FDA Conditionally Approves Drug for Management of Ventricular Hypertrophy in Cats
March 14, 2025
Today, the U.S. Food and Drug Administration is announcing the conditional approval of Felycin-CA1 (sirolimus delayed-release tablets) for the management of ventricular hypertrophy in cats with subclinical hypertrophic cardiomyopathy (HCM). This is the first product approved for use in cats with HCM for any indication.
Cardiomyopathy is a disease of the heart muscle. HCM in cats causes thickening of the heart's left ventricle. It is the most common heart disease in cats and is one of the most common causes of death in cats. While the cause is unknown in most cases, HCM is associated with a genetic mutation in certain breeds, such as Maine Coons, Ragdolls, and Persians. HCM is a progressive disease. Cats in the subclinical phase have thickening of their heart wall but do not show clinical symptoms of the disease yet. Cats may live for years in the subclinical phase, while others may progress to congestive heart failure, arterial thromboembolism, or sudden death.
An animal drug is eligible for conditional approval if it addresses a serious or life-threatening disease, or addresses an unmet animal or human health need, for which demonstrating effectiveness would require a complex or particularly difficult study or studies. Felycin-CA1 met this requirement because subclinical HCM often progresses to clinical HCM, which substantially impacts day-to-day functioning in cats and can be fatal. As the first drug approved for use in cats with ventricular hypertrophy due to subclinical HCM, Felycin-CA1 addresses an unmet animal health need. In addition, demonstrating effectiveness of Felycin-CA1 would require a complex or particularly difficult study or studies because detecting subclinical HCM requires advanced diagnostic tests, making it difficult to enroll sufficient numbers of eligible cats.
At higher doses, the active ingredient in Felycin-CA1, known as sirolimus, is used as an immunosuppressant in humans receiving organ transplants. Felycin-CA1 is given to cats at a target dose of 0.3 mg/kg orally once weekly. The dose is not expected to be immunosuppressive in cats. The sponsor conducted a vaccine response study to show that it should not impact a cat’s ability to mount an immune response to the rabies vaccine.
Felycin-CA1 is only available by prescription from a licensed veterinarian. Cats should be screened for pre-existing liver disease before starting Felycin-CA1, and it should not be used in cats with pre-existing liver disease or diabetes mellitus.
Felycin-CA1 is available in 0.4 mg, 1.2 mg, and 2.4 mg tablet sizes and is sponsored by TriviumVet based in Waterford, Ireland.
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Issued by FDA Center for Veterinary Medicine.
For questions, Contact CVM.