CAFFEIN. 



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feeble base. Tea contains 1 to 4 per cent, of caffein ; coffee, 

 0-2 to 0-8 : mate, 1-2 ; guarana, 5 per cent. It is closely allied 

 to theobromin, C 7 H 6 N 4 2 , being, in fact, methyl-theobromin, 

 C7H 9 (CH 3 )N 4 02, which can be made synthetically. 



Incompatible*. Tannic acid, iodide of potassium, and salts 

 of mercury. 



Dose. 1 to 5 gr., or more. 



Preparation. 

 Citrate of Caffein, in white needles. Dose, 1 to 5 gr. 



ACTION AND USES. 

 1. IMMEDIATE LOCAL ACTION AND USES. 



Coffee stimulates most of the digestive glands, being sialn- 

 gogue, stomachic and slightly laxative. So far it is diete- 

 tically wholesome. 



2. ACTION IN THE BLOOD, AND SPECIFIC ACTION AND USES. 



Caffein is absorbed into the circulation unchanged; and 

 acts chiefly upon the central nervous system. The cerebrum 

 is first stimulated, causing the clearness of intellect, the re- 

 moval of languor, and the sleeplessness, familiar after a cup of 

 strong coffee. Larger doses cause a species of narcotism ; but 

 there are great differences in this and other respects according 

 to the individual and other circumstances. In the 1< > \\-IT 

 animals the spinal centres are simultaneously affected to such ;i 

 degree that tetanic convulsions may occur, not unliko tlms-. 

 C;MISC<I by strychnia; but in man these effects on the lower 

 centres are quite subsidiary. The sensory and motor peri- 

 pheral nerves are not certainly affected. The muscle curve 

 is altered in character, and muscular contraction seems more 

 easily executed. The heart is first accelerated another 

 familiar effect of a full cup of coffee ; it is then slowed 

 and weakened. The blood pressure first rises and then falls. 

 Respiration is temporarily increased, then depressed ; an : 

 occurs in this way. Metabolism is probably somewhat in- 

 creased, and the temperature raised. In all these respects 

 habit markedly reduces the influence of coffee. 



Coffee and caffein may be used as a nervine stimulant and 

 restorative in ordinary conditions of fatigue. .M 

 qucntly relieved by either. Large doses must be avoided. 



3. REMOTE LOCAL ACTION AND USES. 



Caffein is excreted unchanged in the bile and urino, thr 

 latter presenting the characteristic odour of th' 



