ZONISAMIDE FOR SEIZURES

Written by Dr. William Thomas, DVM, MS Dipl. ACVIM (Neurology)
University of Tennessee

From the annual ACVIM forum in Charlotte, NC:

Curtis Dewey presented an abstract on using zonisamide (Zonegran) in 12 dogs with epilepsy refractory to other drugs (mostly phenobarbital and bromide). Seven dogs (58%) had a decrease in the number of seizures after starting zonisamide, with a mean decrease in seizure frequency of 81%. In 8 of these dogs, it was possible with decrease the dose or withdraw concurrent anti-seizure drugs. Side effects were very mild.

Question on Zonegran for Dr. Thomas:

Zonegran caught my attention and I wondered how this AED is metabolized?

Dr. Thomas answer:

In the dog, zonisamide (Zonegran) we use 10 mg/kg every 12 hours and is metabolized by the liver, with an elimination half-life of 15 hours.

Zonisamide seems to be an effective "second-line" drug in dogs, based on limited clinical experience. It's elimination half-life is 15-20 hours in dogs, so it is usually given twice daily. It's expensive. So far, side effects in dogs seem rare.