A federal judge has dismissed Phibro Animal Health Corporation’s lawsuit against the U.S. Food and Drug Administration over its regulatory approval process for carbadox, citing the challenge not yet “ripe” for decision.

The case stems from the FDA’s Nov. 7, 2023 decision, through its Center for Veterinary Medicine, to revoke the approved method used to establish the safety and effectiveness of carbadox. An animal drug used in swine for production purposes, such as increased rate of weight gain and improved feed efficiency, and therapeutic purposes, like controlling swine dysentery and bacterial swine enteritis, carbadox has been shown to be carcinogenic in laboratory animals. 

There are three approved New Animal Drug Applications for animal drug products containing carbadox, all held by Phibro. The FDA also published a Notice of Opportunity for Hearing on a proposal to withdraw approval of the NADAs because there is no longer an approved regulatory method to monitor the residue of carcinogenic concern in compliance with FDA’s regulation. However, unless approval of the NADAs is withdrawn, the FDA states these drugs remain available for sale and use in the United States.

Phibro claimed the decision was arbitrary and capricious under the Administrative Procedure Act, seeking declaratory and injunctive relief.

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While the FDA noted the challenged orders are part of an ongoing administrative proceeding, Phibro viewed the Revocation Order published in the Federal Register as a “final order.” The company also contended it “is already experiencing hardship from the lack of an approved carbadox regulatory method,” as the “absence of a method has tarnished the company’s reputation and undermined the goodwill built up in the carbadox brand as a safe and effective treatment for newborn pigs.” Phibro also expressed concern that because CVM concluded carbadox is an “adulterated” drug, the agency could decide to bring enforcement proceedings against Phibro at any time.  

U.S. District Judge John Bates in Washington, D.C. disagreed with both claims, noting Phibro is entitled to further agency review and has a hearing request regarding the carbadox NADA withdrawal currently pending before FDA, which the Commissioner is required to rule on. “Unless and until FDA denies Phibro’s request for a hearing on some level, the Court agrees with FDA that Phibro’s claims are not yet fit for judicial review, and that declining to rule on Phibro’s claims may “avoid[] unnecessary adjudication.”

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As for Phibro’s argument regarding potential liability for marketing an “adulterated” drug, Bates pointed out the company has not demonstrated enforcement or actual liability, is imminent, therefore “no irremediable adverse consequences [will] flow from requiring a later challenge.”

The judge also ruled that Phibro did not provide “concrete evidence” regarding reputational harm. The only evidence submitted was a letter from six senators urging the FDA to grant a hearing, citing the importance to the meat industry and FDA’s alleged departure from its typical practices. “Nothing in the letter supports Phibro’s unsubstantiated claim of reputational harm,” Bates noted. “The Court therefore is not persuaded that Phibro’s alleged hardship warrants judicial review at this time.”

Following the November decision, Phibro said in a statement it was disappointed in the actions taken by the FDA and believes fully in the safety of the product.

"Mecadox (carbadox) has been approved and sold in the United States for more than 50 years and is a widely used treatment for controlling bacterial diseases in swine, including Salmonella and swine dysentery, resulting in improved health and welfare for newly born and young pigs.

"Today’s steps are the latest in a long history of attempted measures taken by the FDA relating to carbadox that we do not believe are based on solid science. In 2016, the FDA set in motion the initial steps in a process to rescind its approval of carbadox based on its stated concerns about the persistence of carcinogenic residues. Phibro requested a hearing, and over the next four years continued an ongoing process of responding collaboratively and transparently to FDA’s inquiries to provide extensive and meticulous research and data confirming the safety of carbadox.

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"In July 2020, FDA voluntarily dismissed the 2016 proceeding and initiated a new process for review of the carbadox regulatory method, instead of following its own procedure and moving forward with a hearing that would resolve the parties’ differing interpretations of the science supporting the safety of carbadox. While Phibro has continuously offered to meet with FDA to discuss the regulatory method and has offered viable alternative methods currently being used in other countries, it is clear that, instead, the FDA is ignoring the long history of safety that Phibro has established and reaffirmed through its most recent studies. As the FDA publicly stated, going after the regulatory method 'is the most straightforward and least resource-intensive process for removing carbadox from the market.'"