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J Pharmacol Toxicol Methods. 2010 Mar-Apr;61(2):157-62. doi: 10.1016/j.vascn.2010.02.015. Epub 2010 Mar 1.

Use of within-group designs to test anti-tussive drugs in conscious guinea-pigs.

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Sackler Institute of Pulmonary Pharmacology, Pharmaceutical Science Division, School of Biomedical and Health Science, Kings College London, London SE1 1UL, United Kingdom.



Cough is a common medical problem for which there are few effective drug treatments. A limited understanding of the mechanisms of induction and maintenance of cough and a paucity of suitable animal models frustrate drug discovery efforts to find novel anti-tussives. As in humans, guinea-pigs evoke a cough reflex upon exposure to tussive agents such as citric acid and capsaicin; both of which have been widely used to assess novel anti-tussive drugs. However, the potential for using within-group designs in drug development has received little attention and such designs may offer a way of assisting the drug discovery effort in the area of cough as well as other areas.


Cough can be monitored in conscious guinea-pigs by placing animals in a Perspex chamber, in which air is continually exchanged by use of negative pressure and drug delivery of aerosols to the chamber can be accurately timed. Cough in response to a tussive agent (e.g. 0.2-0.4M citric acid; 10-30 microM capsaicin) is detected by the simultaneous microphonic recording of audible signals characteristic of the cough response as well as by positive pressure changes in the chamber generated by a cough dependent rapid expiration of air from the lungs. Both the sound and pressure signals are recorded using an online analyzer, whilst the number of coughs can be analyzed off-line. The number of coughs over a 15 min period is used to quantitate tussive events.


Reproducible cough can be detected in animals using cross-over designs that lend themselves to drug studies. Both the time and concentration dependence of anti-tussive drug action can be evaluated in the same animal. Furthermore, the effect of different anti-tussive drugs can be evaluated thereby reducing between group error and thereby improving the sensitivity of the test.


Repeated measures design improves the precision with which to evaluate anti-tussive drugs in preclinical models and could be used to make the drug discovery process more efficient.

[Indexed for MEDLINE]

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