Felimazole® Tablet

• Description: Antithyroid agent
• Other Names for this Medication: Tapazole®, Methimazole
• Common Dosage Forms: Veterinary: 2.5 mg & 5 mg sugar-coated tablets. Topical gels may be available from compounding pharmacies.
• Human: 5 mg & 10 mg tablets.

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

How is this medication useful? 

Methimazole is given to lower thyroid hormone levels. It is important to understand that Methimazole does not cure an overactive thyroid but controls the disease if given to the animal for the rest of its life.

Veterinarians may also prescribe Methimazole for dogs to protect their kidneys while they are receiving cisplatin chemotherapy.

• The FDA has approved this drug for treating hyperthyroidism in cats.
• The FDA allows veterinarians to prescribe and use products containing this drug in other animal species in certain situations.

You and your veterinarian can discuss why this drug is the most appropriate choice.

Indications:

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

Dosage and Administration:

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.

What are the side effects of this medication? 

Methimazole is usually well tolerated, but side effects can occur; most happen in the first 3 months of therapy.

Common but not serious side effects:

• Vomiting.
• Decreased appetite or loss of appetite.
• You do not have to be overly concerned if you see any of these signs unless they are severe, are persistent, or worsen.
• Contact your veterinarian if this happens.

Side effects that may be serious or indicate a serious problem: 

• Fever.
• Bruising.
• Depression, lethargy (lack of energy).
• Severe weakness (rare).
• Itching and scratching (particularly of the face) to the point that the animal causes bleeding.
• Sores (rare).

If you see any of these signs, contact your veterinarian immediately.

If you have any other questions about this medication, contact your veterinarian or pharmacist.

Important Safety Information:

CAUTION: As with all drugs, side effects may occur. The most commonly reported side effects are anorexia, vomiting, head/facial pruritus or edema, depression/lethargy, weight loss, anemia, elevated liver enzymes, skin lesions, elevated BUN, diarrhea, and thrombocytopenia. FELIMAZOLE Coated Tablets are not for use in pregnant or lactating queens, or cats with renal, hepatic, or hematological disorders. In some reported cases, the patients recovered after adverse signs were recognized, the drug was withdrawn, and veterinary care was applied. In some cases, death (or euthanasia) has been reported as an outcome of the adverse reactions listed above. Methimazole has anti-vitamin K activity and may induce bleeding diathesis without evidence of thrombocytopenia. Refer to the prescribing information for complete details or visit www.dechra-us.com.