Therapeutic drug monitoring: clues from escitalopram

Introduction: Therapeutic Drug Monitoring is the measurement of a specific drug serum concentration to ensure that appropriate drugs levels are maintained. For every drug it is possible to delineate a specific “therapeutic index”, above which significant side effects could occurrent. In psychiatry the issue is still controversial. ESCITALOPRAM: escitalopram, the (S)-enantiomer of the racemic selective serotonin reuptake inhibitor antidepressant citalopram, is an effective and well tolerated medication in the treatment of MDD (Major Depressive Disorder). In the dose-range of 10 to 30 mg/day pharmacokinetics (PK) are linear and dose-proportional. After oral administration steady-state concentrations are achieved within 7 – 10 days. Despite inter and intra-individual and overall pharmacokinetic variability, the therapeutic index – according with the AGNP-TDM – ranges between 15 – 80 ng/ml. Methods: 20 out-patients were evaluated with SCID-I, HAM-D at baseline and at 4 weeks. After diagnostic validation for MDD they were treated with escitalopram. At steady-state blood samples were collected and escitalopram serum concentrations measured. Results: in all the examples it was possible to optimize the clinical practice taking into account the escitalopram serum concentrations in relation with clinical data. In same cases escitalopram prescription was modified after analysis of serum concentrations.