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Helping Our Cats Live Healthier Lives—Information about Two FDA-Approved Drugs for Cats

Feline health is important. In May 2018, FDA approved two drugs for cats—Mirataz (mirtazapine transdermal ointment) to manage undesired weight loss and Semintra (telmisartan oral solution) to control high blood pressure. Both drugs are available only with a veterinarian’s prescription.

Mirataz for Managing Undesired Weight Loss in Cats

Your 13-year-old cat, Sunny, is losing weight. He won’t eat even though you offer him several varieties of both canned and dry food, warm up the canned food in the microwave, and even try baby food. Despite your best efforts, he sniffs at the food and takes a few licks, but then walks away. You take Sunny to your veterinarian who prescribes Mirataz to manage his weight loss.

Weight loss is often the first sign of illness in cats. For example, cats with kidney or dental disease or those with stomach and intestinal problems often lose weight. Although treatment is aimed at managing or, hopefully, curing the underlying disease, medication may be needed to try to stop or slow down the undesired weight loss.

Mirataz is a topical ointment that you apply to the inside (non-hairy) part of your cat’s ear. The drug is absorbed transdermally, meaning through the skin. The active ingredient in Mirataz is mirtazapine. Scientists don’t know exactly how it works to induce weight gain, but it’s likely due to multiple factors.

You apply a 1.5-inch ribbon of Mirataz ointment topically once daily for 14 days, switching between the left and right ears. Your veterinarian or trained veterinary staff will show you how to apply it. You can also refer to the drug’s carton for pictures and a measuring ruler. On the first day, apply the ointment to the inside of your cat’s left ear. On the second day, apply it to inside of your cat’s right ear, and then keep alternating ears for the 2 weeks of treatment.

When applying Mirataz, wear disposable gloves so you don’t accidentally get some of the ointment on your skin. Throw out the gloves after each use and then wash your hands with soap and water. Also, separate your cat from people or other animals in your household for 2 hours after each dose. This prevents household members from being accidentally exposed to the ointment and allows time for the drug to be absorbed by your cat.

You may see skin reactions on your cat’s ears in the area where you apply the ointment (redness is the most frequent reaction). Your cat may vocalize more than normal and become hyperactive. Vomiting is also a side effect in some cats receiving Mirataz, likely due to them grooming the ointment off their ears and ingesting the drug.

Veterinarians should use caution when prescribing Mirataz for cats with liver or kidney disease. The drug may cause increased liver values. Cats with kidney disease may be slower at clearing Mirataz from their system, resulting in higher drug levels in the body.

After you stop giving Mirataz, your cat may have a decreased appetite. If your cat stops eating most of his food for several days or doesn’t eat anything for more than 2 days, contact your veterinarian.

Compounded Products Made from Bulk Mirtazapine are Unapproved

Many drug compounding pharmacies offer transdermal mirtazapine products for cats. These products are legal as long as FDA-approved Mirataz is the source of the mirtazapine in the compounded product. (Drug compounding is the process of combining, mixing, or altering ingredients to create a medication tailored to the needs of an individual animal or a small group of animals.)

However, some drug compounding pharmacies make transdermal mirtazapine products for cats that are compounded from bulk mirtazapine. These products aren’t legal and FDA considers them to be unapproved animal drugs. They haven’t been reviewed by FDA to make sure they are safe, effective, properly manufactured, and adequately labeled and packaged.

Mirtazapine Products Approved for People

Several mirtazapine products are FDA-approved for people, which veterinarians can legally use in cats in an extra-label manner. However, the human-approved mirtazapine products haven't been proven to be safe and effective in cats. Also, the labeling includes information on how to use the drug in people, not in cats. (Extra-label means using an approved human or animal drug in a way that isn’t listed on the drug’s labeling. FDA hasn’t reviewed the safety and effectiveness of the drug for that particular use. Extra-label use is sometimes called "off-label" because the use isn't on the label.)

Another concern with using human-approved mirtazapine products in cats is the difference in dose. The smallest strength for people is 15 mg while the typical dose for cats is 2 mg. It’s very difficult to cut a 15-mg tablet for people into the appropriate dose for a cat.

With the approval of Mirataz, veterinarians can now prescribe an approved mirtazapine product with known safety and effectiveness in cats rather than rely on unapproved compounded products or products intended for people.

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Semintra for Controlling High Blood Pressure in Cats

You take your 15-year-old cat Bailey to the veterinarian for her annual exam, which includes a routine check of blood pressure. The veterinarian explains that Bailey has high blood pressure (hypertension) and prescribes Semintra.

Kidney disease and hyperthyroidism (elevated thyroid hormone levels) are the two most common causes of high blood pressure in cats. Certain heart diseases can also cause high blood pressure in cats. You should talk with your veterinarian about which tests are most appropriate to determine the cause of your cat’s high blood pressure. Sometimes, no underlying cause is identified. When left untreated, high blood pressure can damage your cat’s eyes, kidneys, heart, and brain and central nervous system.

Semintra is the first FDA-approved drug to control high blood pressure in cats. The active ingredient in Semintra is telmisartan and it lowers blood pressure by relaxing blood vessels.

Semintra is an oral solution that you give either directly into your cat’s mouth or on top of a small amount of food. Don’t mix the solution into the food. Initially, you give the drug twice a day for 14 days and then once a day. To prevent giving an incorrect dose, only use the special dosing syringe provided in the package. The dosing syringe fits into the bottle opening and has clear marks for measuring the dose.

Your veterinarian should check your cat’s blood pressure regularly after starting Semintra and adjust the dose as needed to keep your cat’s blood pressure at the best level. Veterinarians should monitor cats with kidney disease early in treatment for potential worsening of their kidney values. When starting treatment, veterinarians should monitor all cats for anemia (low level of red blood cells) and a decreased appetite resulting in weight loss. Other common side effects of Semintra include vomiting, diarrhea, and a decreased activity level.

Pregnant women should avid any contact with Semintra because other similar drugs have been found to harm the unborn baby during pregnancy.

Your veterinarian should give you a Client Information Sheet every time you receive a prescription for Semintra, whether it’s the first time your cat is receiving the drug or it’s the 15th refill. The Client Information Sheet for Semintra is written specifically for cat owners, in a user-friendly, question-and-answer format. The handout gives you detailed information about Semintra and its side effects, helping you use the drug as safely and effectively as possible in your cat.

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Reporting Problems

FDA encourages you to call your veterinarian if you think your cat is having a side effect from Mirataz or Semintra. A side effect associated with a drug is called an adverse event. Adverse events also include a lack of effectiveness (the drug doesn’t do what it’s supposed to do) and reactions in people who handle the drug. Call your healthcare provider if you have a reaction to Mirataz or Semintra.

FDA also encourages you to work with your veterinarian to report any adverse event—in either pets or people—associated with Mirataz or Semintra or any product defect such as a problem with the dosing syringe for Semintra or the drug is off-color. How to Report Animal Drug and Device Side Effects and Product Problems.

Remember to keep Mirataz and Semintra in a secure location out of reach of children, dogs, cats, and other animals to prevent accidental ingestion or overdose.

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Benefit of FDA Approval

Knowing a drug is safe, effective, and high-quality is the benefit of FDA approval. During the approval process for an animal drug, the agency evaluates information submitted by the drug company to make sure the drug is safe and effective for its intended use and that the drug is properly manufactured and adequately labeled and packaged.

FDA-approved Mirataz and Semintra have both been shown to be safe and effective in cats when used according to the directions on the label. Each drug’s label provides dosing and safety information specific to cats. Both drugs are also properly manufactured and adequately packaged.

With Sunny’s weight back on track and Bailey’s high blood pressure under control, their 4 a.m. wake-up calls for playtime are back. Now if only they would wait until 7 a.m. to meow in your ear and bat you on the head…!

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Resources for You

Dear Veterinarian Letter – Mirataz (mirtazapine transdermal ointment)

For More Information

See Animal Drugs @ FDA for more information about Mirataz and Semintra.

Contact FDA’s Center for Veterinary Medicine at either AskCVM@fda.hhs.gov or 240-402-7002.

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