'ACTION OF ACETANILID, ANTIPYEIN AND PHENACETIN 32l 



Blood. — These agents have no influence upon the Wood, 

 in moderate medicinal doses, but in large doses (except anti- 

 pyrin) they diminish the ozonizing power of the blood, re- 

 duce the haemoglobin of the red corpuscles, change it to 

 methasmoglobin, and alter the color of the blood to a brown- 

 ish-red hue. In large toxic quantities, administered continu- 

 ously, they cause disintegration of the red corpuscles and 

 elimination of the blood-coloring matter in the urine. 



Heart and Blood Vessels. — In ordinary therapeutic 

 doses these drugs do not alter the normal condition of the 

 heart or blood vessels, but in large medicinal doses they first 

 stimulate and then, slow and depress the force of the heart by 

 ' action (probably) upon the heart muscle. Phenacetin is the 

 least, and acetanilid the most depressant. Antipyrin is said 

 to stimulate the heart and increase blood pressure in minute 

 quantities. These three antipyretics decidedly diminish 

 blood tension in large medicinal doses, owing to depression 

 of the heart and of the vasomotor apparatus. 



Nervous System. — ^Usual therapeutic doses of these sub- 

 stances exert a sedative action upon the sensory nerves and 

 sensory tract of the spinal cord. They are therefore anal- 

 gesics, although not comparable in this respect to opium. 

 Poisonous quantities of these drugs diminish muscular 

 power, lessen reflex action and cause paralysis. Experi- 

 ments apparently show that acetanilid paralyzes the motor 

 nerves, antipyrin the motor nerve endings, while motor de- 

 pression seems to be of spinal origin in the case of phen- 

 acetin. The brain is undoubtedly influenced by these agents, 

 as evidenced by coma and convulsions in poisoning, but exact 

 knowledge is wanting in relation to the action upon the brain. 

 The functions of the cerebral cortex are thought to be de- 

 pressed by antipyrin, and the special sefases to be first stimu- 

 lated and then paralyzed by this drug. 



Temperature. — A'cetanilid, antipyrin and phenacetin are 

 essentially antipyretics. While they do not invariably lower 

 temperature, even in large doses in normal animals, they do 

 so very materially in animals suffering from fever. They 

 apparently depress the activity of the calorefacient centres 



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