Fluoxetine plasma levels and efficacy in Major Depressive Disorder

Introduction. A great interest has been called in clinical practice about the possibility of establishing the appropriate antidepressant medication regimen on the basis of plasmatic concentrations. Nevertheless any published studies have not reached concluding results. The present study attempts to correlate plasmatic levels of fluoxetine and norfluoxetine, its active metabolite, with short term clinical effectiveness in patients with Major Depressive Disorder (MDD). Material and method. Nine patients with MDD, of both sex, treated with fluoxetine 20 mg/day for the first time have been evaluated through Montgomery-Asberg Depression Rating Scale (MADRS), Raskin Depression Scale (RDS) and Covi Anxiety Scale (CAS). Psychopathological modifications as well as plasmatic levels of fluoxetine and norfluoxetine have been evaluated after 1 (T1) and 4 (T2) weeks of treatment. Results. Anxiety and depression resulted both significantly decreased at T1 and T2. A significant correlation between mean score of CAS and plasmatic levels of norfluoxetine was found. It suggests that the compound has effective action reducing anxiety. Conclusions. No evidence of significant correlation between plasmatic levels of fluoxetine and norfluoxetine and clinical improvement of depression was demonstrated.