98 VASOCONSTRICTORS 



3. VASOCONSTRICTORS 



Vasoconstrictors are drugs which constrict the peripheral arte- 

 rioles. They may act by : 



1. Stimulating the vasomotor center (atropine, caffeine, strych- 

 nine). 



2. Stimulating the muscles of the arterial walls directly (adrena- 

 line). 



3. Acting both centrally and peripherally (digitalis, ergot, 

 cocaine). 



Vasoconstrictors raise blood pressure, tend to lessen the number 

 of the heart's beats by increasing the tonus in the medulla and 

 stimulate respiration. They are indicated internally in conditions of 

 low arterial tension, as collapse and shock. 



Vasodilators act directly opposite to the constrictors. The most 

 important members of this group are the nitrites and especially the 

 organic nitrites (nitroglycerin, erythrol, etc.). These act periph- 

 erally and are indicated when it is desired to lower arterial pres- 

 sure so as to facilitate the passage of blood through the vessels and in 

 this way lessen the work of the heart. 



EPINEPHRINA — EPINEPHRINE 



Synonyms. Adrenaline, Suprarenaline, Superacapsuline. 



This is an alkaloid obtained from the extract of the suprarenal 

 glands of animals used as food for man. This preparation is sold 

 under various trade names, adrenaline, supracapsuline, suprarena- 

 line, etc., in a solution supposed to be of the strength of one part of 

 adrenaline chloride to one thousand. This solution is not decom- 

 posed by a moment's boiling and consequently may be sterilized by 

 heat, but prolonged boiling decomposes it. On long standing, or 

 when diluted, it slowly deteriorates, changing to a pinkish color, and 

 finally forms a precipitate. It should be discarded upon the appear- 

 ance of a precipitate. There is a synthetic preparation, " supra- 

 renin," of about half the strength of the above. 



The dried glands are official as " Suprarenalum Siccum." 



Preparations and Doses. 



Solution of Adrenaline chloride 1 — 1000. 



Suhcutaneously. Horses and Cattle. 3j — ij ; 4 — 8. Dogs. 

 HI iij— viij ; 0.2—0.5. 



Intravenously. Dilute with ten parts of physiological salt 

 solution. Dose of the mixture : Horses and Cattle. 3ss 

 — ij; 2—8. Dogs. TTL ij— viij ; 0.13—0.5. 



In shock give intravenously in the proportion of 1 — 50,000 in 

 physiological salt solution. The injection should be made slowly and 

 as needed. 



