Salvarsan is a drug that was introduced at the beginning of the 1910's as the treatment for which disease?

Arsphenamine, also known as Salvarsan or compound 606, is a drug that was introduced at the beginning of the 1910s as the first effective treatment for syphilis and African trypanosomiasis. This organoarsenic compound was the first modern antimicrobial agent.

Arsphenamine was first synthesized in 1907 in Paul Ehrlich's lab by Alfred Bertheim. The antisyphilitic activity of this compound was discovered by Sahachiro Hata in 1909, during a survey of hundreds of newly synthesized organic arsenical compounds. Ehrlich had theorized that by screening many compounds, a drug could be discovered that would have anti-microbial activity but not kill the human patient.

Ehrlich's team began their search for such a "magic bullet" among chemical derivatives of the dangerously toxic drug atoxyl. This project was the first organized team effort to optimize the biological activity of a lead compound through systematic chemical modifications, the basis for nearly all modern pharmaceutical research.