The U.S. Food and Drug Administration announced May 15 that four horses have died after receiving compounded drug products, containing pyrimethamine and toltrazuril, used to treat equine protozoal myeloencephalitis. The compounds originated at Wickliffe Pharmacy in Lexington, Ky.
Six additional horses have suffered adverse effects, including fever and seizure, from the medication but are now recovering.
One lot of the compound was a paste and one was an oral suspension. The FDA reports that all of the products in the lots are accounted for and are no longer in distribution.
“[The] FDA is working with the pharmacy and state partners to investigate these adverse events,” stated an FDA release. “At this time, FDA testing indicates that one lot of product contained higher levels of pyrimethamine than the labeling indicates. Adverse events associated with high doses of pyrimethamine include seizures, fever and death.”
Two of the horses were located in Kentucky and eight in Florida.
“These compounded combination products are not approved animal drugs,” stated the FDA release. “Additionally, toltrazuril is not approved for use in horses. In general, FDA has serious concerns about unapproved animal drugs, including certain compounded animal drugs.
“Drugs that have been evaluated and approved by FDA for the treatment of EPM include ponazuril, diclazuril, and a combination drug of pyrimethamine and sulfadiazine,” the release continued.
In a statement, Wickliffe said they are working with federal officials to learn what caused the adverse effects. Wickliffe also said that the compound had been prescribed and dispensed only to horses with those prescriptions.
“We wish to extend our deepest sympathies to the owners of, and equine professionals associated with, the horses that have died or been euthanized,” stated their release.
Want to know more about compounded drugs? Read this comprehensive article the Chronicle published in their print magazine, "Compounded Drugs Have Helped Horsemen For Ages".