DRUGS ACTING ON THE CIRCULATION 33 



(a) Drugs acting systemically to contract vessels. 



Pituitary extract Digitalis Strychnine 



Adrenalin Strophanthus Hamamelis 



Cocaine Squill Hydrastis 



Ergot Sparteine Physostigmine 

 Atropine 



(b) Drugs acting systemically to dilate vessels. 



Amyl nitrite Thyroid secretion 



Nitroglycerin Chloral 



Spirit of nitrous ether Aconite 



Alcohol Opium 



Salicylates Belladonna (secondary action) 



Ether Hyoscyamus (secondary action) 



Chloroform Stramonium (secondary action) 



(c) Agents acting locally to contract vessels. 



Secretion of the suprarenal and Cold 



pituitary glands Astringents 



(d) Agents acting locally to dilate vessels. 



Heat Thyroid secretion 



Counter-irritants 



Uses. — Drugs or agencies causing general dilatation of vessels are 

 useful in overcoming internal congestions and colds by equalizing the 

 circulation ; that is, by causing the blood to be distributed more uniformly 

 about the body. Some are also of benefit in morbid conditions attended 

 with a high, vascular tension; and are serviceable in dilating peripheral 

 vessels and in causing perspiration and loss of heat in fevers (spirit of 

 nitrous ether and salicylates). Drugs inducing general contraction of 

 vessels are employed in disorders characterized by loss of tone, as in 

 shock and collapse; and in heart weakness or disease (adrenalin, digitalis 

 and strychnine) ; also in internal hemorrhage and inflammations (ergot) ; 

 and to aid the absorption of dropsies and edemas. The uses of drugs 

 locally contracting vessels will be described under astringents (p. 53) 

 and of agents locally dilating vessels under counter-irritants (p. 52). 



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