Beclomethasone dipropionate attenuates airways hyperresponsiveness to neurokinin A and histamine in asthma.

BACKGROUND

Inhaled corticosteroids (ICS) are the most effective anti-inflammatory agents available for the treatment of asthma but they produce only modest effects on airway inflammation and non-specific bronchial hyperresponsiveness (BHR). However, little is known about the possibility that treatment with ICS might cause additional protection on BHR to inhaled tachykinins such as neurokinin A (NKA).

OBJECTIVE

Therefore, we compared the effects of beclomethasone dipropionate (BDP) on the degree of BHR to inhaled histamine and NKA in a double-blind, controlled, cross-over study of asthmatic patients.

METHODS

Patients attended the laboratory before and after each 6 weeks treatment period to undertake concentration-response studies with histamine and NKA. Bronchial responsiveness to both funs was expressed as the provocative concentration producing a 20% decrease in FEV(1) from baseline (PC(20)).

RESULTS

BDP therapy attenuated the constrictor response to both agonists to a similar degree, their geometric mean (range) PC(20) values increasing from 0.47 (0.21-1.41) mg/ml to 2.43 (0.51-4.50) mg/ml (P<0.01, post-salb vs. post-BDP treatment) and from 101.7 (27.3-356.1) microg/ml to 666.7 (151.5-1,000) microg/ml (P<0.01, post-salb vs. post-BDP treatment) for histamine and NKA, respectively.

CONCLUSION

Airway responsiveness to histamine and NKA is reduced by BDP to the same extent. As a result of these findings, provocation with NKA is unlikely to provide additional useful information in the assessment of airway inflammation in asthma.