Cites potential risk for seizures for some dogs, cats with products like Bravecto, NexGard, Simparica containing a form of the pesticide isoxazoline.
The U.S. Food and Drug Administration is alerting pet owners and veterinarians that certain FDA-approved pet and flea medications containing the pesticide isoxazoline have been found to carry a potential risk for seizures in dogs and cats.
The FDA said in its Sept. 20 alert that it is working with the manufacturers of the FDA-approved products that it said "continue to be safe and effective for the majority of animals" to include new label information to highlight what it called "neurologic events because these events were seen consistently across the isoxazoline class of products."
"Since these products have obtained their respective FDA approvals, data received by the agency as part of its routine post-marketing activities indicates that some animals receiving Bravecto, NexGard or Simparica have experienced adverse events such as muscle tremors, ataxia, and seizures," the FDA said.
"Another product in this class, Credelio, recently received FDA approval. These products are approved for the treatment and prevention of flea infestations, and the treatment and control of tick infestations."
NexGard (active ingredient afoxolaner) was approved in 2013 and said to be is for dogs and puppies eight weeks of age or older, weighing 4 pounds or more; Bravecto (fluralaner), in 2014 and is available for dogs and cats; and Simparica (sarolaner), in March 2016.
The manufacturer's website for Simparica says it is for "use only in dogs, 6 months of age and older" and notes it "may cause abnormal neurologic signs."
The statement from the FDA added that the FDA "is working with manufacturers of isoxazoline products to include new label information to highlight neurologic events because these events were seen consistently across the isoxazoline class of products."
"The FDA carefully reviewed studies and other data on Bravecto, Credelio, Nexgard and Simparica prior to approval, and these products continue to be safe and effective for the majority of animals," the FDA said.
"The agency is asking the manufacturers to make the changes to the product labeling in order to provide veterinarians and pet owners with the information they need to make treatment decisions for each pet on an individual basis."
It has issued a fact sheet for pet owners and veterinarians about the potential adverse effects.
"Although most dogs and cats haven't had neurologic adverse reactions," the sheet notes, "seizures may occur in animals without a prior history."
The FDA advises that veterinarians "use their specialized training to review their patients' medical histories and determine, in consultation with pet owners, whether a product in the isoxazoline class is appropriate for the pet."
The FDA said that while its scientists "carefully evaluate an animal drug prior to approval, there is the potential for new information to emerge after marketing, when the product is used in a much larger population."
"In the first three years after approval, the FDA pays particularly close attention to adverse event reports, looking for any safety information that may emerge," the FDA said.
It said it "encourages pet owners and veterinarians to report adverse drug events" to either the FDA or drug manufacturers.
The given contact numbers for the manufacturers are:
Merck Animal Health (Bravecto): 800-224-5318
Elanco Animal Health (Credelio): 888-545-5973
Merial (NexGard): 888-637-4251
Zoetis (Simparica): 888-963-8471
To report directly to the FDA, click on How to Report Animal Drug Side Effects and Product Problems.