14 CIRCUMSTANCES MODIFYING THE ACTION OF DRUGS 



since superpurgation may occur. A high temperature alters 

 the action of many drugs. 



Opium is not so efficient as an analgesic in fevers, while 

 antipyretics will not lower the temperature in health. 

 Stimulants are not nearly so potent in depressed bodily 

 conditions, and counter-irritants will not produce their 

 characteristic actions on the skin when the circulatory 

 functions are at a low ebb. 



Idiosyncrasy. — Individual susceptibility to drugs is 

 infrequent, but unfortunately cannot be anticipated. The 

 writer has seen simple zinc oxide (free from adulteration or 

 impurities) cause a frenzy of irritation when rubbed on a 

 dog's skin, and a small dose of tartar emetic cause violent 

 vomiting in a cow. Some animals are very susceptible to 

 counter-irritants. Well-bred animals are commonly more 

 responsive to drugs than others. 



