Safety of Capsaicin Cough Challenge Testing

Antitussive Drugs—Past, Present, and Future

“…On the other hand, the C-fibers involved in the cough reflex are relatively insensitive to mechanical stimuli and lung stretch but are activated by bradykinin and by agonists of the ionotropic receptors, transient receptor potential vanilloid 1 (TRPV 1 ) (capsaicin, resiniferatoxin, protons), and transient receptor potential A1 (TRPA1) (allyl isothiocyanate, acrolein, cinnamaldehyde). These chemical stimuli have been shown to evoke coughing in animals and in humans (Canning et al, 2004;Dicpinigaitis and Alva, 2005;Birrell et al, 2009;Grace et al, 2012). Single cell polymerase chain reaction analyses confirm the expression of TRPV 1 and TRPA 1 in the neurons projecting these bronchopulmonary C-fibers in animal lungs (Nassenstein et al, 2008;Brozmanova et al, 2012), and TRPV 1 has been localized to nerve terminals in human airways (Groneberg et al, 2004).…”

ERS guidelines on the assessment of cough

“…A recent review of the 20-yr clinical experience with capsaicin failed to uncover a single serious adverse event associated with capsaicin cough challenge testing in humans [46]. This review included an examination of 122 studies published since 1984, describing 4,833 subjects, including healthy adults and children, as well as patients with pathological cough, asthma, COPD, hypertension, gastro-oesophageal reflux disease, interstitial lung disease, acute upper respiratory tract infection, cervical spinal cord injury, heart-lung transplantation and cystic fibrosis [46].…”

“…This review included an examination of 122 studies published since 1984, describing 4,833 subjects, including healthy adults and children, as well as patients with pathological cough, asthma, COPD, hypertension, gastro-oesophageal reflux disease, interstitial lung disease, acute upper respiratory tract infection, cervical spinal cord injury, heart-lung transplantation and cystic fibrosis [46]. Side-effects consisted mainly of transient throat irritation in a minority of subjects.…”

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“…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 122 . Capsicum annuum (red pepper) is a fruit spice of the Solanaceae family, rich in proteins, lipids, vitamins, carbohydrates, and health phytochemicals such as carotenoids, flavonoids and capsaicinoids known to prevent diseases such as asthma, coughs, sore throats etc.…”