The most commonly prescribed anti-seizure medicine for cats is phenobarbital. This drug has proven to be effective for cats, and is generally considered safe. If your cat is not able to tolerate phenobarbital, your vet may prescribe diazepam (valium).
As compared to dogs, seizures in cats are rare. After first determining the cause of the seizures by a veterinarian experienced in seizure control, the most common medication is phenobarbitol. Diazepam is also used but can cause liver problems. Careful monitoring is necessary.
Phenobarb is the most common medication used. Also sometimes used are Mysoline, Dilantin, valium and Neurontin to name a few. Accupuncture can also be effective. Natural or homeopathetic medications are also available and have been shown to be very effective without the side effects as with other vet prescribed medications.
Phenobarbital is the primary choice, diazepam is used for cats that don't tolerate that well. There are MANY causes for seizures, and they are often controlled by diet or natural means. You need to know his diagnosis and do research from there. Potassium bromide is starting to be used again.