62 GENERAL ACTIONS OF DRUGS 



fever is a natural protective agency, being tte result of 

 increased oxidation, and destroys toxins and pyrogenic sub- 

 stances. Acetanilid, antipyrin and phenacetin, moreover, 

 depress the circulation in large doses and alter the red 

 corpuscles so as to interfere with their oxygen-carrying 

 functions. Cold is the best antipyretic agency when it 

 can be employed, in not only reducing temperature and in- 

 creasing the elimination of toxins in the urine, but in 

 powerfully stimulating the nervous system and vital func- 

 tions. (See p. 704.) 



Drugs Acting on the Skin. 



(A) Drugs Influencing the Blood Vessels of the Skin. 

 (1) Locally dilating superficial vessels. 



IRRITANTS OR COUNTER-IRRITANTS. 



Cantharides Corrosive mercuric chloride 



Iodine Arsenous acid 



Mustard Silver nitrate 



Capsicum Zinc chloride 



Croton oil ' Carbolic acid 



Oil of turpentine and other Mineral acids 



volatile oils Caustic alkalies 



Ammonia water Anaesthetics and alcohol(when eva- 

 Camphor poration is prevented) 



Red mercuric iodide (Heat) 



Drugs are classified as follows, according to the degree 

 of irritation they province : 



Buhefacients are drugs which cause vascular dilatation 

 and redness of the skiu when locally applied, such as mus- 

 tard and iodine (and heat). 



Vesicants are drugs producing inflammation of the skin 

 and exudation of serum under the epidermis (vesicles), 

 when locally applied, such as cantharides. 



Pustulants are drugs inducing a still higher grade of 

 inflammation when locally applied, accompanied by migra- 

 tion of leucocytes from the vessels iuto the vesicles, forming 

 pustules. 



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