358 ALKALIES AND ALKALINE EARTHS 



Dose. H. 3ij — iv; 8. — 15. Intravenously, gr. vij — xv; 0.5 

 —1. 



Action and Uses. Barinm is a strong irritant, having a spe- 

 cial affinity for all forms of muscle. As soon as a muscle comes 

 into contact with barium it goes into tonic contraction. When taken 

 per OS it causes colicky pains, nausea, vomiting and increases peri- 

 stalsis due to the action of the drug upon the muscle of the intestines. 

 Death is caused by central nervous paralysis and is preceded by 

 strong tonic and clonic convulsions. Sodium sulphate is said to be 

 the best antidote. 



Muscle. Barium has an action on voluntary muscle like that 

 of veratrine. Plain muscle generally goes into contraction. The 

 muscle of the intestines contracts in rings or bands which relax 



Fig. 21. 

 Blood pressure tracing. Horse. Normal pressure tracing at the left. Effect 

 of Barium Ciiloride at the riglit. The vertical line above the tracing indi- 

 cates the point at whicli the injection was made. (Tracing made by Dr. 

 P. A. Fish.) 



slowly and are followed by others. Other plain muscles also con- 

 tract. The bloodvessels are constricted causing a great and per- 

 sistent increase in blood pressure. Cardiac muscle is aifected in the 

 same manner as other muscle. Barium resembles the action of a 

 digitalis on the heart but differs from digitalis in increasing the 

 rate. 



Therapeutics. The only indication for the use of barium is as 

 a purgative for the horse. See purgatives, p. 257. Its digitalis- 

 like action or action on the heart cannot be utilized on account 

 of its dangerous side actions. Barium should not be administered 

 aubcutaneously because it will cause abscess at the site of injection. 



