FDA Alert Isoxazoline Class of Drugs

Recently the FDA posted an alert that the flea and tick medications in the isoxazoline class are now carrying a possible seizure risk in dogs and ataxia in cats. These are FDA approved products that are safe and effective for the majority of healthy pets. There have been post-approval studies in Credelio, Simparico, Nexgard, and Bravecto which are all in the isoxazoline class of drugs. We at AHNA have been aware of the possibility of rare side effects listed in the studies of this class of drugs. We have used Nexgard and Bravecto in not only our patients but our own cats and dogs for many years and have monitored for reactions. We have not had any adverse events of seizures, muscle tremors or ataxia. ​ We do not recommend these products in pets with neurological disorders. Our veterinarians consider the pet's health, medical history, and lifestyle when recommending medications for parasite control for your cat or dog. If your pet experiences seizures, neurological problems or muscle tremors, please contact us. If you have questions or concerns, we are happy to answer them.

FDA Alert isoxazoline class of Drugs: FACT SHEET

From Merck Animal Health

Merck Animal Health, the manufacturer of the Bravecto portfolio of products, remains confident in the safety and efficacy of Bravecto, which has been established through comprehensive clinical research in more than 170 studies. Nothing has changed about the Bravecto product.

The current FDA communication is based on information gathered on the isoxazoline class as a whole and therefore applies to all products in the class, which includes Bravecto.

After over three years of surveillance of more than 80 million Bravecto doses distributed in 85 countries, the overall worldwide reporting rate for neurological signs, including seizures, remains classified as very rare.  Very rare is defined by international regulatory authorities as less than 1 in 10,000 incidences.

Every molecule is unique, even within a class, and each has its own safety profile. This is why it’s important for all pet owners to speak to their veterinarian before making a decision about flea and tick control products for their dog.

Nothing is more important to Merck Animal Health than the safety and efficacy of our products and the well-being of animals. We encourage all pet owners to speak to their veterinarian before making a decision about flea and tick control products. More than just a nuisance, fleas and ticks transmit disease and pose animal and human health risks. It is critical to protect pets from these parasites.

Reactive statement

As part of its regular monitoring of all pharmaceutical products, the U.S. Food and Drug Administration (FDA) conducted a review of the isoxazoline class of parasiticides. As part of this review, the FDA has issued a drug safety communication and has requested updates to the prescribing information of all medicines in the isoxazoline class – including BRAVECTO (fluralaner) – to include information about possible neurologic adverse reactions in the precautions section.

Merck Animal Health remains confident in the safety and efficacy profile of Bravecto, which has been established through comprehensive clinical research in more than 170 studies. After three years of post-marketing surveillance of more than 80 million Bravecto doses distributed in 85 countries, the overall worldwide reporting rate for neurological signs, including seizures, remains classified as very rare.

Nothing is more important to Merck Animal Health than the safety and efficacy of our products and the well-being of animals. We encourage all pet owners to speak to their veterinarian before making a decision about flea and tick control products. More than just a nuisance, fleas and ticks transmit disease and pose animal and human health risks. It is critical to protect pets from these parasites.