CAFFEINE 497 



CAFFEINE 



CAFFEINA. An alkaloid usually obtained from the dried 

 leaves of tea, Camellia thea, or the dried seeds of Coffea 

 arabica. C 8 H 10 N 4 2 , H 2 0. (B.P.) Nat. Ord. Tern- 

 stromiaceae or Rubiaceae. 



Caffeine and theine are now considered identical, and the 

 same alkaloid is also got from the seeds of the Guarana 

 or Paullinia Sorbilis, the leaves of Ilex paraguayensis, as 

 well as from the Kola nut. Caffeine (Trimethyl-xanthine) is 

 homologous with theobromine (Dimethyl-xanthine), which 

 is obtained from the nibs of the Theobroma cacao. Caffeine 

 occurs in colourless, inodorous, acicular crystals, soluble in 

 seventy parts cold water, in one of boiling water, seven of 

 chloroform, and in forty of alcohol. Treated with a crystal 

 of potassium chlorate, and a few drops of hydrochloric acid, 

 and the mixture evaporated to dryness in a porcelain dish, 

 a reddish residue results, which becomes purple when 

 moistened with ammonia. 



Caffeine citrate, obtained by adding caffeine to a hot 

 solution of citric acid, is a white, inodorous powder, with 

 an acid taste and reaction. It is soluble in thirty-two 

 parts of water, and in twenty-two of alcohol. 



ACTIONS AND USES. Cadeine stimulates and subsequently 

 paralyses the nerve-centres of the cerebrum, cord, and 

 medulla. In dogs, cats, rabbits, and rats, full doses, hypo- 

 dermically injected, do not, as in man, act prominently on 

 the brain, but chiefly affect the spinal cord, exalt reflex 

 excitability, and cause muscular rigidity, convulsions, and 

 tetanus (Phillips). Large doses swallowed by dogs, more- 

 over, sometimes cause vomiting, and gastro-intestinal 

 irritation. 



Like theobromine, it exerts a restorative effect on both 

 voluntary and involuntary muscles, by direct action on the 

 muscle fibres, enabling them to perform increased work. 

 On account of its stimulating the medulla and cardiac 

 centres, moderate doses increase respiration and pulse rate, 

 and raise blood-pressure ; and, resembling strychnine and 

 veratrine, caffeine antagonises heart and lung inability and 



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