History of the discovery of sulfaquinoxaline as a coccidiostat

Sulfaquinoxaline played an important part in the demotion of roast chicken from vaunted Sunday-dinner status to an unrespected position on the everyday menu of the Western world. It had its origins in the chemical synthetic program that sprang from the introduction of sulfonamide drugs into human medicine in the 1930s. The program was sustained through the years of World War II despite declining clinical use of that chemical class. Several sulfa drugs were known to be active against the sporozoan parasite (Plasmodium spp.) that causes malaria, but were not satisfactory in clinical practice. A sulfonamide that had a long plasma half-life would ipso facto be considered promising as an antimalarial drug. Sulfaquinoxaline, synthesized during the war, was such a compound. It proved too toxic to be used in human malaria, but was found to be a superior agent against another sporozoan parasite, Eimeria spp., the causative agent of coccidiosis in domestic chickens. In 1948 sulfaquinoxaline was introduced commercially as a poultry coccidiostat. It was not the first sulfonamide found active against Eimeria spp. in poultry, but its practical success in disease control firmly established the routine incorporation of anticoccidial drugs in poultry feed. In this way, the drug exerted a major impact on the worldwide production of poultry meat. Although it has long been eclipsed by other drugs in poultry management, it continues to be used in other host species. This article describes the discovery of sulfaquinoxaline as a practical therapeutic agent, and examines the way in which the discovery arose from a partnership between industry and academia.