CAFFEINE 293 



times cause thrombus and lameness in horses months afterwards owing 

 to its insolubility in the blood (Vet. Review, Dec, 1913). 



CAFFEHfA. Caffeine. C.H.oO.N.+HjO. (U. S. & B. P.) 



Synonym. — Theine, guaranine, E.; coffein, G. ; cafSine, Fr. 



A feebly basic substance, obtained from the leaves of Thea sinensis LinnS 

 (Fam. TernstroemiaceBe) , or from the seeds of Coffea arabica Linu6 (Fam. 

 Rubiacese), and found also in other plants; or prepared synthetically. 



Habitat. — Indigenous to Africa, and cultivated in other tropical countries. 



Derivation. — Crushed coffee is treated with successive portions of boiled 

 water, and the resulting solution is precipitated with lead acetate and filtered. 

 Hydrogen sulphide decomposes the excess of lead acetate rjemaining in the fil- 

 trate. The latter is then concentrated by evaporation and neutralized with 

 ammonia water. Caffeine crystallizes on cooling. The alkaloid is purified by 

 charcoal and recrystallization. 



Properties. — White, flexible, silky, glistening needles, usually matted together 

 in fleecy masses; odorless and having a bitter taste; efflorescent in dry air. Solu- 

 ble in 46 parts of water, 66 parts of alcohol, 530 parts of ether, and 5.5 parts 

 of chloroform at 25° C. Its solubility in water is increased by the presence of 

 certain salts, — e.g., potassium bromide, sodium benzoate, sodium salicylate, and 

 others. Caffeine is neutral to litmus paper. Caffeine exists, curiously enough, 

 as the active principle of the national non-alcoholic beverages in use all over 

 the world. Coffee contains .6 to 2.2 per cent, of caffeine, together with glucose, 

 fat, vegetable casein, tannic acid, and an empyreumatic oil developed by roasting, 

 i.e. caffeone. Tea contains 1.36 to 3. per cent of caffeine, or theine, and also a 

 volatile oil and tannic acid. Guarana (the seeds of PauUinia cupana) contains 

 4 to 5 per cent, of caffeine; mate, or Paraguay tea (the leaves of Ilex paraguay- 

 ^ ensis), contains .45 to 1.2 per cent. Caffeinq is found in kola nut (the fruit of 

 Sterculia acuminata), used as a beverage in Africa, and now as a nervous stimu- 

 lant in human medicine, and is allied to theobromine, occurring in chocolate 

 beans, and to cocaine, existing in coca leaves. 



Incompatibility. — Caffeine is incompatible with mercury salts, potassium 

 iodide and tannic acid. 



Dose.—H. & C, 3ss-ii, (2-8) ; D., gr.ss-ii, (.03-.2) ; H., gr.xxx, subcut. 

 Caffeina CiTRATA. Citratcd Caffeine. (U. S. P.) 



Derivation. — ^Dissolve citric acid (50) in hot, distilled water (100) ; add caf- 

 feine (60) and evaporate the resulting solution to dryness, on a water bath, con- 

 stantly stirring towards the end of the operation. Reduce the product to a fine 

 powder and transfer it to well-closed containers. 



Properties. — A white powder, odorless, having a slightly bitter, acid taste and 

 an acid reaction. Citrated caffeine gives a clear, syrupy solution with a small 

 quantity of water but caffeine precipitates on dilution. This precipitate redis- 

 solves on the further addition of water. 



Dose.—H. & C, 3ii-iv, (8-15); D., gr.i-vi, (.06-.36). 

 Caffeine Sodio-Benzoas. Caffeine Sodio-Benzoate. CsHmO^Nj, NaC^HsOj. 

 (U. S. P.) (Contains 46 to 50 per cent, of anhydrous caffeine.) 



A mixture of caffeine and sodium benzoate. White powder, odorless, and 

 has a slightly bitter taste. Soluble in 11 parts of water, in 30 of alcohol, and 

 partly soluble in chloroform. 



Dose. — Twice that of caffeine. H., 3i-ii, (4-8); D., gr.i-vi, (0.06-0.3), sub. 

 cutaneously. 



Action Internal. — Caffeine has no particular action upon the diges- 

 tive tract, except in large quantities, when it may cause gastro-intestinal 

 irritation. The effect of caffeine and raw coffee is identical, but when 

 the latter is roasted, aromatic oils, or an empyreumatic oil, are developed 

 (caffeone). It is impossible to separate completely the action of caffeine 

 from caffeone in boiled coffee. Recent investigations appear to show that 



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