Frequently Asked Questions

Sirofel™ contains Sirolimus (Rapamycin), a compound that inhibits the mechanistic target of rapamycin (mTOR) pathway. Pathological cellular hypertrophy in feline heart muscle is heavily regulated by mTOR. By selectively inhibiting this pathway, Sirofel™ helps slow or prevent abnormal thickening of the left ventricle wall, preserving cardiac volume and blood outflow.

Sirolimus is highly sensitive to the acidic environment of the stomach and can degrade quickly, losing therapeutic value. Sirofel™ tablets are engineered with an advanced enteric coating. This coating allows the tablet to pass through the stomach completely intact, releasing the active ingredient in the neutral-pH environment of the duodenum for peak absorption.

Unlike daily veterinary drugs, Sirolimus is administered on an intermittent, weekly schedule. Research indicates that a single weekly dose is sufficient to achieve optimal cardiac tissue remodeling control while dramatically reducing the likelihood of systemic side effects.

The starting weekly dose is calculated based on cat weight (typically 0.3 mg/kg for Stage B1 subclinical HCM, and 0.4 mg/kg for Stage B2 subclinical HCM). You can use the dosage calculator on our home page for preliminary recommendations. Always consult with a veterinary cardiologist for a formal dosage schedule.

Cat owners should measure the Resting Respiratory Rate (RRR) daily. RRR should be measured when the cat is completely asleep. An RRR of less than 30 breaths per minute is normal. A consistent rise above 30 indicates potential pulmonary congestion and is a clinical sign of heart distress.

mTOR inhibitors like Sirofel™ are designed as preventive interventions during the subclinical stages (Stage B1/B2) to slow down ventricular remodeling before heart failure occurs. In cases of active Congestive Heart Failure (e.g. fluid in lungs), standard heart medications (diuretics like furosemide, ACE inhibitors) are mandatory. Sirofel™ can be used alongside standard CHF drugs under veterinary supervision.