[Value of plasma assays of psychotropic drugs]

An increased use of determinations of psychotropic drug levels has been noted during recent years. The contribution of "biological techniques" has led to a change in the relationship between physician and patient by rationalizing medical prescription and by augmenting the medical nature of this relationship. Follow-up of plasma levels is of interest for psychotropic drugs having therapeutic and (or) side effects that are linked to blood concentrations. Such drugs include the imipraminic antidepressants and regulators of thymic function. There is no consensus concerning the benzodiazepines and neuroleptic drugs. Their clinical effect does not seem to be strictly linked to plasma levels and the range of dosages is greater. Such determinations have proved to be particularly interesting in "resistant" cases, in surveillance of drug interactions and to evaluate treatment compliance.