952 



CONTROL OF BIOLOGICAL PRODUCTS 



The protocol shown in Table II illustrates tests on commercial antitoxins. 



It is customary to test commercial samples for the exact unitage claimed on the 

 label and for excess potency depending upon the length of time before the date of ex- 

 piration, hence the fractions above i unit in the preceding table. Sample A had the 

 unitage claimed, but less than lo per cent excess. Sample B had the unitage claimed, 



TABLE I 



Tests to Determine the L+ Dose of Toxin No. 74* 



I immunity unit-f-o.ig-cc. toxin. 

 I immunity unit-H .20-cc. toxin. 

 1 immunity unit-|- .21-cc. toxin 

 1 immunity unit+o.22-cc. toxin 



Invariably causes late paralysis, 

 never acute death 



Sometimes causes late paralysis 

 and sometimes acute death 



Always causes acute death about 

 the fourth day 



Alwaj's causes acute death, usual- 

 ly on the second or third day 



* The L_|_ dose of this toxin is, therefore, just 0.21 cc. 



but less than 30 per cent excess. Sample C was deficient for the unitage claimed, and 

 of course for the excess tested for — 5 per cent. The animals on the standard (control) 

 died at the correct time. 



Ramon's flocculation method.' — Ramon's method of testing the potency of diph- 

 theria antitoxin which eliminates the need for using laboratory animals is employed 



TABLE II 



Antitoxin Specimen 



A 



B 



C 



Standard antitoxin 

 Standard antitoxin 

 Standard antitoxin 



Weight of 

 Guinea Pig 



260 

 250 



260 

 250 



270 

 250 



260 



250 



380 



Tested For 



Unit 



1-3 



i-os 



Dose of Toxin 



(L+) 



o. 16^ 

 .165 



.165 

 .165 



.165 

 .165 



.165 



.165 



o. 165 



Result 



Dead 7 days, 22 hr. 

 Dead 2 days, 19 hr. 



Discharged 17th day 

 Dead i day, 18 hr. 



Dead 2 days, 9 hr. 

 Dead 2 days, 9 hr. 



Dead 4 days, 20 hr. 



Dead 4 days 



Dead 3 days, 14 hr. 



to a considerable extent. In some laboratories abroad the method is used for final as 

 well as for preliminary titrations of the serum, but in this country it is employed al- 

 most exclusively for the less exacting requirements, such as testing the serum of in- 

 dividual producing animals. 



Bayne-Jones'' considers that results obtained by Ramon's method agree within 3 

 per cent of those secured by titrations on animals. The procedure requires lirst the ti- 



■ See chap. Ivi of this volume. = Bayne-Jones, Stanhope: J. Inniiiniol., 9, 481. 1924. 



