Therapeutic drug monitoring of selective serotonin reuptake inhibitors influences clinical dosing strategies and reduces drug costs in depressed elderly patients

Objective: This study was initiated in order to describe and evaluate the effects of a therapeutic drug monitoring (TDM) routine of selective serotonin reuptake inhibitors (SSRIs) on treatment strategies and drug costs in depressed elderly patients. Method: Blood samples were drawn from elderly depressed patients and analysed for steady-state trough serum concentrations of citalopram (n = 48), paroxetine (n = 48) or sertraline (n = 39). A global efficacy evaluation was made at baseline and after 6-9 months. Antidepressant drug costs before and after TDM were estimated. Results: Eight samples were excluded due to technical problems or noncompliance. In 65 of the 127 (51.2%) remaining cases, the treatment strategy was changed according to the TDM outcome, in most a reduction of the prescribed dose. Bioanalytical TDM costs included the antidepressant drug costs after TDM were reduced by 10.2%. Conclusion: The results support the utility of TDM in the search for the individual minimum effective SSRI dose in the elderly.