Generic cattle drug’s sale halted after complaint

Action follows lawsuit alleging likely "off-label" use
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Two cows
(Photo by Greg Cima)

Federal authorities have halted sales of a generic drug to treat respiratory disease in cattle as they reconsider its approval.

The review is a response to a petition and lawsuit by the sponsor of the original patented drug, Bayer Healthcare, which argued that the generic alternative often would be used in an "off-label" manner. As cited in court documents, that use is a patented label application on the Bayer drug through mid-2015.

The company’s arguments are not based on the patent, but rather, on a claim that the Food and Drug Administration broke the law by approving a drug likely to be used in a way contrary to the label.

The FDA is prohibiting marketing, sales, and shipment of Norbrook Laboratories’ Enroflox 100 for use in cattle during the agency’s review of that generic drug’s approval. It was approved earlier this year for use in cattle and swine and is a competitor of Bayer’s Baytril 100.

In April, U.S. District Judge Rosemary M. Collyer had granted a request by Bayer for a temporary order that the FDA suspend approval of Norbrook’s product. Later that month, court documents state that the FDA decided it was in the public interest to review the approval of the generic drug, and Collyer remanded the case to the agency and ended the lawsuit.

While the brand-name drug was labeled for administration to cattle in a single dose or over multiple days, the generic was labeled for administration to cattle only over multiple days, according to court documents. Bayer’s patent on a single-dose administration expires in June 2015.

Bayer officials had said in a 2006 petition to the FDA that about three-quarters of cattle treated with Baytril 100 for bovine respiratory disease received a single-dose treatment. The petition cited a survey of 300 veterinarians who administer the drug.

Company officials argued in the petition that most buyers of a generic alternative would administer that drug in a single dose, even if the generic drug were labeled only for multiple-day treatment. They also said a company manufacturing a generic version of the drug would promote such extralabel use.

The FDA did not provide a final response to the petition, which was still pending when Enroflox 100 was approved earlier this year, court documents state. Staci Gouveia, a spokeswoman for Bayer, said her company filed the suit because the FDA did not respond to the petition and because Bayer sees the generic drug’s approval as illegal.

Bayer further argued in court documents that, with approval of the generic drug, Bayer would lose money, employees, and research and development resources.

Chip Whitlow, marketing manager for Norbrook, said the company was declining to comment because of the ongoing proceedings.