Abstract
Introduction The evaluation of plasma levels of antidepressants may improve the treatment outcome.
The aim was to verify adherence and adequacy of administered doses of antidepressants
among patients hospitalized for inadequate outpatient therapeutic response.
Methods Selective serotonin reuptake inhibitors or venlafaxine plasma levels were assessed
on the first day of hospitalization and after 3 days of controlled administration.
The patients were considered adherent if the plasma level on admission was within
the interval of the minimum and maximum plasma level on the fourth day, expanded by
30%. The adequacy of antidepressant doses used during the outpatient treatment was
assessed by comparing the plasma level on the fourth day with the therapeutic reference
range.
Results Out of 83 patients, 52 (62.7%) were adherent. The plasma levels of antidepressants
on the fourth day were found to be within the therapeutic reference range in 35 (43.2%)
patients. The same number manifested levels below the therapeutic reference range.
In 11 (13.6%) patients, the levels were higher than recommended. No significant difference
in rate of adherence was found among individual antidepressants.
Conclusion The results show that antidepressant nonresponders are frequently under-dosed or
nonadherent.
Key words
adherence - depression - antidepressants - plasma levels - therapeutic drug monitoring
