FDA Gives Conditional Green Light to First-Ever Drug for Subclinical HCM in Cats: Felycin®-CA1 Now Available to Veterinarians
In a milestone for feline cardiology, Felycin®-CA1 (sirolimus delayed-release tablets) has received conditional approval from the U.S. Food and Drug Administration (FDA) for the management of subclinical hypertrophic cardiomyopathy (HCM) in cats—making it the first and only drug of its kind to reach this stage.
The drug is now available by prescription through licensed veterinarians and is distributed under the PRN Pharmacalbrand of Pegasus Laboratories, Inc., a subsidiary of PBI-Gordon Companies, Inc.
A New Hope for an Underdiagnosed Disease
Feline HCM is alarmingly common, with studies estimating it affects 1 in 7 cats—and in cats over 9 years old, that number may rise to 1 in 3. Characterized by thickening of the ventricular wall, the disease often goes unnoticed until it progresses to congestive heart failure, thromboembolic events, or sudden death. Felycin®-CA1 is designed for the subclinical stage—when cats show no outward signs, but already have ventricular thickening visible on echocardiography.
The drug uses enteric-coated delayed-release technology to deliver sirolimus in a formulation specifically tailored to cats, providing a predictable pharmacokinetic profile. Its safety and efficacy data are based on the RAPACAT study, while the HALT study is underway to pursue full FDA approval.
Addressing the Online Confusion
In its announcement, PBI-Gordon Companies was quick to draw a firm line between FDA-approved veterinary medications and the off-label, potentially dangerous use of compounded or human-formulated sirolimus (Rapamune®) in cats.
“The use of compounded rapamycin (sirolimus) or the human approved version of Rapamune® has not been approved by the FDA for the management of HCM in cats and has the potential to be very dangerous or even life-threatening if used in cats,” said Dr. Heather Davis DVM, PhD, DACVS-LA, Director of Clinical Affairs and Veterinary Services, Pegasus Laboratories, Inc.
Setting a New Standard in Feline Cardiology
This development highlights the urgent need for species-specific drug development in veterinary medicine. Until now, treatment for cats with subclinical HCM relied heavily on off-label medications, lifestyle management, and close monitoring. With the release of Felycin®-CA1, veterinarians finally have an FDA-conditionally approved option—one grounded in feline-specific research and safety data.
According to PBI-Gordon CEO Steve Clifford, this is more than a new drug. It’s a shift in how the profession approaches cardiac wellness in cats.
“We are very pleased to provide clarity and comfort to both pet owners and veterinarians by ensuring that cats with asymptomatic ventricular HCM have access to the only FDA-conditionally approved treatment for this condition.”
Available Now
Veterinarians can now prescribe Felycin®-CA1 nationwide. As the HALT study continues, this conditional approval marks a significant advancement in the treatment of one of the leading causes of death in adult cats. Don’t wait, talk to your PRN rep today!
