Mephenytoin is a hydantoin-derivative anticonvulsant used to control various partial seizures. It is generally reserved for treatment of individuals refractory to less toxic agents. Mephenytoin and oxazolidinedione derivatives are associated with higher incidences of blood dyscrasias compared to other anticonvulsants. As such, these agents should not be used concurrently.
Indication
For the treatment of refractory partial epilepsy.
Pharmacology
Mephenytoin is an antiepileptic drug which can be useful in the treatment of epilepsy. The primary site of action appears to be the motor cortex where spread of seizure activity is inhibited. Possibly by promoting sodium efflux from neurons, mephenytoin tends to stabilize the threshold against hyperexcitability caused by excessive stimulation or environmental changes capable of reducing membrane sodium gradient. This includes the reduction of posttetanic potentiation at synapses. Loss of posttetanic potentiation prevents cortical seizure foci from detonating adjacent cortical areas. Mephenytoin reduces the maximal activity of brain stem centers responsible for the tonic phase of tonic-clonic (grand mal) seizures.
An imidazolidine-2,4-dione (hydantoin) in which the imidazolidine nucleus carries a methyl group at N-3 and has ethyl and phenyl substituents at C-5. An anticonvulsant, it is no longer available in the USA or the UK but is still studied largely because of its interesting hydroxylation polymorphism.
有害性 (Xn)