In the preceding article,1 we have summarized the histologic changes found in certain organs of rats and rabbits at varying intervals after the intravenous injection of solutions of arsphenamin in single large and multiple therapeutic doses. The purpose of the present article is to record the results of a similar study with solutions of neo-arsphenamin.
This study has proved of much interest not only in relation to the subject of chemotherapy with arsenic compounds, but particularly by reason of its bearing on the choice of arsphenamin or neo-arsphenamin for the treatment of syphilis. As shown by Schamberg, Kolmer and Raiziss,2 neo-arsphenamin injected intravenously is generally borne by white rats in a dose of 0.254 gm. per kilo of body weight and arsphenamin in a dose of about 0.105 gm. per kilo, the latter being more than twice as toxic as the former for this animal under identical conditions.