The US Food and Commodities Authority, FDA, states in a message that pet owners should be alert to anti-fleas and tick-based pesticides based on isoxazoline. This active substance is mainly used in the chewable tablets that protects the dog for months against fleas, ticks and lice.
The most famous products from this group are Bravecto, Simparica and Nexgard, but recently a new product was launched based on isoxazoline: Credelio. The products have been associated with neurological problems including seizures, ataxia and muscle tremors.
Credelio is only recently admitted to the American market. However, the FDA emphasizes that the news has no consequences. The new insights into isoxazoline stem from regular studies and reports of side effects from veterinarians and pet owners. In a press release, the FDA reports that "they have received indications that some animals that were given Bravecto, Simparica or Nexgard suffered from side effects, including muscle tremors, ataxia and seizures."
The FDA then reports that the aforementioned drugs have been thoroughly investigated before being admitted to the US market and have been tested for efficacy and safety. According to them, nothing changes to the information provided at the time that the products are effective and safe for a majority of the animals to which it is administered.
There is therefore no question of the products being withdrawn. The FDA does enter into discussions with the manufacturers and wants the product information to be supplemented with a warning for these side effects.
“The agency is asking manufacturers to supplement the package leaflet so that veterinarians and pet owners can make a balanced choice for flea and tick treatment based on the individual. Veterinarians will have to use their knowledge and expertise to give correct advice for products based on isoxazoline, depending on the patient's medical history. "
The FDA also admits that after authorization of a product, side effects can be found that were unknown at that time. That is why they pay extra attention in the first three years after a product is admitted to reports of possible side effects. This information is received through vets, pet owners, new scientific studies and reports from manufacturers.
Finally, the FDA has announced that it is monitoring products well and is encouraging pet owners and veterinarians to report possible side effects. This can be done by reporting to the manufacturer, who is obliged to forward this to the FDA.
In addition, pet owners and veterinarians can also report a report directly to the FDA.
Already in 2017, the European Medicine Agency, the European medicine watchdog, called on manufacturers to modify their package leaflets with similar information. Also with EMA, so many side effects were reported that an additional investigation was started. Based on this, EMA decided that it was necessary to supplement the package leaflet with a warning for neurological problems, including seizures and ataxia. The English-language product information from Bravecto now contains the warning that caution is advised in animals that are familiar with epileptic seizures.