Are you certain this is epilepsy? Has he been treated for e cuniculi? E cuniculi is as a rule the first thing you suspect when a bunny has seizures. It’s a microscopic parasite. It tend to attack the brain and/or the kidneys and/or the heart. Loss of litter-box habits/bladder control is another symptom commonly seen with e cuniculi.
Epilepsy does occur in rabbits but it’s much more rare. E cuniculi is a parasite up to 80% of rabbits are believed to be carriers of. Standard treatment is dewormer called Panacur (fenbendazole) for 28 days.
Diazepam is a bensodiazepine. It’s given to alleviate seizures of any kind, not specifically epileptic seizures. Most commonly it’s used as a tranqulizer/sedative. In rare cases paradox reactions are seen, meaning the patient gets agitated and excited, an ongoing seizure can get worse, muscle cramps can occur – the exact oposite of how the drug is supposed to work.