Antidepressant response and fluvoxamine plasma concentrations: a pilot study.

The objective of this pilot study was to examine the relation between fluvoxamine (FVX) plasma concentrations, therapeutic response and side effects during a four-week treatment period. Twenty-two patients who met the DSM-IV criteria for major depression received 100 mg FVX during the first 2 days of treatment and then 150 or 200 mg/day. No clear relationship between plasma concentrations and side effects was detectable. A relationship between plasma concentrations and clinical efficacy was detectable after 21 days but not after 28 days of treatment. These preliminary results indicate that therapeutic drug monitoring might be useful for patients treated with FVX.