Felimazole Main Uses
Treatment of Feline Hyperthyroidism: Indicated for the long-term medical management of hyperthyroidism in cats. Effectively manages clinical symptoms such as weight loss despite increased appetite, excessive thirst (polydipsia), frequent urination (polyuria), hyperactivity, and unkempt coat.
Pre-Surgical Stabilization: may be used by veterinarians to stabilize cats prior to thyroidectomy.
 
Felimazole Active Ingredients
Active Ingredient: Methimazole.
Mechanism: An antithyroid agent that blocks the biosynthesis of thyroid hormones. It works by inhibiting the enzyme thyroid peroxidase. This prevents the iodination of thyroglobulin, thereby stopping the synthesis of T3 (triiodothyronine) and T4 (thyroxine).
 
Felimazole Dosage & Administration
Starting Dosage: The typical initial dose is 2.5 mg administered orally every 12 hours.
Titration: After 3 weeks of treatment, the veterinarian will perform blood tests (TT4) and clinical assessments to adjust the dose in increments of 1.25 mg or 2.5 mg.
Maintenance Range: The dose is titrated to the lowest effective amount to maintain normal hormone levels. The maximum total daily dosage should not exceed 15 mg.
Administration Timing: Can be given with or without food. If a cat vomits on an empty stomach, the dose should be given with a small amount of food.
Important Constraint: Tablets must not be broken or crushed, as they are sugar-coated to mask the bitter taste and to prevent human exposure to the active ingredient.
 
Felimazole Side Effects & Safety
Common Side Effects: Most occur within the first 3 months and include vomiting, decreased appetite (anorexia), and lethargy.
Serious Adverse Reactions: Rarely, cats may experience severe itching (facial pruritus/excoriation), liver disease (hepatopathy), or blood disorders such as anemia, low white blood cell count (neutropenia), or low platelet count (thrombocytopenia).
Contraindications: Do not use in cats with primary liver disease, renal failure, autoimmune disease, or pre-existing blood/coagulation disorders.
Human Safety Warning: Methimazole is a suspected human teratogen. Pregnant women or women of child-bearing age should wear gloves when handling the tablets and when cleaning the litter box of a treated cat.
Monitoring: Requires regular veterinary follow-ups (initially at 3 and 6 weeks, then every 3 months).
Storage: Store between 15°C and 25°C. Keep the container tightly closed to protect from moisture. Methimazole is known to be sensitive to light. Protect the tablets from light if removed from the original container and not used immediately.
 
Felimazole Manufacturer Information
Manufacturer: Dechra
Official Website: https://www.dechra.ca/
Brand Introduction: Dechra is a global specialist in veterinary pharmaceuticals. Felimazole holds a unique position as a widely approved veterinary-specific formulation of methimazole in Canada, designed specifically to meet the metabolic needs of felines with thyroid disorders.