Safety of capsaicin cough challenge testing.
BACKGROUND
Capsaicin, the pungent extract of red peppers, has achieved widespread use in clinical research because it induces cough in a dose-dependent and reproducible manner. Although > 2 decades of experience has led investigators to consider capsaicin cough challenge testing a safe diagnostic modality, this issue has not been specifically addressed in the literature.


OBJECTIVE
To review the published experience with capsaicin inhalation challenge testing in terms of safety.


METHODS
Literature review and personal communication with study authors.


METHODS
Academic medical center.


RESULTS
One hundred twenty-two published studies since 1984 described 4,833 subjects (4,374 adults, 459 children) undergoing capsaicin cough challenge, with no serious adverse events reported. Subjects included healthy volunteers as well as patients with asthma, COPD, pathologic cough, and other respiratory conditions. Minor complaints described in a small fraction of studies consisted mainly of transient throat irritation. Personal communication with the authors of > 90% of the studies confirmed an absence of any serious adverse events. Furthermore, these investigators have performed thousands of additional capsaicin challenge studies not reported in the literature, also without any associated serious adverse events.


CONCLUSIONS
A review of the 20-year clinical experience has failed to uncover a single serious adverse event associated with capsaicin cough challenge testing in humans. Given the need for better antitussive therapies, capsaicin represents a vital component of future scientific inquiry in the field of cough.
Dicpinigaitis
Peter V
PV
Einstein Division/Montefiore Medical Center, Albert Einstein College of Medicine, 1825 Eastchester Road, Bronx, NY 10461, USA. pdicpinigaitis@pol.net
Alva
Rakesh V
RV
D000280:Administration, Inhalation; D001985:Bronchial Provocation Tests / Q000379:methods*; D002211:Capsaicin / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D003371:Cough / Q000139:chemically induced*; D004305:Dose-Response Relationship, Drug; D006801:Humans
D002211:Capsaicin