Felimazole Coated Tablets for Cats

Felimazole treats hyperthyroidism in cats, a condition in which too much thyroid hormone is produced. It will not cure the disease, but will usually control it if given for the rest of the cat's life. treats hyperthyroidism in cats, a condition in which too much thyroid hormone is produced. It will not cure the disease, but will usually control it if given for the rest of the cat's life.

Indication

Felimazole Coated Tablets (methimazole) are indicated for the treatment of hyperthyroidism in cats.

Key Benefits

• Controls the symptoms of hyperthyroidism for an improved quality of life
• Treats hyperthyroidism without surgery or anesthesia
• Available in a dosage size specifically for cats

How It Works

Active Ingredient

Methimazole

View Felimazole package insert.

Dosage

The starting dose of Felimazole Coated Tablets is 2.5 mg administered every 12 hours. Following 3 weeks of treatment, the dose should be titrated to effect based on individual serum total T4 (TT4) levels and clinical response. Dose adjustments should be made in 2.5 mg increments. The maximum total dosage is 20 mg per day divided, not to exceed 10 mg as a single administration.

Hematology, biochemistry, and TT4 should be evaluated prior to initiating treatment and monitored after 3 weeks and 6 weeks of treatment. Thereafter, bloodwork should be monitored every 3 months and the dose adjusted as necessary. Cats receiving doses greater than 10 mg per day should be monitored more frequently.

Administration

Felimazole tablets are given by mouth. Methimazole, the active ingredient, is very bitter. Felimazole comes as a coated tablet for ease of administration. Do not break or crush the tablet. Always follow the dosage instructions provided by your veterinarian. If you have difficulty giving the medication, contact your veterinarian. Wash hands with soap and water after giving the medication.

Blood levels of thyroid hormone will be checked by your veterinarian at regular intervals, and the dose increased or decreased as needed. The lowest effective dose should be used.

This medication should only be given to the pet for whom it was prescribed.

Always follow the dosage instructions provided by your veterinarian. If you have difficulty giving the medication, contact your veterinarian. This medication should only be given to the pet for which it was prescribed.

Storage

Store at controlled room temperature 25°C (77°F) with excursions between 15°-30°C (59°-86°F) permitted. Keep away from children and pets. Keep the container tightly closed in order to protect from moisture.

Contraindications

Do not use in cats with hypersensitivity to methimazole, carbimazole or the excipient, polyethylene glycol.

Do not use in cats with primary liver disease or renal failure.

Do not use in cats with autoimmune disease.

Do not use in cats with hematological disorders (such as anemia, neutropenia, lymphopenia, or thrombocytopenia) or coagulopathies.

Do not use in pregnant or lactating queens. Laboratory studies in rats and mice have shown evidence of teratogenic and embryotoxic effects of methimazole.

Warnings

Methimazole has anti-vitamin K activity and may induce bleeding diathesis without evidence of thrombocytopenia. See ADVERSE REACTIONS.

Human Warnings

Not for use in humans. Keep out of reach of children. For use in cats only.

Wash hands with soap and water after administration to avoid exposure to drug. Do not break or crush tablets. Wear protective gloves to prevent direct contact with litter, feces, urine, or vomit of treated cats, and broken or moistened tablets. Wash hands after contact with the litter of treated cats.

Methimazole is a human teratogen and crosses the placenta concentrating in the fetal thyroid gland. There is also a high rate of transfer into breast milk. Pregnant women or women who may become pregnant, and nursing mothers should wear gloves when handling tablets, litter or bodily fluids of treated cats.

Methimazole may cause vomiting, gastric distress, headache, fever, arthralgia, pruritus, and pancytopenia. In the event of accidental ingestion/overdose, seek medical advice immediately and show the product label to the physician.

Precautions

Use of Felimazole Coated Tablets in cats with renal dysfunction should be carefully evaluated. Reversal of hyperthyroidism may be associated with decreased glomerular filtration rate and a decline in renal function, unmasking the presence of underlying renal disease. Due to potentially serious adverse reactions such as hepatopathy, immune-mediated anemia, thrombocytopenia, and agranulocytosis, cats on methimazole therapy should be monitored closely for any sign of illness including anorexia, vomiting, head/facial pruritus or edema, depression/ lethargy, weight loss, anemia, skin lesions, diarrhea, fever, or lymphadenopathy. If a cat becomes ill while on Felimazole Coated Tablets, the drug should be stopped and appropriate hematological and biochemical testing should be done.

Anticoagulants may be potentiated by the anti-vitamin K activity of Felimazole Coated Tablets. Concurrent use of phenobarbital may reduce the clinical effectiveness of Felimazole Coated Tablets. A reduction in dose of certain drugs (?-adrenergic blocking agents, digitalis glycosides, and theophylline) may be needed when the patient becomes euthyroid.

Methimazole is known to reduce the hepatic oxidation of benzimidazole anthelmintics (e.g. fenbendazole), leading to increased plasma concentration of these anthelmintics when administered concurrently. Felimazole Coated Tablets caused delayed maturation of the testes in young male cats in the 12-week safety study. The safety of Felimazole Coated Tablets has not been evaluated in male cats intended for breeding.

Possible Side Effects

You may see changes in appetite, vomiting, diarrhea, skin lesions, lethargy, or abnormal vocalization. These usually occur within the first two weeks of treatment and may stop even with continuation of treatment.

Less common side effects include liver problems resulting in the above signs plus yellowing of the gums, skin, or eyes, itching of the face resulting in scratching, bleeding tendencies, swollen lymph nodes, anemia, and low white blood cell counts. Your veterinarian will determine if these effects necessitate stopping the medication and treating with surgery or radioactive iodine therapy.

Treatment with methimazole may unmask hidden kidney disease.

If your pet is unusually tired, has a fever (temperature over 103), or shows signs of bruising or bleeding, contact your veterinarian immediately.

If your pet experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately.

If your pet experiences an allergic reaction to the medication, signs may include facial swelling, hives, scratching, sudden onset of diarrhea, vomiting, shock, seizures, pale gums, cold limbs, or coma. If you observe any of these signs, contact your veterinarian immediately.