The Effectiveness of Olanzapine, Risperidone, Quetiapine, and Ziprasidone as Augmentation Agents in Treatment-Resistant Major Depressive Disorder

Background: Many questions remain regarding the use of atypical neuroleptics as antidepressant augmentation agents. To date, there have been no reports in the literature regarding the effectiveness of these drugs when trials of one or more of them have failed previously as antidepressant augmentation.

Method: This retrospective chart review was conducted to determine the effectiveness of olanzapine, risperidone, quetiapine, and ziprasidone when given in a fee-for-service setting as antidepressant augmentation agents to patients with treatment-resistant, nonpsychotic major depressive disorder (DSM-IV). Prospective (Global Assessment of Functioning [GAF]) along with retrospective (Clinical Global Impressions-Improvement [CGI-I] and -Severity of Illness scales) ratings were completed for each patient. Analyses were conducted in an attempt to identify factors that appeared to correlate with response, including order of administration and Thase-Rush staging of treatment resistance.

Results: In this study of 76 medication trials in 49 patients, the overall response rate based on the CGI-I ratings was 65% (32/49). Individual rates of response were 57% (21/37) for olanzapine, 50% (7/14) for risperidone, 33% (6/18) for quetiapine, and 10% (1/10) for ziprasidone. None of the differences between neuroleptics in rates of response were significant. The difference between baseline and final GAF scores was statistically significant only in the olanzapine (p < .001) and risperidone (p = .047) groups. Rates of discontinuation did not vary significantly between agents, though trends were present. Crossover trials from one atypical neuroleptic to another in the event of nonresponse appeared to be effective.

Conclusions: Although limited by its design, this study suggests atypical neuroleptic augmentation of antidepressants may be a viable option in treatment-resistant major depressive disorder.