First Generic Drug for Equine Cushing’s Disease

An important step in expanding treatment access for horses with PPID

The U.S. Food and Drug Administration has approved Zygolide® (pergolide tablets), the first FDA-approved generic drug for the control of clinical signs associated with Pituitary Pars Intermedia Dysfunction (PPID) in horses, commonly known as Equine Cushing’s Disease.

PPID is a chronic endocrine disorder that affects the pituitary gland and is most diagnosed in older horses. Clinical signs can include abnormal hair growth, laminitis, muscle wasting, excessive drinking and urination, lethargy, and increased susceptibility to infections.

Generic Approval and Bioequivalence

Zygolide contains pergolide, the same active ingredient as the brand-name product Prascend®, which was first approved by the FDA in 2011. As part of the generic drug approval process, the FDA determined that Zygolide tablets are bioequivalent to the reference listed drug, meaning they deliver the same amount of active ingredient into the bloodstream at a comparable rate and extent when used as directed.

Approval of the first generic pergolide product represents an important step in expanding treatment access for horses with PPID, increasing market competition, and potentially reducing long-term treatment costs for owners.

Prescription Status and Veterinary Oversight

Zygolide is available by prescription only from a licensed veterinarian. This reflects the professional expertise required to diagnose PPID accurately, establish appropriate dosing and monitoring plans, manage potential adverse reactions, and adjust treatment based on clinical response and disease progression

As with other endocrine therapies, ongoing veterinary oversight is essential for effective long-term management.

Human Safety and Handling Precautions

The FDA highlights important human safety considerations associated with pergolide, particularly during tablet handling. Tablets should not be crushed, as this may increase human exposure. Splitting or crushing pergolide tablets may cause eye irritation, headaches, or an irritating odor. And individuals with known sensitivity to ergotamine or other ergot derivatives should not administer the drug.

Human exposure to pergolide may result in nausea or vomiting, dizziness, lethargy, or low blood pressure.

These risks underscore the importance of proper handling procedures and clear communication between veterinarians and horse owners.

Sponsor Information

Zygolide is sponsored by Dechra Veterinary Products LLC, a well-established veterinary pharmaceutical manufacturer with a broad portfolio of equine and companion animal products.

Why This Approval Matters

The approval of Zygolide illustrates several key regulatory and industry dynamics, such as the FDA’s role in facilitating safe and effective generic competition in veterinary medicine, the importance of bioequivalence studies in ensuring therapeutic consistency, the continued reliance on veterinary oversight for chronic disease management, and the balance between animal treatment access and human safety protections.

For veterinarians, distributors, and manufacturers, this approval highlights how established therapies can transition into the generic marketplace while maintaining regulatory rigor.

Read the FDA announcement here.