Can pharmacokinetic variability be controlled for the patient's benefit? The place of TDM for new AEDs

The aim of this brief communication is to update our recent review on therapeutic drug monitoring (TDM) of the newer antiepileptic drugs (AEDs). The potential value of TDM is discussed in relation to their mode of action and their pharmacokinetic properties. Data on the relationships between serum concentrations and clinical efficacy are limited, and few studies have been designed primarily to study these relationships. As yet there,are no generally accepted target ranges for any of the new AEDs. For most drugs a wide range in serum concentration is associated with clinical efficacy, and there is a considerable overlap in serum concentrations related to toxicity and lack of clinical efficacy. Although the available documentation is clearly insufficient, the pharmacological proper-ties of some of the drugs suggest that they may be suitable candidates for TDM. The primary role of TDM for both the newer and established AEDs is to identify an individual's optimum concentration and thus establish a reference value in that patient.