THE ELIMINATION OF CAFFEIN. 



AN EXPERIMENTAL STUDY ON HERBIVORA AND CARNIVORA. 



INTRODUCTION. 



As pointed out in a previous report (16), 1 the action of caffein has 

 been extensively studied during the past eighty years. Not until the 

 last decade of the nineteenth century, however, has its fate in the 

 body been made the subject of serious investigation. The appear- 

 ance in the nineties of the work of Albanese (1), of Bondzynski and 

 Gottlieb (3) , and of Kriiger and Schmidt (7) , in which the character 

 of the decomposition products of caffein and of theobromin was 

 established for the first time, marks, therefore, the beginning of 

 accurate information on the metabolism of caffein. These investi- 

 gations, however, concerned themselves mainly with the transforma- 

 tion products of caffein and allied substances, while the extent to 

 which it was eliminated unchanged received but little attention. The 

 study of the elimination of caffein was not altogether neglected, how- 

 ever. As shown in the following section, a number of attempts have 

 been made to investigate this problem. 



HISTORICAL REVIEW OF THE LITERATURE. 



An examination of the literature on caffein showed that the earliest 

 studies were those published by Lehmann (9), who reported nega- 

 tive results. According to Hammersten (6), caffein is found in the 

 urine after drinking tea or coffee as well as after the ingestion of 

 pure caffein. His conclusions were based on the presence of crys- 

 tals which he extracted from the urine and on the murexid test. 

 Draggendorff (5) examined the urine of individuals after drinking 

 tea and coffee, but was unable to find caffein. Aubert (2) analyzed 

 the urines of individuals who had taken caffein by mouth, and claimed 

 to have obtained positive results with the chlorin test. 



Experimental studies on animals were made for the first time by 

 Strauch (1 4) . According to his observations caffein was present in the 

 urine and bile of cats, dogs, rabbits, and guinea pigs after its adminis- 

 tration by mouth in doses of 0.25 to 0.5 gram. He examined the urine 

 at various intervals and stated that he found the alkaloid in some 

 cases two hours after it was given. For the separation of caffein the 

 urine was made alkaline with ammonium hydroxid and extracted 



1 Numbers in parenthesis refer to Bibliography, on p. 23. 



