The FDA says it is seeking an injunction against Franck's Compounding Lab, of Ocala, "to prevent the company from introducing adulterated, misbranded, and unsafe animal drugs into interstate commerce".
The action comes only a fortnight after civil court action was initiated against Franck's in which more than $US4 million is sought for the loss of the polo ponies.
Each of the horses had been given a preparation mixed by Franck's. Necropsies performed on the horses revealed significantly increased selenium levels.
The horses, from the Venezuelan-owned Lechuza Caracas team, began collapsing on April 19 as they were unloaded from trailers at the International Polo Club Palm Beach before a US Polo Championship match.
Franck's Pharmacy chief operations officer Jennifer Beckett said last April that the strength of an ingredient in the preparation was incorrect, but would not name it.
The civil court action, in Palm Beach County Court, has been filed by Quantum Management Company and three player/owners, Juan Martin Nero, Guillermo Caset, and Nicolas Espain.
The FDA, which filed its action on April 16, said it was concerned that the company's continued compounding practices posed a significant public health risk, as evidenced by the deaths of 21 polo ponies after having been given a drug compounded by Franck's.
The injunction bid was filed by the Department of Justice on behalf of FDA in the US District Court for the Middle District of Florida and would permanently bar the company, officially known as Franck's Lab Inc, and its chief executive Paul W. Franck, from compounding animal drugs from bulk ingredients without FDA approval.
It said the pharmacy makes animal drugs, in most instances from active pharmaceutical ingredients, and distributes them throughout the country.
Compounding is the term used for combining, mixing, or altering ingredients to create a medication tailored to the needs of an individual patient.
Animal drugs compounded from bulk ingredients do not undergo FDA review and are not approved by the agency.
"Many of Franck's illegal products are copies very similar to available drugs that have been approved by the FDA," the agency said.
"FDA recognises the benefit of the traditional practice of pharmacy compounding - providing a service in response to a valid prescription to accommodate the specialised needs of a particular patient," said veterinarian Bernadette Dunham, director of the agency's Centre for Veterinary Medicine.
"But when compounders like Franck's circumvent, and thus undermine, the statutory drug approval process by manufacturing drugs under the guise of pharmacy compounding, we are concerned that poorly compounded drugs can jeopardise the health of animals."
Franck's had been inspected and warned about its illegal behaviour, as recently as December last year, but it has failed to cease its illegal practices, the agency said.