title: Omeprazole reduces the response to capsaicin but not to methacholine in asthmatic patients with proximal reflux.
abstract: OBJECTIVE
  To study the relationships between airway responsiveness to methacholine and capsaicin, proximal or distal reflux and the effects of short-term acid inhibition.
  
  
  METHODS
  Twenty-nine asthmatics, not taking steroids regularly, underwent respiratory symptom measurements, 24-h dual-probe pH monitoring, and challenges with methacholine and capsaicin. Challenges and symptom measurements were repeated after 12 days' omeprazole treatment (20 mg b.i.d.). The results (median and range) were expressed as PD20 methacholine (mg) and PD5 capsaicin (dose causing five coughs, nmol).
  
  
  RESULTS
  Seventeen patients presented pathological reflux in the distal esophagus, and 17 in the proximal esophagus. At baseline no correlation was found between PD20 or PD5 and reflux. Treatment with omeprazole did not change bronchial responsiveness to methacholine (basal: 0.16 mg, 0.02-1.27; omeprazole: 0.15 mg, 0.02-1.60); omeprazole decreased the tussive response to capsaicin (basal: 0.08 nmol, 0.08-2.46; omeprazole: 0.61 nmol, 0.08-9.84, p<0.001) only in patients with pathological reflux. The decrease was positively correlated with proximal acid exposure (r2=0.70, p<0.001). Omeprazole reduced asthma symptoms in patients with proximal reflux, cough in those with proximal or distal reflux.
  
  
  CONCLUSIONS
  In asthmatics, inhibition of gastric acid secretion does not influence bronchial hyperresponsiveness but decreases tussive sensitivity and this effect is related to proximal reflux.
authors.affiliation: Dipartimento di Scienze Biomediche e Chirurgiche, Università di Verona, Italy. marcello.ferrari@univr.it
authors.forename: Marcello
authors.initials: M
authors.lastname: Ferrari
authors.forename: Luigi
authors.initials: L
authors.lastname: Benini
authors.forename: Emanuele
authors.initials: E
authors.lastname: Brotto
authors.forename: Francesca
authors.initials: F
authors.lastname: Locatelli
authors.forename: Fosca
authors.initials: F
authors.lastname: De Iorio
authors.forename: Francesco
authors.initials: F
authors.lastname: Bonella
authors.forename: Naika
authors.initials: N
authors.lastname: Tacchella
authors.forename: Giuliano
authors.initials: G
authors.lastname: Corradini
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Lo Cascio
authors.forename: Italo
authors.initials: I
authors.lastname: Vantini
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D018712:Analgesics, Non-Narcotic; D000897:Anti-Ulcer Agents / Q000627:therapeutic use*; D001249:Asthma / Q000209:etiology / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000209:etiology / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects; D016085:Bronchoconstrictor Agents; D002211:Capsaicin; D050782:Esophageal pH Monitoring; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D005764:Gastroesophageal Reflux / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D009853:Omeprazole / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D018712:Analgesics, Non-Narcotic; D000897:Anti-Ulcer Agents; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D009853:Omeprazole; D002211:Capsaicin