Phenobarbital vs Imepitoin
In case you haven't been an avid reader of novel anti-convulsant drugs over the past few years, please allow me to quickly introduce to you the newest drug hitting Europe. Imepitoin (Im-ep-I-TOE-in) is the hottest new drug that folks were (are?) pretty excited about. It performed pretty well in clinical trials, and seemed to be well tolerated by dogs. It is not available in the States.
The set up
A recent study out of England in The Veterinary Journal (2019:249:53-57) evaluated seizure frequency (before treatment compared to after treatment) and the development of cluster seizures in a prospective clinical trial of naive dogs with confirmed idiopathic epilepsy. (I use the word confirmed softly because, of course, this is a diagnosis of exclusion by blood work, MRI and spinal tap. All dogs had normal testing in this study.) The dogs were naive because they had never received any anti-convulsant drugs. Thirty-one dogs received imepitoin; 30 dogs received phenobarbital. The phenobarbital dogs had a higher pre-treatment seizure frequency, but no dogs had observed cluster seizures at the start of the study. (This is key!)
Spoiler alert - Phenobarbital won!
The dogs in this study had a significantly higher reduction in seizure frequency (less seizures per month POST treatment, compared to PRE treatment), and developed cluster seizures less frequently and later in the course of their disease.
Other comments:
The dose for phenobarbital was between 2.5-5 mg/kg per os q12h.
They tracked serum concentrations and seizure frequency and adjusted doses frequently. We need to be better at tracking serum concentrations in our patients receiving phenobarbital!
Reported efficacy of phenobarbital for controlling seizures using is between 60-93% in dogs on monotherapy. (This is a summary of the literature)
Transient self-limiting adverse effects were reported as follows in this study: Sedation 16/30 (53%); Ataxia 16/30 (53%), Polyphasia 7/30 (23%), polydipsia 7/30 (23%); polyuria 6/30 (20%), aggression 0/30. No dogs in the phenobarbital group developed severe enough adverse effects that the treatment was withdrawn. Take this information to clients! When the internet scares us, or clients, away from phenobarbital here is the actual data! We have all treated the occasional dog with the exaggerated response to an anti-convulsant drug; try not to loose sight of the group data.
I hope this bit of information is useful and helpful as you work to help pets with seizures.
One final bit of news.... coming soon I will be offering vets digital access to the seizure questionnaire that I provide to owners prior to a seizure consultation. This form ensures pertinent information is gathered and can further direct the conversation, especially when time is limited. You'll be able to modify it to match your hospital stationery and add logos too!
Do you need help with seizure management? Please call or email me! You can use my online scheduler now to schedule telephone consults and VIDEO telemedicine consults too!