Effect of e-Cigarette Use on Cough Reflex Sensitivity.
BACKGROUND
E-cigarettes (e-cigs) have attained widespread popularity, yet knowledge of their physiologic effects remains minimal. The aim of this study was to evaluate the effect of a single exposure to e-cig vapor on cough reflex sensitivity.


METHODS
Thirty healthy nonsmokers underwent cough reflex sensitivity measurement using capsaicin cough challenge at baseline, 15 min, and 24 h after e-cig exposure (30 puffs 30 s apart). The end point of cough challenge is the concentration of capsaicin inducing five or more coughs (C5). The number of coughs induced by each e-cig inhalation was counted. A subgroup of subjects (n = 8) subsequently underwent an identical protocol with a non-nicotine-containing e-cig.


RESULTS
Cough reflex sensitivity was significantly inhibited (C5 increased) 15 min after e-cig use (?0.29; 95% CI, ?0.43 to ?0.15; P < .0001); 24 h later, C5 returned to baseline (0.24; 95% CI, 0.10-0.38; P = .0002 vs post-15-min value). A subgroup of eight subjects demonstrating the largest degree of cough reflex inhibition had no suppression after exposure to a non-nicotine-containing e-cig (P = .0078 for comparison of ?C5 after nicotine vs non-nicotine device). Furthermore, more coughing was induced by the nicotine-containing vs non-nicotine-containing device (P = .0156).


CONCLUSIONS
A single session of e-cig use, approximating nicotine exposure of one tobacco cigarette, induces significant inhibition of cough reflex sensitivity. Exploratory analysis of a subgroup of subjects suggests that nicotine is responsible for this observation. Our data, consistent with previous studies of nicotine effect, suggest a dual action of nicotine: an immediate, peripheral protussive effect and a delayed central antitussive effect.


BACKGROUND
ClinicalTrials.gov; No.: NCT02203162; URL: www.clinicaltrials.gov.
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Montefiore Medical Center, Bronx, NY. Electronic address: pdicpin@gmail.com.
Peter V
PV
Dicpinigaitis
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Montefiore Medical Center, Bronx, NY.
Alfredo
A
Lee Chang
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Montefiore Medical Center, Bronx, NY.
Alis J
AJ
Dicpinigaitis
Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY.
Abdissa
A
Negassa
D000328:Adult; D002211:Capsaicin; D003371:Cough / Q000209:etiology* / Q000503:physiopathology*; D066300:Electronic Nicotine Delivery Systems / Q000009:adverse effects*; D005260:Female; D005731:Ganglionic Stimulants / Q000494:pharmacology*; D006801:Humans; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D012018:Reflex / Q000187:drug effects* / Q000502:physiology; D018689:Sensory System Agents
D005731:Ganglionic Stimulants; D018689:Sensory System Agents; D009538:Nicotine; D002211:Capsaicin
capsaicin; cough; electronic cigarette; nicotine