[Role of drug assays in the treatment of epileptic patients].

Drug assays play an important role in the control of antiepileptic treatment because the relationship between the serum concentration of an active drug and its therapeutic effects and side-effects is closer than between dose and effect. Bioavailability, protein binding and drug elimination are subject to inter- and intraindividual variations. However, it is important to remember that the optimal therapeutic ranges reported for serum levels are only a guideline to drug therapy. It is the patient who must be treated and not the serum level.