Tapazole is a brand name for the generic drug methimazole. It's prescribed for people with an overactive thyroid gland. Although the FDA doesn't recommend Tapazole for animal use, vets can legally prescribe it as an "extra-label" medication. A cat given the drug may have an adverse reaction.
If your cat is getting on in years she's more likely to develop an overactive thyroid. Before your vet diagnoses the condition, you'll probably notice some of the typical symptoms of the condition, like weight loss accompanied by an abnormal eating pattern and out-of-character behavior. Once your vet has made a diagnosis, he may prescribe Tapazole, an anti-thyroid drug containing iodine, a vital mineral for good thyroid function. Tapazole reduces the thyroid function, bringing it back to a normal level.
Your vet is unlikely to prescribe Tapazole if your cat has -- in addition to an overactive thyroid -- kidney or liver problems, a blood disorder like anemia or an immune system disease. The drug has an adverse effect on your cat's bone marrow, which can aggravate existing blood disease or existing problems with liver function. Tapazole can cause issues if your cat has pre-existing kidney failure. According to the VetInfo website, what happens is, since both hyperthyroidism and kidney failure raise blood pressure, once the thyroid is successfully treated with Tapazole, the cat's blood pressure drops and the kidney problem gets worse. Make sure you tell your vet if your cat has ever had this drug before and had an allergic reaction.
Tapazole Adverse Reactions
According to PetPlace.com, cats frequently have adverse reactions to Tapazole. The more common side effects are vomiting, lethargy and a lack of appetite. If your cat needs to take this drug long-term, your vet should run regular blood tests to monitor for toxic effects, especially on the liver and blood cells. Ideally, Tapazole is given only as a short-term treatment to control the thyroid until your cat has thyroid surgery or radioactive iodine treatment.
If your cat can't tolerate Tapazole, particularly if she can't stop vomiting, your vet may suggest an alternative. Felimazole is an FDA-approved veterinary brand of methimazole available in pill form. However, there are alternatives to methimazole in any form. According to a clinical study at the Animal Medical Center in New York, one of the most successful alternative treatments is ipodate. This is a dye used in contrast radiography. Although its use as a treatment for controlling an overactive thyroid is confined to cats with mild to moderate hyperthyroidism, it is successful in some 75 percent of cases. Iopanoic acid, which is similar to ipodate, is also administered to treat hyperthyroidism.
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