Methodology to evaluate the efficacy of
antitussive drugs rely largely on subjective methods and
cough counts. There are few studies in
cough due to natural disease especially using objective techniques. This paper presents data from a series of randomized, double blind, placebo controlled clinical trials in
cough due to both chronic bronchopulmonary disease and acute
upper respiratory tract infections. In these studies,
cough was quantified using a standardized and validated computerized system for the acquisition and multidimensional analysis of the
cough sound. Key objective parameters like
cough counts, intensity, latency and total effort expended were studied.
Guaiphenesin and
bromhexine showed significant
expectorant effects in patients with productive
cough due to chronic bronchopulmonary disease. Differences were observed in speed of action, and objective and subjective measures, that probably indicate differences in
drug action. More recently, three studies evaluated the
antitussive drug dextromethorphan in non-productive
cough due to uncomplicated
upper respiratory tract infections. Reproducible
cough suppressant effects were demonstrated after a single 30 mg dose using objective measures of
cough counts, latency and total effort. These results establish the sensitivity and robustness of the
cough quantitation methodology in the objective evaluation of
cough treatments.