Relationship between clinical effects, serum drug concentration, and concurrent drug interactions in depressed patients treated with citalopram, fluoxetine, clomipramine, paroxetine or venlafaxine

The relationship between clinical effects and plasma concentrations of cita lopram, fluoxetine, clomipramine, paroxetine and venlafaxine was studied in 119 cases of major depression. Clinical effects were evaluated using the C linical Global impression (CGI) improvement scale. Antidepressants were qua ntified by a separative chromatographic methodology. Plasma concentrations in responder patients were compared with the plasma concentrations proposed in literature as effective values. We found that the usual therapeutic win dow is convenient for citalopram and clomipramine, but could be reduced for fluoxetine and increased for venlafaxine and paroxetine. Concurrent drug i nteractions were also evaluated and clomipramine or citalopram plasma level s were found to be influenced by the presence of associated drugs. A larger study is needed, taking into account not only plasma concentrations and cl inical effects, but also some pharmacokinetic data, especially the metaboli c activity characterising the patient, and the presence or not of associate d drugs. Copyright (C) 2000 John Wiley & Sons, Ltd.