USES OF DIURETICS 293 



properly there is diuresis, and the excess of water with certain dis- 

 solved materials is cast off. 



Hydremic plethora and its resultant diuresis may result from 

 the absorption of dropsical fluid under the administration of digitalis. 

 It may also be produced intentionally by the ingestion of water or 

 of solutions of dialyzable substances, so that these are diuretic. 



(4) Direct renal stimulants. Chief of this group are: 



Caffeine Calomel 



Theobromine Blue mass 



Theophylline Scoparius. 



Buchu, uva ursi, turpentine, copaiba, and cubeb also exert a 

 specific action on the renal epithelium, but are mostly used to 

 stimulate the mucosa of the genito-urinary tract and as urinary an- 

 tiseptics, very rarely as diuretics. They will be considered under 

 the head of stimulants to the genito-urinary tract. 



(5) Mechanical. These act by flushing out the renal tubules. 

 They include water, milk and organic acids. Their results are pro- 

 duced very much as that of the salines. They increase the amount 

 of fluid in the blood (plethoric hydremia), which raises blood pres- 

 sure, increases the rate of the blood flow and capillary transudation 

 especially in the kidneys. 



There is but little positive knowledge concerning the influence 

 of drugs upon the solids eliminated by the kidneys. The amount of 

 solids may be increased by consuming large amounts of water. This 

 has been shown as due to a flushing out of the waste products and 

 not to any increase in proteid metabolism. It is commonly believed 

 that the alkaline diuretics hasten oxidation in the tissues and con- 

 sequently nitrogenous elimination but such an action has not been 

 demonstrated. The investigations concerning this action have not 

 been very convincing. 



Digitalis, Strophanthus and Caffeine have no pronounced effect 

 upon the solids normally found in the urine, but caffeine occasionally 

 produces slight glycosuria. On the other hand, certain drugs which 

 have no activity as diuretics notably increase the amount of the solids 

 in the urine. For instance, salicylic acid increases the elimination 

 of urea, uric acid, and sulphur compounds. Colchicum probably in- 

 creases the amount of uric acid, and thyroid extract increases to a 

 great extent the elimination of nitrogen and the phosphates by in-, 

 creasing the destruction of proteids in the tissues. 



Uses of Diuretics. 



(1) To remove excrementitious matter from the hlood. They 

 are useful for this purpose when the secretory functions of the kid- 

 neys are impaired or suspended, as often in acute febrile diseases. 



