UPDATED December 17, 2015: The approval of all applications for use of nitarsone in animal feed is withdrawn as of December 31, 2015. Following this action, there are no FDA-approved, arsenic-based drugs for use in food producing animals.
April 1, 2015
The U.S. Food and Drug Administration today announced that it has received a letter of commitment from Zoetis Animal Health that, by the fall of 2015, the company will suspend sale of Histostat (nitarsone) and formally request 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.
Zoetis holds three approved animal drug applications for nitarsone: Histostat-50 (approved for use in chickens and turkeys for prevention of blackhead); and two combination use approvals, BMD/Histostat and Albac/Histostat (approved for use in turkeys for prevention of blackhead). All three uses would cease to be marketed upon withdrawal of the nitarsone approval.
Blackhead is a disease that occurs seasonally in certain parts of the country and is a cause of significant mortality in turkeys. Currently, nitarsone is the only animal drug approved for managing this disease in turkeys. Under the phase-out plan being announced today, nitarsone will continue to be available for the 2015 season. This strategy allows affected producers the opportunity to consider alternatives for managing this disease in the future.