The FDA has announced the approval of all applications for use of nitarsone in animal feed will be withdrawn as of December 31, 2015. Beginning in 2016 there will be no FDA-approved, arsenic-based drugs for use in food producing animals.
In April of this year, the FDA received a letter of commitment from Zoetis Animal Health that, stating the company would suspend sale of Histostat (nitarsone) and requested that the FDA withdraw the approval for the drug by the end of 2015.
Nitarsone is the only arsenic-based animal drug that is currently approved for use in food animals. Nitarsone is approved for the prevention of blackhead disease (histomoniasis) in turkeys and chickens, but is predominantly used in turkeys.
Arsenic is in the environment as a naturally occurring substance or as a contaminant and is found in water, air, soil, and food. Published scientific reports have indicated that organic arsenic, the less toxic form of arsenic present in the arsenic-based animal drugs, could transform into inorganic arsenic, a known carcinogen.
In 2011, Alpharma, then the sponsor of 3-Nitro (roxarsone), suspended marketing of that drug after an FDA study measured higher levels of inorganic arsenic were present in the livers of chickens fed roxarsone, compared to those of untreated control chickens. The FDA has since completed additional studies that affirm the findings of its 2011 roxarsone study.
Ownership of the roxarsone application subsequently changed to Zoetis, which continued the suspension from sale of 3- Nitro and ultimately withdrew the new animal drug application for that drug on February 27, 2014. On the same day, Zoetis and Huvepharma AD voluntarily withdrew all new animal drug approvals and supplements for roxarsone, as well as two other arsenical new animal drugs, arsanilic acid and carbarsone.