Therapeutic drug monitoring for antidepressant drug treatment.

The aim of antidepressant drug treatment is to produce remission without causing adverse effects during the acute phase of the illness and to prevent relapses or recurrences during continuation or maintenance therapy. To achieve these goals, drug choice and dosage must be optimized for each patient individually. Therapeutic drug monitoring (TDM), which is based on the assumption that clinical effects correlate better with blood levels than doses, can be helpful. When using tricyclic antidepressant drugs TDM enhances safety and efficacy. For newer antidepressant drugs, however, it is a matter of debate to which extend TDM can have beneficial effects. For many antidepressants there exist carefully designed studies concerning the relationship between plasma concentration and clinical effects that allow the definition of recommended therapeutic ranges of the plasma concentration. In some drugs however, concentration-effect studies are lacking so far, but target ranges resulting from clinically relevant plasma concentrations or from pharmacokinetic studies could be provided. During the last years, knowledge on therapeutic references ranges in blood towards TDM guided treatment has markedly improved for new antidepressant drugs, and many specific indications have been defined for useful TDM. Recently published guidelines describe the best practice of TDM for neuropsychiatric drugs. The aim of this review is to summarize the current status of TDM for antidepressant drugs and discuss the literature with regard to response optimization, pharmacovigilance and economic benefits and with regard to needs for further research.