Over four centuries later, in 1909, Paul Ehrlich introduced the compound arsphenamine
, more commonly referred to as Salvarsan, as an alternative therapy to replace mercury treatment.
The amount of silver needed to cause argyria is not known, but studies using silver to treat syphilis in the preantibiotic era showed a link between argyria and a cumulative dose of intravenous silver arsphenamine
that exceeded 4 g intravenously.
Biological products are specific types of drugs, defined to include "a virus, therapeutic serum, toxin, antitoxin, vaccine, blood, blood component or derivative, allergenic product, or analogous product, or arsphenamine
or derivative of arsphenamine
(or any other trivalent organic arsenic compound), applicable to the prevention, treatment, or cure of a disease or condition of human beings." (115) Biological products must be licensed before they can be marketed.
(6) At the time of the Study's inception in 1932, the only prior study of untreated syphilis, the so-called Oslo study, had suggested that non-treated syphilitics had lower rates of morbidity than those who received the standard arsphenamine
treatment, which compromised the immune system.
He tried every organic arsenic compound he could obtain or synthesize, and the 606th was a compound now called arsphenamine
. It did not seem unusually promising as an agent against trypanosomes, but in 1909 an assistant of Ehrlich found that it was effective against spirochetes, the agents that caused syphilis.