Cyclooxygenase (COX), an essential enzyme in the pathway of prostaglandin formation from arachidonic acid, exists in two isoforms. Cyclooxygenase-1 (COX-1) is expressed under normal physiologic conditions, whereas COX-2, the inducible isoform, is associated with inflammation. Recent studies have linked COX-2 induction to the asthmatic inflammatory response, but potentially beneficial results, such as enhanced production of antiinflammatory and bronchoprotective substances, may also occur. The aim of the present study was to investigate the effect of selective COX-2 inhibition on bronchial responsiveness and cough reflex sensitivity. Eight adult subjects with stable asthma underwent spirometry, bronchoprovocation challenge with methacholine, and cough challenge testing with capsaicin, before and after a 7 day course of the COX-2 inhibitor celecoxib (200 mg orally, twice daily) and placebo, in a randomized, double-blind, crossover fashion. No significant changes in pulmonary function, bronchial responsiveness, or cough reflex sensitivity were induced by celecoxib. It appears, therefore, that 1 week of therapy with celecoxib does not significantly affect basal airway tone, nor the afferent airway receptors controlling bronchoconstriction and cough. However, the results of this trial cannot be extrapolated to subjects with severe asthma, or those suffering an asthmatic exacerbation. In such conditions of enhanced inflammatory response, the role of selective COX-2 inhibition remains to be elucidated.
Copyright Academic Press.