Tiotropium attenuates refractory cough and capsaicin cough reflex sensitivity in patients with asthma

Publication date: Available online 3 February 2018
Source:The Journal of Allergy and Clinical Immunology: In Practice
Author(s): Kensuke Fukumitsu, Yoshihiro Kanemitsu, Takamitsu Asano, Norihisa Takeda, Hiroya Ichikawa, Jennifer Maries Go Yap, Satohi Fukuda, Takehiro Uemura, Osamu Takakuwa, Hirotsugu Ohkubo, Ken Maeno, Yutaka Ito, Tetsuya Oguri, Atsushi Nakamura, Masaya Takemura, Akio Niimi
BackgroundAsthmatic cough is often refractory to standard treatments such as inhaled corticosteroids and long-acting β2 agonists (ICS/LABA). Tiotropium may modulate cough reflex sensitivity of acute viral cough, but its efficacy in asthmatic cough remains unknown.ObjectiveTo evaluate whether tiotropium improves cough and cough reflex sensitivity in asthmatic patients refractory to ICS/LABA.MethodsSeventeen consecutive asthmatic patients with chronic cough despite the use of ICS/LABA [13 females; 43.4 (19.0) years-old; average ICS dose 651 (189) μg/day, fluticasone equivalent] were additionally treated with tiotropium (5 μg/day) for 4 to 8 weeks to examine its effects on pulmonary function and capsaicin cough reflex sensitivity (cough thresholds; C2 and C5). Cough severity, cough-specific quality of life, and asthma control were also evaluated using cough visual analog scales (VAS), the Japanese version of Leicester Cough Questionnaire (J-LCQ), and Asthma Control Test (ACT), respectively. Patients with an improved cough VAS of ≥15 mm were considered responders to tiotropium.ResultsTiotropium significantly improved cough VAS, J-LCQ, and ACT scores, but not forced expiratory volume in 1 second (FEV1). Changes in cough VAS correlated with those in C2 (r=-0.58, p=0.03), C5 (r=-0.58, p=0.03), and ACT scores (r=-0.62, p=0.02), but not in FEV1 in the overall patients. When analyses were confined to the 11 responders, tiotropium significantly improved capsaicin cough reflex sensitivity within the subgroup (C2: p=0.01 and C5: p=0.02), and versus the non-responders (C2: p=0.004 and C5: p=0.02).ConclusionTiotropium may alleviate asthmatic cough refractory to ICS/LABA by modulating cough reflex sensitivity but not thorough bronchodilation.