S54 Thorax 2000;55 (Suppl 2):S54–S56 Thorax: first published as 10.1136/thorax.55.suppl_2.S54 on 1 October 2000. Downloaded from The importance of COX-2 inhibition for aspirin induced asthma Alan Bennett There have been recent reviews of aspirin “specific” is used here to denote that the activ- induced asthma (AIA),12 the use of the ity is (usually) much greater against COX-2 COX-2 preferential inhibitor nimesulide in than against COX-1. Two drugs with a asthmatic patients intolerant to non-steroidal “preferential” status are nimesulide and mel- anti-inflammatory drugs (NSAIDs),3 and of oxicam, whereas two drugs that probably nimesulide in general.45 This paper discusses deserve the title “specific” are rofecoxib and the importance of inhibiting prostaglandin E2 celecoxib. (PGE2) synthesis in AIA, and the relative Nimesulide (4-nitro-2-phenoxymethane- safety of NSAIDs that preferentially inhibit sulphonanilide) is particularly important in COX-2. AIA because several studies have shown that it Aspirin and other NSAIDs cause broncho- is tolerated by most patients with the disorder constriction in about 10% of asthmatic to about the same extent as paracetamol. This subjects but NSAIDs relieve asthma in about sulphonanilide NSAID, which is eVective in 0.3%.2 This variability helps to show the com- treating a wide spectrum of inflammatory and plexity of the problem. Prostaglandins in painful conditions,7 was first marketed in 1985 human lung are formed by various tissues and and 10 years later it was found to be a cells, including bronchial muscle, epithelium, preferential inhibitor of COX-2.89Because it is and inflammatory cells,12 so the inhibition of not marketed in the USA, Japan, or the UK, prostaglandin formation can have numerous nimesulide is not well known in some parts of eVects. In addition, the prostanoids (prosta- the world. Nevertheless, in the 50 countries glandins and thromboxanes) formed have dif- where it is now sold, nimesulide is often the ferent, and sometimes opposite, eVects on the first or second NSAID in the local market, and lungs. Furthermore, NSAIDs may alter the it is fifth worldwide despite being absent from synthesis of various prostaglandins diVerently the largest markets. in patients with AIA—for example, aspirin In every study of COX selectivity nimesulide reduces the synthesis of PGE2 but not of the was more potent against COX-2 than COX-1. 6 bronchoconstrictors PGD2 and PGF2á. Inhi- However, as with all NSAIDs, its COX-1/ bition of PGE2 synthesis seems to be particu- COX-2 ratio varies in diVerent reports (from 9 larly important in AIA for several reasons: about 4.5 to 2500 in favour of COX-2). http://thorax.bmj.com/ PGE2 can relax bronchial muscle, inhibit the Factors influencing the ratio include the formation or release of various broncho- enzyme source, cell type, substrate concentra- constrictor agents such as leukotrienes and tion, and incubation time. histamine (levels of which are raised in Our own investigations were on COX-1 and patients with AIA), and PGE2 administered COX-2 sheep pure enzymes, and human as an aerosol inhibits aspirin induced gastric mucosa (constitutive COX-1) and bronchoconstriction.12 leucocytes (induced COX-2).8 We found that Since PGE2 and other prostanoids are COX-1 from sheep seminal vesicles was not formed by both constitutive COX-1 and inhibited by nimesulide, in contrast to the on September 26, 2021 by guest. Protected copyright. induced COX-2, the eVect on the lung may concentration-related inhibition by indometh- partly reflect the relative activities of each acin, naproxen, piroxicam, ibuprofen, tolmetin, NSAID on the enzymes. Generally, in various and diclofenac. COX-2 from sheep placenta tissues and organs such as the gastrointestinal was blocked by all the NSAIDs. In our human mucosa and kidney, COX-1 produces prosta- in vitro studies nimesulide blocked COX-2 in glandins that have physiological protective leucocytes, but only weakly inhibited COX-1 in roles, whereas COX-2 induced at sites of isolated gastric mucosa. Similarly, with human inflammation forms prostaglandins that subjects nimesulide inhibited leucocyte contribute to the disease. It is generally COX-2 to a considerable extent but had little agreed that blocking COX-1 can damage the eVect on COX-1 in the gastric mucosa and stomach and kidneys, at least when other fac- platelets.10 tors are involved, and perhaps this applies to the lungs. Nimesulide Academic Department Since nimesulide was initially thought to act of Surgery, The Rayne mainly by non-prostaglandin mechanisms Institute, Guy’s, King’s COX-2/COX-1 inhibition in relation to and St Thomas’ AIA (before it was realised that tissue containing Medical School, Examination of the relative importance of COX-1 was used to measure inhibition of London SE5 9NU, UK COX enzymes in AIA can be partly assessed prostaglandin synthesis11), nimesulide was A Bennett from studies using preferential COX-2 inhibi- tested in patients who could not tolerate tors. The term “preferential” is used here to other NSAIDs. The studies summarised in Correspondence to: Professor A Bennett denote activity that is somewhat greater against table 1 show that nimesulide can be tolerated [email protected] COX-2 than against COX-1, whereas the term by most patients with AIA. It can usually www.thoraxjnl.com Importance of COX-2 inhibition for aspirin induced asthma S55 Thorax: first published as 10.1136/thorax.55.suppl_2.S54 on 1 October 2000. Downloaded from Table 1 Tolerance data on nimesulide in AIA Thus, the usual lack of bronchial problems with nimesulide in patients with AIA might Patients tolerating Nimesulide dose (mg) nimesulide (%) Reference result partly from these other pharmacological actions. Meloxicam has also been reported to 100 20/20 (100%) 12 have non-prostaglandin activity and this might 100 20/20 (100%) 13 400 18/20 (90%) 13 become relevant to the present discussion if the 200 46/50 (92%) 14 drug is found in larger studies to be relatively 100 7/12 (58%) 15 safe in AIA. The picture should be clarified in Nimesulide was started at a low dose and then increased to the due course by examination of the selective amount shown. The usual anti-inflammatory dose is 100 mg COX-2 inhibitors rofecoxib and celecoxib. It twice daily. In the study by Bianco et al13 the 20 patients were the same in the 100 mg and 400 mg groups. remains to be seen how much COX-1 activity is needed to allow production of prostaglandins Table 2 Tolerance data on nimesulide in patients with other for physiological functions, and whether a symptoms of NSAID intolerance small inhibition of COX-1 added to a stronger eVect on COX-2 might be beneficial in reliev- Patients tolerating Nimesulide dose (mg) nimesulide (%) Reference ing inflammatory processes that contribute to asthma and other diseases. 500 (over 84 h) 86/92 (93%) 16 200 39/42 (93%) 17 100 270/284 (95%) 18 1 Szczeklik A, Stevenson DD. Aspirin-induced asthma: 200 83/87 (95%) 19 advances in pathogenesis and management. J Allergy Clin 200 415/429 (97%) 20 Immunol 1999;104:5–13. 175 14/15 (93%) 21 2 Gryglewski RJ. Aspirin-induced asthma and cyclooxygen- 100 7/8 (88%) 15 ases. In: Vane J, Botting J, eds. Selective COX-2 inhibitors. Pharmacology, clinical eVects and therapeutic potential. Wil- Nimesulide was started at a low dose and then increased to the liam Harvey Press and Kluwer Academic Publishers, 1998: 99–107. amount shown. The usual anti-inflammatory dose is 100 mg 3 Senna GE, Passalacqua G, Andri G, et al. Nimesulide in the twice daily. Symptoms in the few patients showing some intoler- treatment of patients intolerant of aspirin and other ance to nimesulide were often mild. NSAIDs. Drug Safety 1996;14:94–103. 4 Bennett A. Overview of nimesulide. Rheumatology 1999; 38(Suppl 1):1–3. be given without any problems to patients 5 Bennett A, Villa G. Nimesulide: a nonsteroidal anti- inflammatory drug that preferentially inhibits with other symptoms of NSAID intolerance cyclooxygenase-2, and has various unique pharmacological such as urticaria and/or angio-oedema activities. Expert Opinion on Pharmacotherapy 2000;1:277– (table 2). 86. 6 Szczeklik A, Sladek K, Dworski R, et al. Bronchial aspirin challenge causes specific eicosanoid response in aspirin- sensitive asthmatics. Am J Respir Crit Care Med 1996;154: 1608–14. Meloxicam 7 Bennett A, Berti F, Ferreira SH. Nimesulide: a multifacto- Only one small study has been reported on the rial therapeutic approach to the inflammatory process? Drugs 1993;46 (Suppl 1). use of meloxicam in patients with AIA. In five 8 Tavares IA, Bishai PM, Bennett A, Activity of nimesulide on NSAID intolerant patients dyspnoea occurred constitutive and inducible cyclo-oxygenases. Arzneimittel- Forschung 1995;45:1093–6. in two with aspirin and two with ketoprofen, 9 Famaey J-P.In vitro and in vivo pharmacological evidence of but three of these four had no dyspnoea with selective cyclooxygenase-2 inhibition by nimesulide: an overview. Inflamm Res 1997;46:437–46. http://thorax.bmj.com/ 11 mg meloxicam (therapeutic dose 7.5– 10 Shah AA, Murray FE, Fitzgerald DJ. The in vivo assessment 15 mg daily).22 of nimesulide cyclooxygenase-2 selectivity. Rheumatology 1999;38(Suppl 1):19–23. 11 Magni E. The eVect of nimesulide on prostanoid formation. Drugs 1993;46(Suppl 1):10–14. Celecoxib and rofecoxib 12 Robuschi M, Refini M, Sturman et al. La nimesulide non induce asma in pazienti asmatici FANS intolleranti. These new selective COX-2 inhibitors have not Proceedings of an International Symposium on Advances in yet been examined in AIA and are currently Pneumology and Cardiology. Bologna: Monduzzi Publishers, 1987: 431–5.