The relevance of clinical pharmacokinetics and therapeutic drug monitoring: anticonvulsant mood stabilizers and antipsychotics.

This review considers the relevance of clinical pharmacokinetics and the role of therapeutic drug monitoring (TDM) for two classes of psychotropics: the anticonvulsant mood stabilizers and the antipsychotics. In the first class, carbamazepine is a potent stimulator of the hepatic microsomal enzyme oxidation system, while valproic acid inhibits these same enzymes. In addition, these agents' highly protein-bound status can alter the availability of the free fraction of other coadministered agents. For both reasons, TDM during their administration may be useful. The antipsychotics demonstrate wide variations in absorption, first-pass effect, and volume of distribution among individuals. Depot antipsychotics have long elimination half-lives, often taking months to achieve steady-state levels or, conversely, to complete their washout. While correlations between antipsychotic plasma concentrations and clinical response are still under study, there are specific instances when TDM can be used to maximize clinical benefit and/or avoid adverse events.