• Exposure to a citric acid/capsaicin aerosol induces a cough which can be inhibited by codeine.


  • Chronic cough is a common symptom of respiratory diseases such as asthma, COPD and allergic rhinitis. Anti-tussive medications are amongst the most widely used drugs in the world and most have poor efficacy and/or side-effect profiles.


  • Guinea Pig, Rabbit


  • Citric Acid/Capsaicin

Dosing routes:

  • P.O., I.P., I.T. S.C., I.N. and I.V.

Study Duration:

  • Approximately 2 weeks

Parameter Measures:

  • Latency of cough onset
  • Frequency of coughs min-1
  • Total number of coughs
  • Plasma for PK analysis

Effect of codeine on citric acid-induced cough responses in the guinea pig

Cough - citic acid + codeine


Cough - citic acid + codeine (mean)

Effect of codeine on capsaicin-induced cough responses in the guinea pig

Cough - capsaicin + codeine

Cough - capsaicin + codeine (mean)