The Treatment of Cough (7)(2) In evaluating antitussive action, it is not only important to assess a change in the frequency of cough, but also a change in intensity (severity). (3) Since objective cough counting can only evaluate cough frequency, while the patients subjective assessment probably integrates both cough frequency and intensity, it is possible for a drug to be considered effective when subjective and objective results deviate. On the basis of these conclusions, we decided to evaluate the literature on antitussive therapy according to the following guidelines: nonspecific antitussives can only be considered clinically useful if they have been shown to decrease significantly cough frequency or intensity (or both) by objective cough counting or standardized questionnaires in randomized, double-blind placebo-controlled studies in patients with pathologic cough. With few exceptions, only those drugs that have been adequately evaluated according to these guidelines will be mentioned in this review. Cheap Diskus Advair
Nonspecific antitussive drugs can be classified according to how and where they might theoretically control the cough reflex, as shown in the following classification:
1.    Alter mucociliary factors irritating cough receptors.
2.    Increase the threshold or latency (or both) of the afferent limb.
3.    Increase the threshold or latency (or both) of the cough center.
4.    Increase the threshold or latency (or both) of the efferent limb.
5.    Decrease the strength of contraction of the respiratory skeletal muscles.