ACTION OF DIGITOXIN 



40!) 



spiratory tambour) inject slowly and cautiously one-hall' 

 cubic centimeter of the drug. 



Caution: Digitoxin preparations on the market are exceedingly variable in 

 strength and composition. Each preparation must be tested before the size 

 of the dose for an animal can be determined. The object here is to give very 

 small doses and bring on the action of the drug very slowly. 



Fig. 330. Tracing showing the action of one milligram of digitoxin on the blood-pressure 



and respiration in a dog. Slow drum. 



Watch for any slight, changes in the amplitude of the 

 manometer tracing. The drug should first slow the heart 

 slightly. The pressure may be somewhat elevated during 

 this period which corresponds to the therapeutic (1st) 

 stage. As the action of the drug becomes more marked the 

 heart is greatly slowed (2nd stage) provided the inhibitory 

 apparatus is working normally. The center is stimulated 

 by the drug and this indirectly slows the heart by inhibition. 

 Give a few small injections slowly from time to time at first 



