Established antiepileptic drugs.

The major established drugs used in the management of epilepsy are carbamazepine, valproic acid, phenytoin, phenobarbital, primidone, ethosuximide and benzodiazepine drugs. Carbamazepine and phenytoin are used mainly in the treatment of partial seizures and primarily or secondarily generalized tonic-clonic seizures. Valproic acid is effective against all types of seizures, but it is used most extensively in the management of generalized epilepsies. Ethosuximide is effective against absence seizures. Phenobarbital and primidone are effective against all types of seizures (except for absences) although they are less commonly used because of their sedative properties and adverse effects on cognition. Benzodiazepines are most valuable in the treatment of status epilepticus, but their long-term use is often associated with undesirable sedation and development of tolerance to their antiepileptic effect. Irrespective of the drug used, optimal clinical management requires individualization of dosage and dosing schedules based on careful evaluation of clinical response and sound knowledge of the pharmacokinetics and interaction potential of the individual compounds. Monitoring serum drug concentrations may provide a useful guide to dosage adjustments, particularly in the case of phenytoin, which shows dose-dependent kinetics within the therapeutic dosage range.