Lack of correlation between the anaesthetic and anti-convulsant potencies of althesin, ketamine and methohexitone.

Using Sprague-Dawley rats, the anti-convulsant potencies of Althesin, ketamine and methohexitone were determined for bicuculline-and strychnine-induced seizures and compared with their effects on hyperbaric seizures. All three anaesthetics protected against both types of chemical convulsants; the degree of protection varied from 34 to 151%, with Althesin being the most effective. However, there was no correlation between their anti-convulsant and anaesthetic potencies, and no relationship between the effects on chemical convulsions and the interactions of the same agents with hyperbaric convulsions. These data suggest that the order of anti-convulsant potencies at equivalent anaesthetic concentration is Althesin much greater than ketamine = methohexitone, and that neither bicuculline-nor strychnine-induced seizures are a good model for hyperbaric convulsions.