[Pharmacokinetics of psychotropic drugs: importance in psychiatric practice]

The clinical importance of pharmacokinetic studies of psychotropic drugs is described. First, definitions of the main pharmacokinetic parameters which allow accurate evaluation of the fate of a drug in the organism are given. Secondly, two important points are considered: the variability of drug plasma concentrations from one patient to another with identical doses makes "standard dosages" worthless; current data evidences correlations between the therapeutic effect of a drug and it's plasma concentrations. Clinical implications of the above points are as follows: adjustment and prediction of dosages; definition of rational precepts of prescription; definition of principles for monitoring treatment. These implications are exemplified by clinical cases reported in the medical literature or seen in the department of psychiatry at the university hospital in Besançon.