58 



Scientific Proceedings (125) 



The minimum sterilizing dose gives similar results. The 



maximum tolerated dose 

 therapeutic index , of gelatin- 

 minimum sterilizing dose 



arsphenamine is 1.4 times that of arsphenamine and corresponds 

 in this regard to Kolmer's findings with neo-arsphenamine. 

 Gram for gram, gelatin-arsphenamine is almost twice as ef- 

 fective as neo-arsphenamine. 



These relations may be summarized as follows : Gelatin- 

 arsphenamine is as effective as arsphenamine and 5/7 as toxic. 

 It is 1.9 times as toxic as neo-arsphenamine, arsphenamine being 

 2.4 times, and twice as effective. 



As used above "toxicity" refers to the late chemical toxicity 

 of the drug. An even more striking contrast is shown if the 

 immediate physical toxicity of arsphenamine and gelatin- 

 arsphenamine is considered. Considerable evidence has been 

 advanced indicating that the "reactions" occurring during or 

 soon after the injection of arsphenamine are due to this physical 

 toxicity 6 7 . Practically speaking, gelatin-arsphenamine has no 

 immediate toxicity. The immediate toxicity of arsphenamine 

 varies with the condition of the individual. For these reasons 

 no exact ratios can be established, but it can be stated that where- 

 as on account of its physical toxicity, a resulting "acute reaction" 

 is always a possibility during the injection of arsphenamine, it 

 seems unlikely from the experimental evidence on hand that such 

 acute mishaps could occur with gelatin-arsphenamine under any 

 conditions or with any dosage. 



MINIMUM EFFECTIVE DOSE 



Arsphenamine and Neo- Arsphenamine — Voegtlin 



M.L. D. (206) 



Thcraip. Index Arsphen. — 20 l . 



M. E. D. (9.9) 



M.L. D. (438) 



Therap. Index Neo-Arsph. = 24 1 . 



M. E. D. (20.6) 



Therap. Index Neo- Arsphen. 



Ratio = 1.2. 



Therap. Index Arsphen. 



c Karsner and B&nzlick, Jour. Pharm. and Exp. Therap., 1920, xiv, 479. 

 i Oliver and Yamada, Jour. Pharm. and Exp. Therap., 1922, xix, 393. 



