Abstract
Background: Capsaicin (CAP), Citric Acid (CA), Fog and ATP cough challenges have been routinely used to assess cough reflex sensitivity (CRS). Whether these agents can be utilised on a single challenge protocol or if cross-tachyphylaxis prevents the accurate determination of challenge sensitivity is unknown.
Aim: To determine whether order of cough challenge effects CRS.
Methods: CRS was studied in 23 chronic cough (CC) and 12 healthy volunteers. Cough challenges were performed in a random sequence and in accordance with ERS guidelines. The first challenge with each agent was then compared with subsequent challenges. C2 was log transformed (logC2) and compared by ANOVA.
Results: First challenge did not influence the logC2 concentration of subsequent challenges (Table 1). This was also the case when CC and healthy volunteers were analysed separately. However, all three chemical agents caused significantly greater response in chronic cough patients. Mean difference in logC2 concentrations for CAP, CA and ATP were 0.64 (95% CI 0.25 – 1.03), 0.90 (95% CI 0.36 -1.44), 1.02 (95% CI 0.39 – 1.65) all p < 0.01 respectively.
Conclusion: First cough challenge did not effect subsequent cough CRS. Protocols using multiple challenge methodology may be used to assess pharmacodynamics and target engagement of anti-tussive drugs.
Table 1. Values for mean (± SD) logC2, grouped by the first cough challenge performed.
Footnotes
Cite this article as: European Respiratory Journal 2018 52: Suppl. 62, PA4438.
This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).
- Copyright ©the authors 2018