Sirolimus

Indications

FELYCIN ® -CA1 (sirolimus delayed-release tablets) is indicated for the management of ventricular hypertrophy in cats with subclinical hypertrophic cardiomyopathy (HCM). Subclinical HCM refers to cats with left ventricular (LV) hypertrophy (LV wall thickness of ≥6 mm at end diastole by 2D or M-mode assessment) in the absence of systemic hypertension, other causes of compensatory myocardial hypertrophy, current or historic symptoms of congestive heart failure, arterial thromboembolism, and severe LV outflow tract obstruction.

Dosage and Administration

Administer FELYCIN ® -CA1 at a target dosage of 0.3 mg/kg orally once weekly (see Table 1). FELYCIN ® -CA1 should be swallowed whole and not chewed. Do not split or crush tablets. FELCYIN ® -CA1 should be administered in conjunction with a meal. Table 1: Dosing table (0.3 mg/kg once per week) Number of Tablets Body Weight (kg) 0.4 mg 1.2 mg 2.4 mg 2.5 - 3.2 2 0 0 3.3 - 4.8 0 1 0 4.9 - 6.4 1 1 0 6.5 - 9.6 0 0 1 >9.6 0 1 1 Due to the avaiable tablet strengths, cats weighing less than 2.5 kg cannot be accurately dosed.

Contraindications

Do not use FELYCIN ® -CA1 in cats with diabetes mellitus. Discontinue immediately if a cat receiving FELYCIN ® -CA1 is diagnosed with diabetes mellitus. The administration of FELYCIN ® -CA1 to a cat that developed diabetes mellitus was associated with the development of diabetic keto acidosis and death. (see

Warnings

User Safety Warnings: Not for use in humans. Keep out of reach of children. Contact a physician in case of accidently ingestion by humans. Accidental Ingestion of FELYCIN ® -CA1 : In case of accidental ingestion seek medical advice immediately and show the package insert or the label to the physician. Sirolimus can cause a range of adverse effects including fever, hypertension, headache, and adverse gastrointestinal effects. Drug Handling and Administration : Pregnant and breastfeeding women should avoid contact with FELYCIN ® -CA1. People with known hypersenstivity to sirolimus should administer FELYCIN ® -CA1 with caution. Always store tablets in the original packaging and only remove the required number of tablets from the blister at the time of dosing. Ensure that any tablets that are not swallowed by the cat are disposed of immediately. Avoid direct contact with vomit, saliva, or tablet remnants. When cleaning up vomit, saliva, or tablet remnants, wear gloves and wash hands afterwards. During normal handling of FELYCN ® -CA1, the coating on the tablets will prevent contact with the active ingredient, sirolimus. However, if the coating is broken down through ingestion or vomiting by the cat, exposure to sirolimus can occur. To obtain a copy of the Safety Data Sheet (SDS), contact PRN Pharmacal at 1-800-874-9764. Animal Safety Warnings: Sirolimus is a known substrate for cytochrome P-450 3A4 (CYP 3A4) and P-glycoprotein (P-gp) in humans. Administration of FELYCIN ® -CA1 with drugs that inhibit CYP 3A4 or P-gp, such as calcium channel blockers, amiodarone, azoles (e.g. ketoconazole), or cyclosporine, may increase risk for toxicity. Use caution when administering FELYCIN ® -CA1 in cats with the MDR1 mutation or when administering concomitantly with another P-gp substrate (e.g. eprinomectin and emodepside). Treatment with FELYCIN ® -CA1 could impact the cat's ability to mount an adequate immune response to vaccinations. Concurrent administration of FELYCIN ® -CA1 did not impact the cat's ability to mount an adequate immune reponse to a killed rabies vaccine (see Clinical Pharmacology and Target Animal Safety ). The impact of concurrent administration of FELYCIN ® -CA1 on vaccination for FHV-1, FCV, FPV, and FeLV has not been evaluated. Keep FELYCIN ® -CA1 in a secure location out of reach of dogs, cats and other animals to prevent accidental ingestion or overdose.

Precautions

For use only in otherwise healthy cats with subclinical HCM in the absence of other causes of compensatory myocardial hypertrophy (e.g., systemic hypertension), current or historic symptoms of congestive heart failure, arterial thromboembolism, and severe LV outflow tract obstruction. A diagnosis of subclinical HCM should be made by means of a comprehensive physical examination including blood pressure measurement to rule out systemic hypertension, and cardiac examination which should include echocardiography to confirm the presence of LV hypertrophy and radiography to rule out congestive heart failure. Echocardiographic examinnation is recommended in all cases to diagnose subclinical HCM. A diagnosis of subclinical HCM is based on an end-diastolic left ventricular wall thickness of ≥6 mm measured by 2D or M-mode assessment. Sirolimus undergoes extensive hepatic metabolism in humans. Prior to initiation of treatment with FELYCIN ® -CA1, a comprehensive physical examination and screening bloodwork including a serum biochemical profile should be conducted to rule out pre-existing liver dysfunction. Treatment with FELYCIN ® -CA1 has been associated with the elevation of the transaminase enzymes, which include alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Bloodwork should be repeated 1 to 2 months following initiation of treatment, and every 6 to 12 months thereafter. If mild transaminase elevations are observed (up to 2X the upper limit of normal (ULN)), bloodwork should be repeated in 2 months. If these values remain elevated, discontinue treatment with FELYCIN ® -CA1. Discontinue treatment with FELYCIN ® -CA1 if transaminase values exceed 2X the upper limit of normal, if other liver enzymes besides ALT or AST are elevated, or if clinical signs of liver dysfunction are noted. Available information does not indicate that FELYCIN ® -CA1 is immunosuppressive at the doses administered. The use of FELYCIN ® -CA1 in cats with chronic viral diseases like feline viral rhinotracheitis has not been evaluated. The safety and effectiveness of FELYCIN ® -CA1 has not been evaluated in cats with other cardiomyopathy phenotypes. The safety and effectiveness of FELYCIN ® -CA1 has not been evaluated in cats receiving beta blockers or corticosteroids. The safety and effectiveness of FELYCIN ® -CA1 has not been evaluated in cats with chronic kidney disease, hyperthyroidism, or other significant systemic disease. The effectiveness of FELYCIN ® -CA1 has not been evaluated in sexually intact cats. Therefore, FELYCIN ® -CA1 should not be used in animals intended for breeding.

Adverse Reactions

). Do not administere FELYCIN ® -CA1 in cats with pre-existing liver disease (see Adverse Reactions , Precautions , and Target Animal Safety ).

Description

FELYCIN ® -CA1 (sirolimus delayed-release tablets) contains the active ingredient sirolimus. FELYCIN ® -CA1 is available in 0.4 mg, 1.2 mg, and 2.4 mg tablet strengths. FELYCIN ® -CA1 are enteric film-coated biconvex tablets, plain on both sides. The 0.4 mg tablet is orange, the 1.2 mg tablet is blue, and the 2.4 mg tablet is white.

Storage

Store at 20-25˚C (68-77˚F), excursions permitted between 15-30˚C (59-86˚F). Manufactured For: PRN™ Pharmacal, Pensacola, FL 32514. PRN™ is a trademark of Pegasus Laboratories, Inc. VP00824-01 Revision Date: May-2025 felycin-ca1 0.4 carton.jpg felycin-ca1 1.2 carton.jpg felycin-ca1 2.4 carton.jpg

FDA adverse event reports

The FDA Center for Veterinary Medicine publishes the adverse event reports it receives through openFDA. The counts below are the reports naming sirolimus as an active ingredient for each species this label names, as returned on 2026-09-16, coded by the VeDDRA reaction term the reporter chose. Reactions are counted per report, so one report can appear under several terms.

These are counts, not rates. Reporting is voluntary, the number of animals treated is not known, and a widely used product accumulates reports for that reason alone. A report records that an event followed a dose; it does not establish that the product caused it. The counts say nothing about how one product compares with another.