Idiopathic epilepsy is the most common neurologic disorder affecting canines and is diagnosed in about 5 percent of dogs. On January 14, 2021, the United States Food and Drug Administration (FDA) granted conditional approval to a new prescription drug, KBroVet-CA1, to treat this problematic disease. KBroVet-CA1 is the first conditionally approved treatment for idiopathic canine epilepsy under the reauthorized 2018 FDA’s Animal Drug User Fee Act. Developed by Pegasus Laboratories Inc., KBroVet-CA1 is a liver-flavored potassium bromide chewable tablet.
Conditional approval for veterinary drugs
Conditional approval is an option for drugs intended for use in minor species, or minor uses in major species. For conditional approval, a drug company must exhibit that the drug is safe when used according to label directions, and has a “reasonable expectation of effectiveness.” Full approval requires substantial evidence toward effectiveness standards. During the conditional approval period, the drug company can legally sell and promote the veterinary drug for its labeled uses, while continuing to collect data on the drug’s effectiveness. Initial conditional approval is valid for one year and can be renewed for up to four more years, so long as the company demonstrates progress toward proving the substantial evidence required for full approval. Drugs that are conditionally approved must include “Conditionally approved by FDA pending a full demonstration of effectiveness” on the label.
Potassium bromide’s role in treating canine idiopathic epilepsy
First used in 1857 to treat epilepsy in people, potassium bromide has a long history of helping seizure patients. The anticonvulsant is no longer commonly used to treat humans but used as a primary treatment, or in conjunction with another drug, to help decrease seizure frequency in epileptic dogs. Potassium bromide is a halide salt that stabilizes neurons when the drug passes through neuronal channels by hyperpolarizing neuronal membranes and has been shown to decrease seizure frequency in 72 to 74 percent of epileptic dogs. Despite potassium bromides’ historical usefulness, no veterinary drug company had applied for approval before the 2018 authority.
KBroVet-CA1’s role in treating canine idiopathic epilepsy
KBroVet-CA1 is a chicken-liver-flavored chewable tablet specifically formulated for dogs. The drug is administered once daily and currently is available in a 60-count bottle, although 180-count bottles should be available by summer 2021. Tablets are available in 250 mg and 500 mg formulations. KBroVet-CA1 has a 21-day half-life, ensuring minimal drug concentration fluctuations should an owner miss a dose. The drug is excreted through glomerular filtration.
KBroVet-CA1 received conditional approval by exhibiting a reasonable efficacy expectation during a retrospective study. Fifty-one client-owned epileptic dogs were given potassium bromide as a sole treatment to control their seizures for at least 60 days. In each case, seizure counts, seizure event days per month, and seizure severity scores were evaluated. The study showed:
Potential side effects seen in dogs taking KBroVet-CA1
The retrospective study also documented any clinical abnormalities witnessed during the 60-day trial. The most common adverse reactions seen in dogs taking potassium bromide include:
Other possible side effects include constipation, decreased appetite, polyuria, and polydipsia. When used as an adjunct therapy to another antiepileptic drug, such as phenobarbital, reversible neurologic abnormalities were most commonly seen, including:
Older dogs may be more susceptible to adverse reactions. Dogs affected by decreased renal function may be predisposed to bromide toxicosis. Dogs receiving KBroVet-CA1 should be carefully monitored, especially when changing diets, receiving chloride-containing intravenous fluids, and receiving other medications. Dogs who are affected by any condition that makes maintaining electrolyte balance difficult need close evaluation if receiving KBro-VetCA1. The drug's safety for breeding, pregnant, or lactating dogs has not been evaluated, or for neonates and puppies. Ataxia, diarrhea, hematochezia, excessive salivation, shivering, skin lesions, stupor progressing to coma, and death have been reported in dogs receiving 200 to 500 mg/kg a day for 4 to 26 weeks.
Veterinarians have been using potassium bromide for centuries to help manage their canine patients’ seizures. KBro-VetCA1 offers a convenient delivery method to treat dogs affected by idiopathic epilepsy, but, as with any drug, patients receiving KBro-VetCA1 should be carefully monitored for side effects.
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