CIRCUMSTANCES MODIFYING THE ACTION OF DRUGS. 

 Mode of Administration. 



The following table gives the various methods of administering drugs 

 in order of their rapidity of absorption, beginning with the method by 

 which absorption is most rapid, and following with those by which ab- 

 sorption is less and finally least rapid: 



1. Intravenous, by injection into the veins. 



2. By inhalation (volatile drugs). 



3. Subcutaneous, or intramuscular, by injection into subcutaneous 



tissue, or deep into a muscle. 



4. Intratracheal, by injection into the trachea. 



5. Oral, by the mouth. 



6. Rectal, by the rectum. 



7. Inunction, by the skin. 



8. Intramammary injection. 



1. Injection into 'the veins (usually into the jugular) is not so com- 

 monly practiced as the subcutaneous method, as there is a certain minute 

 danger of inducing phlebitis, embolism and thrombosis. The danger is 

 more theoretical than real, however, as we have frequently thrown from 

 5§ (150 mils) to 6%§ (200 mils) of fluidextract of cannabis indica into 

 the jugular, and even chloral hydrate, a most irritating and caustic drug, 

 in the dose of 1§ (30 mils) dissolved in 8§ (240 mils) of water, without 

 producing any untoward symptoms. No method of administration can 

 secure more rapid absorption, since intravenous injection is absorption. 

 This has constituted one of the theoretical objections to the method, that 

 the sudden entrance of a drug might create shock. Injection into the 

 jugular is useful when very rapid and effective action ii imperative, as 

 in causing immediate catharsis in colic and intestinal obstruction of 

 horses. In such cases barium chloride and eserine sulphate are employed 

 intravenously. The jugular is occluded with the hand and the injection 

 is made with the same care described below in reference to the sub- 

 cutaneous method. The intravenous use of warm normal salt solution is 

 frequently valuable in hemorrhage, shock and poisoning (see p. 517). 



2. Volatile drugs are absorbed with great rapidity and effect owing 

 to the enormous vascular surface of the lungs in contact with the inhaled 

 vapor. Ether, chloroform, ammonia and amyl-nitrite are given by this 

 method. Inhalation of medicated steam and sprays, used mainly for their 

 local action on the respiratory tract, are also absorbed to some extent by 

 the bronchial mucous membrane and lungs. This is a convenient and 

 effective mode of applying local medication to horses in inflammatory 

 troubles of the upper air passages, including the bronchial tubes, and in 

 many cases may effect a cure without the use of internal remedies. 



3. Subcutaneous or hypodermatic injection is suitable for soluble, 

 non-irritating drugs of small bulk, when a sure and rapid action is de- 



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