•954 



CONTROL OF BIOLOGICAL PRODUCTS 



Sample A contained more than a lo per cent excess of units. Sample B failed. 

 Sample C had the potency claimed but less than a 25 per cent excess. 



The excess for which tests were made should have been present to provide for a 

 maintenance of full, labeled potency up to the expiration date of the product. 



In addition to this method of standardization which gives results in terms of what 

 is usually spoken of as the "American" unit, the German unit established originally 

 by Behring is in use to a considerable extent. This unit is approximately sixty-six. 

 times the strength of the American unit — in other words, one German unit is the 

 equivalent of approximately sixty-six American units. 



Within recent months the Serums Committee of the Health Section of the League 

 of Nations has adopted an international unit which shall be precisely half the strength 

 of the American unit — in other words, two new international units will be the equiva- 

 lent of one American unit. It is too early to predict the extent to which this unit will 



come into use. 



TABLE IV 



BOTULINUM ANTITOXIN 



There are several immunological types of Clostridium botulinum, designated "A," 

 "B," and "C." The field of usefulness of the antitoxins corresponding to these toxins 

 is not well defined and is very limited. 



Bengtson^ has standardized these antitoxins, the method being outlined as fol- 

 lows: 



The unit of botulism antitoxin (type A) is a definite amount of the standard antitoxin; 

 for the standard antitoxin in the concentration used at present, and to be sent out to serum 

 estabhshments which may be licensed for the production of botulism antitoxin, the unit is 

 0.4 CO. of the glycerinated solution. The antitoxin to be tested is compared with the standard 

 unit by means of a test dose of toxin; this test dose of toxin is chosen so that when mixed 

 with one-tenth of a unit of the standard antitoxin and injected subcutaneously into a 250- 

 gram guinea pig, the guinea pig will die in about 96 hours. That amount of the unknown 

 antitoxin which when similarly mixed with the test dose of toxin and injected is just sufHcient 

 to protect a 250-gram guinea pig contains one-tenth of a unit. The test dose of toxin will 

 usually be found to contain from 50 to 200 minimal lethal doses. Before injection the doses 

 of toxin and antitoxin are to be thoroughly mixed, and then kept at room temperature for 



' Bengtson, I. A.: Hygienic Laboratory Bull. 136. 1924. 



