Arsphenamine

Arsphenamine, also known as Salvarsan or compound 606, is an antibiotic drug that was introduced at the beginning of the 1910s as the first effective treatment for the deadly infectious diseases syphilis, relapsing fever, and African trypanosomiasis.

[9] This significantly complicated administration, as the drug had to be dissolved in several hundred milliliters of distilled, sterile water with minimal exposure to air to produce a solution suitable for injection.

Some of the side effects attributed to Salvarsan, including rashes, liver damage, and risks of life and limb, were thought to be caused by improper handling and administration.

[10] This caused Ehrlich, who worked assiduously to standardize practices, to observe, "the step from the laboratory to the patient's bedside ... is extraordinarily arduous and fraught with danger.

"[7] Ehrlich's laboratory developed a more soluble (but slightly less effective) arsenical compound, Neosalvarsan (neoarsphenamine), which was easier to prepare, and it became available in 1912.

The structure of arsphenamine has been proposed to be akin to azobenzene ( A ), but chemical studies published in 2005 suggest [ 1 ] that salvarsan is actually a mixture of the trimer ( B ) and the pentamer ( C ).
Salvarsan treatment kit for syphilis, Germany, 1909–1912 [ 5 ]