90 CIRCULATORY DEPRESSANTS 



diminishing the resistance in the blood vessels. The general indica- 

 tions will be mentioned later. Page 105. 



Strychnine. This drug raises blood pressure by stimulating 

 the vasomotor center. This action combined with its influence upon 

 respiration, digestion and muscle tone make it a valuable remedy 

 in circulatory shock. In simple dilatation of the heart it can be 

 advantageously combined with digitalis. It may prove of more value 

 in pneumonia and other infectious diseases .than digitalis. It is also 

 indicated in chronic bronchitis and emphysema to support the res- 

 pirations as well as the circulation. Page 129. 



Barium. Barium chloride in small doses stimulates the heart 

 muscle and makes the heart beat stronger but more slowly. It there- 

 fore has a digitalis like action but is not used in therapeutics for that 

 purpose. 



Ammonium Compounds. Ammonia water, carbonate of am- 

 monium or the aromatic spirits of ammonia are quickly acting dif- 

 fusible stimulants in cardiac or respiratory failure. They may be 

 given per os and produce their action almost immediately, probably 

 through a reflex action by irritation of the stomach. They may also 

 be given by inhalation, in which case the action is due to irritation 

 of the fifth cranial nerve or in extreme cases may be given sub- 

 cutaneously or intravenously, Cushny says that in this case " the 

 local action may be reinforced by a direct action on the medulla 

 oblongata." The action is very transitory but may be sufficient to 

 tide the patient over a period of collapse. 



Alcohol. Strong alcoholic solutions are reflex circulatory stimu- 

 lants through irritation of the stomach. Their action is of but 

 short duration. 



Cactus Grandiflorus. There are several species of cactus with 

 more or less medicinal power, but the one mentioned above is 

 believed to be the most active so far as the circulatory system is con- 

 cerned. While some investigators claim that it is a distinct circu- 

 latory stimulant, others assert that it has very little action. At best it 

 must be considered very much in doubt. Cactoid Ahhoit. H. Gr. 

 yi2. D. Gr.i/eo. 



Liquor Hypophysis. Solution of pituitary body has an action 

 similar to that of adrenaline. It is discussed more fully under the 

 vasoconstrictors. 



2. CIRCULATORY DEPRESSANTS 



Circulatory depressants are agents that lessen the efficiency of the 

 heart and lower blood pressure. They may also be defined as those 

 agents which lessen the activity of the heart. They diminish the out- 

 put of the heart per unit of time and may produce this action by : 



1. Directly depressing the cardiac muscle (chloral hydrate, chloro- 

 form and potassium salts). 



