The FDA is warning veterinarians and horse owners that one lot of compounded combination drug product containing pyrimethamine and toltrazuril has been associated with adverse events in at least three horses, two in Maine and one in Ohio, according to a release.
Testing completed by the agency found that this lot of the product contained approximately 18 to 21 times the pyrimethamine indicated on the label. High doses of this medication can cause clinical signs such as seizures, fever and death, the release notes.
Rapid Equine Solutions of Aston, Pennsylvania, compounded the product, which was labeled as containing toltrazuril 416 mg/ml and pyrimethamine 17 mg/ml, and packaged in 60 ml oral paste syringes for the treatment of the neurologic disease Equine Protozoal Myeloencephalitis (EPM).
The products from the lot have been accounted for and are no longer in distribution. The company learned of the adverse events in late May and initiated a recall to consumers the same day. The FDA is working with company and state agencies to investigate the adverse events, the release states.
According to the release, an incident linked to a different compounder also involved erroneously formulated compounded pyrimethamine/toltrazuril products that led to four equine deaths in 2014. It notes that compounded products are not FDA-approved animal drugs and that toltrazuril is not approved for use in horses.
There are several drugs that are FDA-approved for the treatment of EPM, according to the FDA, and the agency encourages horse owners to consult their veterinarian for treatment advice. The agency asks veterinarians, horse owners and caretakers to report adverse events in horses being treated with compounded pyrimethamine-containing products. That can be done here.