Olodaterol attenuates citric acid-induced cough in naïve and ovalbumin-sensitized and challenged guinea pigs

PLoS One. 2015 Mar 17;10(3):e0119953. doi: 10.1371/journal.pone.0119953. eCollection 2015.

Abstract

Excessive coughing is a common feature of airway diseases. Different G-protein coupled receptors, including β2-adrenergic receptors (β2-AR), have been implicated in the molecular mechanisms underlying the cough reflex. However, the potential antitussive property of β2-AR agonists in patients with respiratory disease is a matter of ongoing debate. The aim of our study was to test the efficacy of the long-acting β2-AR agonist olodaterol with regard to its antitussive property in a pre-clinical model of citric acid-induced cough in guinea pigs and to compare the results to different clinically relevant β2-AR agonists. In our study β2-AR agonists were intratracheally administered, as dry powder, into the lungs of naïve or ovalbumin-sensitized guinea pigs 15 minutes prior to induction of cough by exposure to citric acid. Cough events were counted over 15 minutes during the citric acid exposure. Olodaterol dose-dependently inhibited the number of cough events in naïve and even more potently and with a greater maximal efficacy in ovalbumin-sensitized guinea pigs (p < 0.01). Formoterol and salmeterol showed a trend towards reducing cough. On the contrary, indacaterol demonstrated pro-tussive properties as it significantly increased the number of coughs, both in naïve and ovalbumin-sensitized animals (p < 0.001). In conclusion, olodaterol, at doses eliciting bronchodilation, showed antitussive properties in a model of citric acid-induced cough in naïve and ovalbumin-sensitized guinea pigs. This is in agreement with pre-clinical and clinical studies showing antitussive efficacy of β2-AR agonists. Indacaterol increased the number of coughs in this model, which concurs with clinical data where a transient cough has been observed after indacaterol inhalation. While the antitussive properties of β2-AR agonists can be explained by their ability to lead to the cAMP-induced hyperpolarization of the neuron membrane thereby inhibiting sensory nerve activation and the cough reflex, the mechanism underlying the pro-tussive property of indacaterol is not known.

MeSH terms

  • Adrenergic beta-2 Receptor Agonists / administration & dosage
  • Adrenergic beta-2 Receptor Agonists / therapeutic use*
  • Animals
  • Antitussive Agents / administration & dosage
  • Antitussive Agents / therapeutic use*
  • Benzoxazines / administration & dosage
  • Benzoxazines / therapeutic use*
  • Citric Acid
  • Cough / chemically induced
  • Cough / drug therapy*
  • Drug Evaluation, Preclinical
  • Guinea Pigs
  • Male

Substances

  • Adrenergic beta-2 Receptor Agonists
  • Antitussive Agents
  • Benzoxazines
  • Citric Acid
  • olodaterol

Grants and funding

This study was funded by Boehringer Ingelheim Pharma GmbH & Co. KG. The funder provided support in the form of salaries for authors EW and TB, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the "author contributions" section.