Felimazole Tablets for Cats, 2.5-mg, 100 tablets

Felimazole, treats feline hyperthyroidism, a commonly diagnosed disease in senior cats. The disease results in excess levels of thyroid hormone being produced in the thyroid gland. Symptoms can include weight loss, increased thirst and urination, vomiting, and excess activity.

Uses

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

Possible Side Effects

Side effects usually occur during the first three months of treatment. They may include loss of appetite, vomiting, and lethargy. These typically occur within the first two weeks of treatment and may eventually stop even with continuation of treatment. Less common side effects are yellowing of the gums, skin, or eyes (jaundice) which may signify liver problems. Itching of the face, scratching, or increased bleeding tendencies may occur.

View Felimazole Coated Tablets Drug Facts Sheet.

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.

Caution:

Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian.

Contraindications:

• Do not use in cats with hypersensitivity to methimazole, carbimazole, or 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, thrombocytopenia, or coagulopathies.
• Do not use in pregnant or lactating queens.

Warnings:

Methimazole has anti-vitamin K activity and may induce bleeding disorders without evidence of thrombocytopenia.

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 the drug.
• Do not break or crush tablets.
• Wear protective gloves when handling litter, feces, urine, vomit, or broken tablets from treated cats.
• Pregnant or nursing women should wear gloves when handling treated cats or their bodily fluids.
• In case of accidental ingestion or overdose, seek medical advice immediately.

Precautions:

Use of Felimazole Coated Tablets in cats with renal dysfunction should be carefully evaluated. Treatment may unmask underlying kidney disease. Cats on therapy should be monitored closely for anorexia, vomiting, facial itching, lethargy, weight loss, anemia, skin lesions, diarrhea, fever, or enlarged lymph nodes.

Concurrent use with certain medications may alter effectiveness or increase side effects. Consult your veterinarian before combining with other treatments.

Adverse Reactions:

The most common adverse reactions reported include changes in food consumption, lethargy, vomiting, diarrhea, skin lesions, and abnormal vocalization.

Additional adverse reactions reported during long-term use include depression, weight loss, coat abnormalities, weakness, agitation, jaundice, anemia, bleeding disorders, and elevated liver enzymes.

If overdosage occurs, discontinue treatment and provide supportive care.

Clinical Pharmacology:

Methimazole is an antithyroid medication that works by blocking the production of thyroid hormones. It inhibits thyroid peroxidase activity, preventing the formation of T3 and T4 hormones.

Felimazole Coated Tablets are rapidly absorbed following oral administration, with peak plasma concentrations occurring within approximately 1 to 1.5 hours after dosing.

Effectiveness:

Clinical studies demonstrated significant reductions in TT4 concentrations and improvement in hyperthyroid symptoms in treated cats. Most cats were considered clinically stable or improved throughout long-term therapy.

The average maintenance dose in long-term studies was 2.5 mg twice daily.

Animal Safety:

Safety studies showed that high doses may cause anorexia, vomiting, lethargy, anemia, thrombocytopenia, facial excoriations, and liver enlargement. Cats receiving high doses should be monitored carefully.

Storage:

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

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