Abstract
Background: Severe asthma (SA) affects 5-8% of the asthma population but accounts for majority of the morbidity. Despite cough being a common symptom of asthma, it has rarely been studied in patients with SA. Its mechanism is poorly understood. This is partly due to the lack of safety data in using inhaled cough challenges. We performed a pilot study to investigate the safety of inhaled capsaicin challenge in patients with SA.
Method: Four inhalations of incremental doubling concentrations of capsaicin(0.48-1000mmol/L) were administered using a dosimeter, until the maximum tolerated concentration or final concentration was reached. Spirometry, Borg dyspnoea scale and visual analogue scale(dVAS) were assessed before and after, along with measuring the maximum number of coughs evoked at any dose(Emax) and the dose eliciting at least half this response(ED50). Participants were called at 48hrs, 72hrs and 7 days to capture adverse events(AEs).
Results: Patients were on British Thoracic Society steps 4/5. To date, eight(male n=4) participants have completed the capsaicin challenge with no significant drop in FEV1(>20%) post-challenge. The mean(range) change in FEV1 was -3.1%(-12.9,+7.6). Female patients coughed more than male patients and at lower concentrations(median: Emax 36 and 20; ED50 23.5 and 9.8mmol/L, respectively). Four patients requested salbutamol for symptoms despite no significant reduction in FEV1. The mean(range) change in dVAS and Borg scale were +11mm(-8,+32) and +0.9(0,2) respectively. Two patients reported AEs, but none were considered related to the challenge. No serious AEs were reported.
Conclusion: Our initial data suggests that inhaled capsaicin challenge is safe and tolerable in patients with SA.
Method: Four inhalations of incremental doubling concentrations of capsaicin(0.48-1000mmol/L) were administered using a dosimeter, until the maximum tolerated concentration or final concentration was reached. Spirometry, Borg dyspnoea scale and visual analogue scale(dVAS) were assessed before and after, along with measuring the maximum number of coughs evoked at any dose(Emax) and the dose eliciting at least half this response(ED50). Participants were called at 48hrs, 72hrs and 7 days to capture adverse events(AEs).
Results: Patients were on British Thoracic Society steps 4/5. To date, eight(male n=4) participants have completed the capsaicin challenge with no significant drop in FEV1(>20%) post-challenge. The mean(range) change in FEV1 was -3.1%(-12.9,+7.6). Female patients coughed more than male patients and at lower concentrations(median: Emax 36 and 20; ED50 23.5 and 9.8mmol/L, respectively). Four patients requested salbutamol for symptoms despite no significant reduction in FEV1. The mean(range) change in dVAS and Borg scale were +11mm(-8,+32) and +0.9(0,2) respectively. Two patients reported AEs, but none were considered related to the challenge. No serious AEs were reported.
Conclusion: Our initial data suggests that inhaled capsaicin challenge is safe and tolerable in patients with SA.
| Original language | English |
|---|---|
| Title of host publication | European Respiratory Journal |
| Pages | PA4404 |
| Volume | 52 |
| Edition | 56 |
| DOIs | |
| Publication status | Published - 19 Nov 2018 |
