AN almost negligible mortality ratio of 12 deaths in 12,000 cases of syphilis treated by "606" is the record which Professor Ehrlich was able to produce at the Königsberg meeting of German scientists, and in these fatalities, accidental circumstances like shock, heart failure and extreme debility were coefficients of greater moment than the acid and toxic nature of the remedy itself. As compared with the high ratio of successful treatment—probably towards 90 per cent, or more—the result is significant and striking. As the administration of "606" by injection is exceedingly painful in the first stages, Ehrlich compares it with operative surgery in that it can never be given without a certain risk in desperate cases, yet is better worth trying than to leave the patient to suffer or die. Its use is interdicted in disease of the heart, blood vessels or kidneys or in advanced stages of nervous disease, and, with characteristic reserve and caution, its author declines to make any premature claims regarding the cure of the disease with a single dose, although this is the avowed and ultimate of his therapia sterilisans
- As reported in Die Heilkunde, Berlin, October, 1910, 357. For a fuller account, see the transactions of the Deutsche Naturforscher und Aerzte as reported in the Deutsche medizinische Wochenschrift (reprinted by G. Thieme, Leipzig, 1910). Subsequent statistics show that the mortality ratio remains about one in 1,000 cases (.01 per cent.). It may be said that expression "606" is not a trade name, but a convenient abbreviation for the successful term and end of a series of 606 new compounds made and tested. Chemically "606" is the hydrochlorate of dioxydiamido-arsenobenzol, and was first tried out by Ehrlich's Japanese assistant. Dr. S. Hata. On account of its extreme acidity, it is now neutralized with caustic soda and administered as the sodium salt, the empirical formula of which might be written C12H10O2N2Na2As2. It has recently been patented as "salvarsan."