Fosphenytoin is an antiepileptic agent used for the management of generalized convulsive status epilepticus and prevention and treatment of seizures occurring during neurosurgery. It can be found under the brand names Cerebyx and Sesquient. Fosphenytoin is a water-soluble phenytoin prodrug used only in hospitals for the treatment of epileptic seizures. It works by slowing down impulses in the brain that cause seizures. Its main mechanism is to block frequency-dependent, use-dependent and voltage-dependent neuronal sodium channels, and therefore limit repetitive firing of action potentials. Fosphenytoin is a prodrug of phenytoin and accordingly, its anticonvulsant effects are attributable to phenytoin. Fosphenytion is metabolized in the liver by CYP 2C9 enzymes. Phenytoin acts on sodium channels on the neuronal cell membrane, limiting the spread of seizure activity and reducing seizure propagation. By promoting sodium efflux from neurons, phenytoin 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 post-tetanic potentiation at synapses. Loss of post-tetanic potentiation prevents cortical seizure foci from detonating adjacent cortical areas. Some side effects of using fosphenytoin may include itching, burning, confusion, and loss of coordination.

Fosphenytoin Pathway (New) References