290 DRUGS ACTING UPON RESPIRATORY SYSTEM 



a deep inspiration followed by a forceful expiration with closed 

 glottis. The glottis opens and the air is expelled through the mouth. 

 It has a physiological function in the removal of irritant material 

 from the respiratory passages. It is evident that if these irritants 

 can be removed by coughing, no attempt should be made to check it. 

 On the other hand if these irritants cannot be removed in this man- 

 ner, or if the cough is excessive or persists long after its cause has 

 ceased to be active, it may do more harm than good. In either of 

 these cases some treatment is necessary. 



It is necessary to remember that cough is only a symptom, and 

 if treated as such, no permanent benefit can result unless it is di- 

 rected against the cause, if this is still active. The source of irri- 

 tation in the respiratory passages may be free in the lumen of the 

 bronchial tubes, may be in the mucous membrane of the larynx 

 or deeper channels of respiration, or in the lungs. 



Since cough is a reflex act it may be treated centrally or peripher- 

 ally. For the central treatment any drug may be used that de- 

 presses the respiratory center. Some of the preparations of opium 

 are the most useful and are preferred in the following order: 

 heroine, codeine, morphine and the crude drug. Chloroform and the 

 bromides are useful but are not so good as the others. 



The peripheral treatment is directed at the inflammation and 

 the attendant phenomena and must be modified according to the 

 seat of the inflammation. If accessible to local applications or 

 above the larynx, antiseptics may be applied as a douche or electuary. 

 If below the larynx inhalations of volatile antiseptics are indicated 

 (creolin, creosote, turpentine). These are applied in a manner 

 commonly called steaming. These agents are frequently given orally 

 to produce their effect when excreted by the bronchi and lungs, but 

 are of doubtful value. 



The irritation may be diminished by demulcents or anodynes. 

 Although these agents cannot be applied below the larynx, there 

 seems to be some favorable action in more distant irritation. These 

 demulcents (gummy agents) appear to act mechanically by protect- 

 ing the mucosa from air and bacteria, which are usually the cause of 

 the irritation, although some stimiilate the secretion of saliva and 

 tend in this manner to keep the parts moist (acacia, sugar, licorice). 



Local anodynes depress the sensory endings of the nerves in the 

 respiratory passages but are of no greater service in the relief of 

 cough than the central depressants and are applied with much more 

 diificulty. Cocaine, atropine or hydrocyanic acid may be used. Hy- 

 drocyanic acid is most frequently employed in the form of the ofii- 

 cial syrup of wild cherry. 



Next to the treatment of the cough comes the treatment for 

 changing the character of the secretions. The agents used for this 

 purpose are the expectorants which have been discussed previously. 



