1. As many as 30% of depressed patients fail to respond to
antidepressant drug therapy, and at least 60%-75% will not achieve complete recovery. Recently, several studies have suggested that newer, "second generation"
antidepressants might be beneficial in
treatment resistant depression (TRD). In the present study the authors examined the potential utility of
fluoxetine in TRD by comparing its efficacy in patients with and without a prior history of
antidepressant response. 2. 149 patients with MDD received
fluoxetine 20mg daily for a minimum of 5 weeks: 43 (29%) had never responded to
drug therapy (TRD patients), 41 (28%) did have a prior
drug response (non-TRD patients) and 65 (44%) had never received any
antidepressant treatment. Clinical response was defined as a > or = 50% reduction in baseline Hamilton Depression Rating score plus a final score < 7. 3. Compared to non-TRD patients, the TRD patients were more likely to have
unipolar depression (p = 0.002), a chronic episode of > 2 years duration (p < 0.0001), a later age of illness onset (p < 0.0001), fewer prior episodes (p < 0.0001) and fewer prior
drug treatments (p = 0.04). Overall, the response rate to
fluoxetine was slightly greater in the non-TRD patients (76%) compared to the TRD patients (56%); however, this difference did not achieve statistical significance. 4. The present observations suggest that
fluoxetine treatment of adequate duration may be beneficial for some patients with a prior history of
refractory depression.