Imepitoin (INNTooltip International Nonproprietary Name), sold under the brand name Pexion, is an anticonvulsant which is used in veterinary medicine in Europe to treat epilepsy in dogs.

[1][2] It was originally developed to treat epilepsy in humans, but clinical trials were terminated upon findings of unfavorable metabolic differences in smokers and non-smokers.

[1][2] Imepitoin acts as a low-affinity (4,350–5,140 nM; relative to Ki = 6.8 nM for diazepam and Ki = 1.7 nM for clonazepam) partial agonist of the benzodiazepine site of the GABAA receptor (up to 12–21% of the maximal potentiation of diazepam, a full agonist of this site).

[1] The drug also dose-dependently blocks voltage-gated calcium channels.

[3] It is not a benzodiazepine; instead, it is an imidazolone, and bears some structural similarities to hydantoin anticonvulsants like ethotoin and phenytoin.