Neosalvarsan is a synthetic chemotherapeutic that is an

organoarsenic compound Organoarsenic chemistry is the chemistry of compounds containing a chemical bond between arsenic and carbon. A few organoarsenic compounds, also called "organoarsenicals," are produced industrially with uses as insecticides, herbicides, and fu ...

. It became available in 1912 and superseded the more toxic and less water-soluble

salvarsan 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, relapsing fever, and African trypanosomiasis. This organoarsenic compound was the fi ...

as an effective treatment for syphilis. Because both of these arsenicals carried considerable risk of side effects, they were replaced for this indication by penicillin in the 1940s. Both salvarsan and neosalvarsan were developed in the laboratory of

Paul Ehrlich Paul Ehrlich (; 14 March 1854 – 20 August 1915) was a Nobel Prize-winning German physician and scientist who worked in the fields of hematology, immunology, and antimicrobial chemotherapy. Among his foremost achievements were finding a cure ...

Frankfurt Frankfurt, officially Frankfurt am Main (; Hessian: , " Frank ford on the Main"), is the most populous city in the German state of Hesse. Its 791,000 inhabitants as of 2022 make it the fifth-most populous city in Germany. Located on it ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. Their discoveries were the result of the first organized team effort to optimize the biological activity of a

lead compound A lead compound (, i.e. a "leading" compound, not to be confused with various compounds of the metallic element lead) in drug discovery is a chemical compound that has pharmacology, pharmacological or biological activity likely to be therapeutical ...

through systematic chemical modifications. This scheme is the basis for most modern

pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field an ...

research. Both salvarsan and neosalvarsan are prodrugsthat is, they are metabolised into the active drug in the body. Although, like salvarsan, it was originally believed to contain an arsenic-arsenic double bond, this is now known to be incorrect, and exists as a mixture of differently sized rings with arsenic-arsenic single bonds.{{Cite journal, last1=Lloyd, first1=Nicholas C., last2=Morgan, first2=Hugh W., last3=Nicholson, first3=Brian K., last4=Ronimus, first4=Ron S., date=2005, title=The Composition of Ehrlich's Salvarsan: Resolution of a Century-Old Debate, journal=Angewandte Chemie International Edition, volume=44, issue=6, pages=941–944, doi=10.1002/anie.200461471, pmid=15624113, hdl=10289/207, issn=1521-3773, url=https://researchcommons.waikato.ac.nz/bitstream/10289/207/1/content.pdf, doi-access=free

References

Sulfinates Antibiotics Organoarsenic compounds Phenols Paul Ehrlich German inventions