Therapeutic drug monitoring (TDM) of antidepressants provides the possibility of optimizing
psychopharmacotherapy. Based on individual indications, particularly for the classical
tricyclic antidepressants there is sufficient evidence of the benefit of TDM, whereas
for the newer compounds the database is more scarce. In the present investigation,
the application of TDM under naturalistic clinical conditions as well as its consequences
for the dosing of antidepressants and the length of stay in hospital was analyzed
retrospectively in psychiatric inpatients. In a pilot phase, 157 patients treated
with amitriptyline or sertraline were evaluated. For each patient, the first and the
last blood sample taken during the stay in hospital were considered. In patients treated
with amitripyline dose adjustments during the course of treatment were clearly more
frequent compared to patients treated with sertraline. In order to prove if the TDM
results were considered for dosing, the data were analyzed separately for subgroups,
where the first blood levels were below, above and within the therapeutic range, respectively.
For those patients revealing optimum blood levels already for the first blood sample,
there was no significant difference between the first and last values. In contrast,
if the first blood concentrations were below and above, respectively, the therapeutic
range, the second values were significantly higher and lower, respectively, compared
to the first values. For both drugs, no significant correlation was found between
TDM results and length of stay. In conclusion, based on these preliminary data, for
both antidepressants it could be shown that TDM results were used for drug dosing,
even though this was not reflected by an increased efficacy measured by shortening
of the length of stay. However, lack of significance can possibly be put down to the
small sample size. Currently, a more detailed analysis is ongoing in a larger sample
of patients considering all blood samples taken during treatment.
