FDA Announces Plans to Withdraw Carbadox; Phibro Responds

April 13, 2016 — 

The U.S. Food and Drug Administration’s Center for Veterinary Medicine (CVM) has taken the first step toward rescinding its approval of the use of carbadox to treat swine because the drug may leave trace amounts of a carcinogenic residue. Phibro Animal Health, the drug’s manufacturer, issued a statement expressing confidence in the drug’s safety and noted that “to date we have not seen any hazardous residues of carbadox being detected from pig meat treated in accordance with the approved label.” [Sources: FDA Press Release and Phibro Animal Health, 4/8/2016]

CVM’s action comes after the center recently reexamined the safety profile of the drug and conducted a preliminary risk characterization that indicated there could be potential risk to human health from ingesting pork, especially pork liver, derived from carbadox-treated pigs.

“The manufacturer of carbadox has failed to provide sufficient scientific data to demonstrate the safety of this drug given evidence that carbadox may result in carcinogenic residues,” said Michael R. Taylor, FDA deputy commissioner for foods and veterinary medicine. “As a result, FDA’s Center for Veterinary Medicine is taking legal action to remove this product from the marketplace.”

According to Phibro’s statement, “several years ago, in response to the availability of more advanced analytical detection methods, the FDA began to raise questions about the persistence of residues in tissue longer than previously determined. Since that time, Phibro Animal Health has cooperated fully with the FDA's inquiries, including undertaking comprehensive, rigorous new studies using the latest and most sensitive technology available. Phibro has been providing the data to the FDA as it is generated, and in accordance with the schedule submitted to the agency, and to date that evidence has been positive regarding the safety of Mecadox and has reiterated the safety of Mecadox when used in accordance with the label. As Phibro has told the FDA, our studies are due to be completed in the next 90 days and we expect that the remaining evidence will support the continued safe use of Mecadox.” The statement goes on to say that Phibro “intends to request a hearing and refute the allegations.”

This announcement by the FDA does not prohibit the sale or use of Mecadox in the United States. Furthermore, the FDA is not recommending that people make changes in their food choices while the agency is working to remove carbadox from the market. Potential cancer risks are based on an assumed lifetime of consuming pork liver or other pork products containing carbadox residues, and short-term changes in diet are unlikely to affect a person's lifetime risk.

According to the FDA, in July 2014, the Codex Alimentarius Commission determined there is no safe level of residues of carbadox or its metabolites in food that represents an acceptable risk to consumers. This was based on the Food and Agriculture Organization of the United Nations/World Health Organization Codex Committee on Residues of Veterinary Drugs in Foods’ conclusions on the available scientific information.