Therapy for canine idiopathic epilepsy receives FDA conditional approval

The FDA announced it has conditionally approved phenobarbital tablets (Fidoquel-CA1; Genus Lifesciences Inc.) to control seizures that are associated with idiopathic epilepsy in dogs. This product is the only phenobarbital tablets to receive FDA conditional approval for safety, quality manufacturing, and reasonable expectation of effectiveness.¹

Conditional FDA approval means that drug sponsors can legally market the product. The conditional approval is good for 1 year with the possibility of 4 renewals. However, the sponsor must demonstrate it is working toward collecting the remaining effectiveness data needed to receive full approval. If Genus Lifesciences Inc. does not maintain full approval within 5 years of the conditional approval, it will no longer be in effect.

Fidoquel-CA1 qualified for this conditional approval because of its intent to address serious or life-threatening diseases or conditions as well as the unpredictability of the seizures, and demonstration of effectiveness shown in complex or particularly challenging studies. This is possible due to Congress granting the FDA a limited expansion of the conditional approval pathway for particular animal drugs under the 2018 reauthorization of the FDA’s Animal Drug User Fee Act program.¹

Adverse reactions most commonly reported in studies with phenobarbital tablets are lethargy or sedation, ataxia, polyphagia, polyuria, and polydipsia, according to the FDA. These reactions tend to diminish within 10 days to 2 weeks after starting treatment because dogs usually develop tolerance. Overall, many of the adverse reactions are seen during longer-term administration and/or at high serum phenobarbital levels (> 35 mcg/mL). The FDA recommends that veterinarians closely monitor clinical signs in their patients because plasma levels only may not predict how each dog will tolerate the drug.³

According to the FDA, historically unapproved phenobarbital tablets for humans were used to control seizures in dogs.¹ Then in 2021, the agency conditionally approved potassium bromide chewable tables (KBroVet-CA1; Pegasus Laboratories). This drug stabilizes neurons in the dog’s central nervous system to reduce the chances of having a seizure.²

References

1. FDA Conditionally Approves Phenobarbital Tablets to Control Seizures in Dogs with Idiopathic Epilepsy. News release. U.S. Food and Drug Administration. September 6, 2023. September 6, 2023. https://www.fda.gov/animal-veterinary/cvm-updates/fda-conditionally-approves-phenobarbital-tablets-control-seizures-dogs-idiopathic-epilepsy?utm_medium=email&utm_source=govdelivery
2. FDA Grants First Conditional Approval Under Expanded Authority to Control Seizures in Dogs with Idiopathic Epilepsy. News release. U.S. Food and Drug Administration. January 14, 2023. Accessed September, 6, 2023. https://www.fda.gov/news-events/press-announcements/fda-grants-first-conditional-approval-under-expanded-authority-control-seizures-dogs-idiopathic
3. Freedom of information summary. FDA. September 6, 2023. Accessed September 6, 2023. https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/14500