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  1. CVM Updates

FDA Approves First Generic Methimazole for Treating Hyperthyroidism in Cats

On July 9, 2024, the FDA updated this communication to clarify that Felanorm is only available in a 1 mL dosing syringe (and not a 5 mL syringe).

July 9, 2024

The U.S. Food and Drug Administration has approved Felanorm, the first generic methimazole oral solution for the treatment of hyperthyroidism in cats. 

Felanorm contains the same active ingredient (methimazole) as the approved brand name drug product, Felimazole Coated Tablets, which were first approved on May 27, 2009. In addition, the FDA determined that Felanorm contains no inactive ingredients that may significantly affect the bioavailability of the active ingredient.

Felanorm is only available by prescription from a licensed veterinarian because professional veterinary expertise is needed to diagnose hyperthyroidism in cats and to determine whether Felanorm is an appropriate treatment. Continued veterinary monitoring is also needed to ensure that the dose continues to be appropriate to control the cat’s hyperthyroidism, as this disease can progress over time. 

Felanorm is supplied in 30 mL or 100 mL bottles with a 1 mL dosing syringe. Felanorm is dosed in 2.5 mg increments, every 12 hours. 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.

People administering Felanorm should wear protective single use, impermeable (e.g., latex or nitrile) gloves when administering the solution and should wash their hands with soap and water after administration to avoid exposure to the drug. 

Felanorm is sponsored by Norbrook Laboratories Ltd. based in the United Kingdom.

For more information:

Issued by FDA Center for Veterinary Medicine.
For questions, Contact CVM.

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