No hard date yet for Zilmax's return, drugmaker says

A certification process is ready and field evaluations are to begin in early 2014 for Merck’s cattle feed additive Zilmax — but the company says it’s still too soon to say when the drug will be back on the market.

Merck’s animal health arm in August suspended sales of the popular growth-promoting additive in Canada and the U.S. after major meat packer Tyson Foods stopped accepting cattle treated with the drug.

Cargill, another major packer, followed suit later that month, and the Chicago Mercantile Exchange (CME) said in September it would no longer accept delivery of cattle fed Zilmax.

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Tyson said its decision followed observations that some animals arriving at its packing plants were having difficulty walking or moving. The company didn’t specifically lay the blame on Zilmax but had noted that experts suggested the use of the drug may be a cause.

Merck said at the time it will retrain and certify beef producers in administering the drug to cattle, and run a “scientific audit,” following Zilmax-fed cattle from feed yards to packing plants, to determine potential causes of lameness and other mobility issues.

The drug company said Friday it has made “considerable progress” on its plan over the past 90 days, but it’s “too early to determine when Merck Animal Health will return Zilmax back to the market in the United States and Canada.”

Zilmax — Merck’s brand name for zilpaterol hydrochloride, a beta-2 agonist billed to promote weight gain, feed efficiency and carcass leanness — is marketed in Canada through Intervet.

The product, nicknamed “Vitamin Z” in some feedlots, has been approved in Canada and the U.S. since 2009 and 2007 respectively.

“Guiding principles”

The company on Friday laid out further details of its formal certification process for Zilmax, in which “every feedyard team member, nutritionist and veterinarian” who treats with Zilmax or consults on feeding it to cattle must be “trained annually on the proper use of the product.”

Said training is to focus on “safety practices, product handling, mixing protocols, cattle management, product inventory, record-keeping and clean-out procedures,” Merck said.

“Every certified operation will also be required to pass an initial homogeneity test to ensure proper mixing practices, as well as four additional feed mix tests throughout the year.”

Any feedyard taking part in Merck’s planned “field evaluations” of Zilmax, expected to begin in the first quarter of 2014, will first need to be certified, the company said.

“Guiding principles” of the field evaluations are to include observation of cattle throughout the system, both before and after receiving Zilmax, at the feedyard and at the packing plant, the company said.

Cattle mobility will be evaluated by “trained third-party experts utilizing an established mobility scoring system,” Merck said, and “potential compounding factors” such as nutrition, transportation, receiving facilities, flooring surfaces and cattle management and handling practices will also be reviewed.

A “well-known independent epidemiologist and veterinarian” will oversee the evaluations, serve as principal investigator, collect all data, analyze results and publicly communicate findings, the company said.

Merck remains “highly confident in the safety of Zilmax, which is supported by the results of more than 30 studies, totaling 65,000 cattle that were conducted by well-respected universities and third-party experts,” KJ Varma, Merck Animal Health’s senior vice-president for global R+D, said in a company release.

Merck, he said, believes the field evaluations “will support the results of previous studies and the safety of the product.” — AGCanada.com Network