SERUM CONCENTRATIONS OF FLUVOXAMINE AND CLINICAL EFFECTS - A PROSPECTIVE OPEN CLINICAL-TRIAL

This pilot study examined prospectively blood serum concentrations of fluvoxamine, side effects and therapeutic response after a fixed dosag e of 100 mg fluvoxamine/day for 14 days. Twenty male and female patien ts who met the DSM-IV criteria of a major depression received 50 mg fl uvoxamine b.i.d. for two weeks. On days 7 and 14 side effects and ther apeutic response were registered and serum concentrations of fluvoxami ne were determined. A Receiver Operating Characteristic (ROC) curve wa s constructed to determine a possible relationship between serum conce ntrations and clinical effects. The serum concentrations of fluvoxamin e were highly variable, even when dosages were corrected for body weig ht, ranging between 23 to 227 mu g/l. No relationship between serum co ncentrations and side effects was detectable. On the other hand, ROC a nalysis, conducted on day 14, revealed a significant upper concentrati on threshold of 85 mu g/l (p < 0.01) with no responder above this thre shold. The results of this pilot study should be regarded as a hint at the possible therapeutic benefits of lower fluvoxamine serum concentr ations by means of lower fluvoxamine dosages. Furthermore, this indica tes for the first time that therapeutic drug monitoring might be usefu l for patients under antidepressant therapy with fluvoxamine.