induced asthma (AIA),1 ,2 the use of the COX-2 preferential inhibitor nimesulide in asthmatic patients intolerant to non-steroidal anti-inflammatory drugs (NSAIDs),3 and of nimesulide in general.4 ,5 This paper discusses the importance of inhibiting prostaglandin E₂ (PGE₂) synthesis in AIA, and the relative safety of NSAIDs that preferentially inhibit COX-2.

Aspirin and other NSAIDs cause bronchoconstriction in about 10% of asthmatic subjects but NSAIDs relieve asthma in about 0.3%.2 This variability helps to show the complexity of the problem. Prostaglandins in human lung are formed by various tissues and cells, including bronchial muscle, epithelium, and inflammatory cells,1 ,2 so the inhibition of prostaglandin formation can have numerous effects. In addition, the prostanoids (prostaglandins and thromboxanes) formed have different, and sometimes opposite, effects on the lungs. Furthermore, NSAIDs may alter the synthesis of various prostaglandins differently in patients with AIA—for example, aspirin reduces the synthesis of PGE₂ but not of the bronchoconstrictors PGD₂ and PGF_2α.6 Inhibition of PGE₂synthesis seems to be particularly important in AIA for several reasons: PGE₂ can relax bronchial muscle, inhibit the formation or release of various bronchoconstrictor agents such as leukotrienes and histamine (levels of which are raised in patients with AIA), …