The Food and Drug Administration announced March 29 that pergolide drug products, which are used to treat humans with Parkinson's disease, will be voluntarily withdrawn from the market because of the risk of serious damage to patients' heart valves.
The announcement has caused concerns for the equine industry, which often uses pergolide to treat horses with pituitary pars intermedia dysfunction, also known as equine Cushing's disease.
The products being withdrawn are Permax, the trade name for pergolide marketed by Valeant Pharmaceuticals, and two generic versions of pergolide manufactured by Par and Teva.
When asked what the FDA Center for Veterinary Medicine was doing to address veterinarians' concerns over the withdrawal, an agency spokesperson said that, until the new drug application (FDA approval) for pergolide has been withdrawn by the FDA, the drug may still be available in the pipeline for purchase, and veterinarians can legally buy and prescribe approved pergolide under the Animal Medicinal Drug Use Clarification Act.
At press time, the question of how veterinarians would even obtain the product after it was withdrawn from the market still remained. The FDA did note, however, that the effect of the withdrawal on supplies of pergolide in pharmacies will not be immediate.
"Hopefully, the raw material will remain available for use by compounding pharmacies," said Dr. Harold C. Schott, who has studied PPID and is a professor in the Department of Large Animal Clinical Sciences at Michigan State University College of Veterinary Medicine.
"Further, what is really needed is an approved product for veterinary use. Perhaps the FDA action will be the impetus for a veterinary pharmaceutical company to pursue this," Dr. Schott said.
The American Association of Equine Practitioners, through its Drug Compounding Task Force, has communicated with the FDA-CVM about the critical need for pergolide in equine medicine.
"We are hopeful that this will be resolved soon so that treatment is not interrupted for the many horses that receive the medication," said David Foley, AAEP executive director.
The AVMA Council on Biologic and Therapeutic Agents and the AVMA Clinical Practitioners Advisory Committee also recognize that pergolide is an important drug for use by veterinarians to treat horses.
"The AVMA has communicated to the FDA-CVM the medical necessity of this drug in horses," said Dr. Elizabeth Curry-Galvin, director of the AVMA Scientific Activities Division and staff consultant to COBTA and CPAC.
The Association is also aware that pharmacies had been compounding the preparation from bulk ingredients for animals even prior to the voluntary withdrawal of pergolide. According to AVMA policy, such compounding should be pursued as a last resort when veterinarians have no other treatment options. Recently, a pharmacy reported to the AVMA that, because of the human drug withdrawal, it would no longer be able to obtain the bulk ingredient for compounding in animals, which is reportedly available only from one foreign country. The AVMA has not received evidence to support such statements, but welcomes evidence if it exists.
"It would make sense for suppliers of bulk drug for animals to communicate with the FDA-CVM if interruptions in shipments are real," Dr. Curry-Galvin said. "Ideally, an animal pharmaceutical company would work with FDA to manufacture the drug with a label for veterinary use, similar to what occurred following the withdrawal of phenylpropanolamine." Such drugs are produced under strict manufacturing standards to ensure their potency and purity.