Which medicines are covered in the warning?
Bravecto, Credelio, Nexgard, and Simparica are the FDA-approved drugs in the isoxazoline class. Those are the only drugs included in this warning. All of these medications are chewable tablets; folks who rely on spot-on pesticides such as Frontline or Advantage are 100 percent in the clear. There are also several brands of tablets that are not in the isoxazoline class, and therefore not included in this warning. Don’t assume this warning automatically means your pet is at risk, especially if they haven’t taken the four drugs listed above.
The alert comes after routine data collection revealed that some pets given isoxazoline class treatments “have experienced adverse events,” the FDA says.
The majority of the affected products are sold as flavored chews, NBC News reports. The labels of such products already include information about the risk of neurological side effects, the network reports.
Dogs and cats treated with certain flea and tick products might be at an increased risk for neurologic events including seizures, the U.S. Food and Drug Administration said Thursday.
Although most pets have not had adverse reactions with the treatments, some have had seizures without a prior history, the FDA said in a fact sheet for pet owners.
The treatments will soon “include new label information to highlight neurologic events because these events were seen consistently across the isoxazoline class of products,” the FDA says.
What does this warning actually mean?
The FDA’s warning does not mean your pet is going to have a seizure, even if they’re taking these drugs. According to the FDA, most dogs and cats do not have adverse reactions to isoxazoline. They “can and have been safely used in the majority of dogs and cats,” according to the agency’s statement. But because there have been reports of muscle tremors, ataxia (the loss of control of bodily movements), and seizures even in animals with no prior history of such problems, the agency will have manufacturers include warnings of these potential side-effects on drug packaging.
Seizures in Dogs – Causes, Diagnosis and Treatment | Southeast Veterinary Neurology
Four flea and tick products may cause seizures, tremors, and lost coordination in some cats and dogs.
Food and Drug Administration officials have received thousands of reports of adverse events connected with three products—Bravecto, Nexgard, and Simparica—containing drugs in the isoxazoline class. The agency approved a fourth product, Credelio, containing a drug in the class this year.
“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,” a Sept. 20 announcement states.
The agency has approved all four products since 2013 for treatment and prevention of flea infestations and treatment and control of tick infestations. They are safe and effective for most pets, but veterinarians should use patient medical histories to decide whether isoxazoline-class drugs are appropriate, the announcement states.
Siobhan DeLancey, who is a spokeswoman for the FDA Center for Veterinary Medicine, said the agency has received about 5,400 reports of adverse events connected with the drugs.
She provided a statement that said agency officials are seeing reports of neurologic events at similar rates across the isoxazoline product class, when those reports are compared with sales data. But the agency is unable to compare among products because its impossible to know how many of the doses sold have been administered.
Researchers who conducted preapproval studies saw some of the neurologic signs, and some of the product labels already note that potential, DeLancey said. In the reports of adverse events since approval, some animals developed seizures with no known history of them.
Most of the reports involve dogs, but whether the risk is higher in dogs or cats is unknown. Only one of the products—Bravecto—is approved for use in cats.
FDA reports that summarize evidence used toward approval of the four products include descriptions of seizures, tremors, ataxia, and lethargy among a small number of dogs and ataxia in a few cats involved in clinical trials. Results of one trial for Simparica involving a small number of 8-week-old puppies, for example, indicated that those that received higher doses were more likely to have neurologic signs.