856 CHEMOTHERAPY 



8. Salvarsan and its congeners may vary, within certain limits, in 

 therapeutic effect, and to a greater degree in toxicity. The ampules 

 obtainable in the open market exhibit striking variations in toxicity. 



9. Even the poorest compounds, however, are tolerated by animals 

 in much higher amounts than the maximum dose administered to man, 

 so that there is nearly always a latitude of safety. 



10. Salvarsan is a safer substance than mercury, and can be tolerated 

 intravenously by white rats in fifty times the dose of the latter, weight 

 for weight. 



Properties of Neosalvarsan. This is an orange-yellow powder 

 possessing a peculiar odor. It is very unstable in the air and is readily 

 soluble in water, yielding a yellow solution that is neutral to litmus. Its 

 structure is somewhat more complex than that of Salvarsan, being a 

 condensation-product of the latter and hydraldit (formaldehyd sulph- 

 oxylate of sodium), the reaction taking place according to the follow- 

 ing equation: 



As As As 



^ S\ 



NH 2 ! = NH 2 + HO.CH.O.SO Na = NH 2 



OH 



OH 



As 



rv 



NH.CH 2 O.SO Na+H 2 O 



OH 



While neosalvarsan is less toxic than salvarsan, and although it is 

 much more easily administered and largely free from irritative effects, 

 recent clinical reports would tend to show that its spirocheticidal prop- 

 erties are somewhat less than those of salvarsan. 



Sodium Salvarsan (Salvarsannatrium). Ehrlich has recently per- 

 fected a sodium salt of salvarsan which may be called a "neutralized 

 salvarsan," a product regarded as possessing the curative value of sal- 

 varsan and the lower toxicity and ease of administration of neosal- 

 varsan. The reports of Wechselman, 1 Dreyfus, 2 Loeb, 3 Fabry and 

 Fischer, 4 and Gutman 5 regarding the therapeutic value of the new 



1 Munch, med. Wchnschr., 1915, Ixii, 177. 



2 Munch, med. Wchnschr., 1915, Ixii, 178. 



3 Deutsch. med. Wchnschr., 1915, xli, 338. 



4 Munch, med. Wchnschr., 1915, Ixii, 612. 



5 Berl. klin. Wchnschr., 1915, lii, No. 16. 



