ALLANTOIN AND UREA— ROBINSON 459 



bases and thoroughly mixed. It goes at once into sohition in the 

 water that is present. 



Despite the cheapness of urea and the ease with which it can be 

 made into a pharmaceutical product, it is still unpopular. At the 

 present time only four urea preparations are known to have been 

 made. 



Both allantoin and urea when undissolved are white in color and 

 crystalline in form. In solution they are colorless and odorless. 

 Allantoin, having no taste, is especially acceptable for treatment in 

 the mouth and is now being used extensively for that purpose. Suss- 

 man (1937) has recently published a series of case histories on the 

 successful use of allantoin in the treatment of resistant infections of 

 the mouth. Weak solutions of urea, from 1 to 2 percent, have only 

 a mildly unpleasant taste, not enough to make them unsuitable for 

 oral use, and such solutions are giving excellent results. In some 

 cases where the taste is objectionable a flavoring material is added. 



Neither allantoin nor dilute urea has any direct bactericidal prop- 

 erty; yet the bacterial count usually goes down in a purulent wound 

 when either of these materials is applied. They have no proteolytic 

 or dissolving action, but necrotic material in discharging wounds 

 begins to disappear and the woimd becomes cleaner under treatment. 

 Such effects, therefore, cannot be attributed to any direct activity 

 of these healing agents. It has been observed repeatedly, how^ever, 

 that they do stimulate growth of granulation tissue having an abun- 

 dant blood supply. The probability is, therefore, that the cleansing of 

 the wound is produced indirectly through the stimulation of an under- 

 lying growth of healthy granulation tissue. 



The fate of a new drug is typically uncertain. Sometimes its 

 merits are overemphasized and early reports of good results cannot be 

 duplicated. Not fulfilling expectations, it frequently falls into dis- 

 repute. It was this that led a professor of pharmacology to say to 

 his students: "Gentlemen, make haste to use a drug while it is new." 



The truth cannot be avoided that allantoin once fell by the wayside. 

 This was not because of disappointment in results but through neglect. 

 With its merits still untested except by Macalister and his associates, 

 it became forgotten. No use appears to have been made of its healing 

 powers in the World War which began 2 years later; and no mention 

 of it has been found in any works on pharmacology, therapeutics, or 

 pathology. Strangely enough, the reappearance of allantoin as a 

 therapeutic substance has been in strong contrast to its original dis- 

 covery. This time, being accompanied by an unusual amoimt of 

 publicity, the opportunity to test it thoroughly has been possible. 



Urea, however, is in a class by itself for large-scale treatments, 

 either civilian or military. Its cheapness, its availability in ton lots 

 if desired, the ease with which it goes into solution, its hannlessness 



