Phenytoin, Serum or Plasma

Phenytoin is useful in generalized tonic-clonic, complex partial, and simple partial seizures and frequently is chosen for initial therapy, particularly in adults. Because of phenytoin's potential adverse reactions (hirsutism, gingival hyperplasia, coarsening of facial features), other antiepileptic drugs are often prescribed for infants and young children. Phenytoin is commonly given with phenobarbital, primidone, carbamazepine, or valproate when monotherapy fails. It is ineffective in absence, myoclonic, and atonic seizures and is not recommended for the treatment of infantile spasms, Lennox-Gastaut syndrome, and epileptic syndromes in older children and adolescents when absence seizures or myoclonus is present. Intravenous phenytoin sodium is effective for status epilepticus and can be used as the initial drug to manage recurrent seizures if they are widely spaced. This drug also may prevent seizures initially in high-risk patients with head trauma. Phenytoin has been advocated for many other disorders, but conclusive evidence of effectiveness is inadequate for most proposed indications.