INTKODUCTION 35 



hibition of peristalsis in the intestine resulted from the administration 

 of as little as 1 milligram. 



Parenteral Injections. In some instances, when fairly rapid but not 

 instantaneous results are desired, the gland extracts can be introduced into 

 the intramuscular or the subcutaneous tissue spaces. Absorption then takes 

 place into both the lymphatic and blood capillaries. The same is true 

 of extracts introduced into the peritoneal cavity. In this case the absorp- 

 tive function of the omentum is probably of considerable importance. Par- 

 enteral injections have certain advantages: the extracts are spared the 

 possibly deleterious action of the digestive enzymes of the alimentary 

 tract. There is less danger to the experimental animal as from throm- 

 bosis, and less disturbance of body functions than when intravenous in- 

 jections are employed. The possibility of infection and consequent abscess 

 formation is an obvious disadvantage which must be guarded against. In 

 case of epinephrin, at any rate, there is also the possibility of tissue necrosis 

 due, supposedly, to prolonged local ischemia. In case of intramuscular 

 injections the promptness of the appearance of the reaction is little less 

 than when the extracts are given by vein, but the relatively slower absorp- 

 tion is likely to result in quantitatively less marked, though more pro- 

 longed reactions. When dilute epinephrin is administered intramus- 

 cularly, the fact that it dilates the surrounding blood vessels probably 

 accounts to a considerable extent for the rapidity of its absorption. On a 

 priori considerations it might be desirable to incorporate the gland ma- 

 terial under investigation in relatively insoluble menstrua in order to 

 bring about a slow but prolonged absorption of the material, thus simulat- 

 ing its normal discharge from the glands. In a series of unpublished 

 experiments, the writer attempted some years ago to produce in this way 

 the equivalent of hyperepinephrinemia, but local tissue necrosis prevented 

 any conclusive results. 



Intrapulmonary Injections. That the intrapulmonary route is not 

 without advantages for the administration of epinephrin was reported by 

 Auer and Gates. The capillary circulation in the lungs is relatively 

 profuse and the drug is separated from the blood stream by only the 

 thin alveolar and capillary membranes. Absorption is correspondingly 

 prompt. The method would seem to be particularly well adapted to 

 getting epinephrin quickly to a failing heart. At the same time one danger 

 in the use of that substance in such cases would probably be obviated, 

 namely, the danger of inducing fibrillation of the ventricle, such as 

 may result when the injection is made directly into the heart. When 

 epinephrin is thus introduced it is likely to be carried in too great con- 

 centration to the coronary vessels or be deposited in the ventricular wall 

 itself, thus causing an overstimulation and the result mentioned. The 

 suitability of intrapulmonary injections as a method of administering 

 other hormones than epinephrin remains yet to be determined. Except 



