Abstract

Augmentation of Olanzapine by Fluphenazine Decanoate in Poorly Responsive Schizophrenia

Author(s): Saeed Shoja Shafti

Introduction: Evidence suggests that atypical antipsychotics affect a broader range of schizophrenic psychopathology and are generally better tolerated than conventional antipsychotics. Therefore, they have become the most commonly used class of antipsychotic drugs in clinical practice. But poor compliance and resistance is noteworthy even among those receiving atypical drugs. The objective of this study was to examine whether there could be any encouraging outcome if fluphenazine decanoate was added, as an adjuvant, to olanzapine in poorly responsive cases of schizophrenia. Method: Twenty-eight female inpatients with a diagnosis of schizophrenia, according to the Structured Clinical Interview for DSM Disorders’ diagnostic criteria, who had shown poor response to olanzapine, were entered into a twelve-week, parallel group, double-blind study for random assignment to either fluphenazine decanoate or placebo in a 1:1 ratio. Primary outcome measures of the study were changes in the mean total scores of the Scale for Assessment of Positive Symptoms (SAPS) and the Scale for Assessment of Negative Symptoms (SANS). The secondary measures were the Schedule for Assessment of Insight (SAI), the Clinical Global Impressions-Severity of Illness (CGI-S) and the Simpson-Angus Scale (SAS). Treatment efficacy was analyzed by t-test, split-plot (mixed) and repeated measures analysis of variance (ANOVA) comparing both groups over twelve weeks. All secondary measures (SAS, SAI, and CGIS) were analyzed by t-test. Results: According to the findings, the mean total scores of SAPS (P<0.01), SAI (P<0.0001) and CGI-S (P<0.03) in the “fluphenazine plus olanzapine” group were decreased significantly in comparison with the “placebo plus olanzapine group.” In spite of an increase in mean total score of SANS in the target group, there was no significant difference in this regard at the study’s conclusion (P<0.09). The mean total score of SAS was also increased significantly in the augmented group (P<0.0001). Effect size (ES) analyses for changes in SAPS, SAI and CGI-S at the end of treatment indicated a large improvement with the fluphenazine augmentation. Conclusions: Adding fluphenazine decanoate to olanzapine may improve some cases of poorly responsive schizophrenia. However, it is essential that consideration be given to the emergence of extrapyramidal side effects and the strengthening of negative symptoms due to fluphenazine, and the probable pharmacokinetic interaction between the two drugs

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