Risperidone as an adjunct to clozapine therapy in chronic schizophrenics.

Background: Some treatment-resistant schizophrenic patients improve enough to remain out of the hospital but continue to have significant positive or negative symptoms.
Method: The goal of this study was to assess the safety and potential efficacy of risperidone as an adjunct for schizophrenic patients treated with clozapine. In an open 4-week trial involving 12 DSM-III-R-diagnosed patients, the addition of risperidone to clozapine was well tolerated and did not affect serum clozapine concentrations significantly.
Results: Total Brief Psychiatric Rating Scale (BPRS) scores and subscales measuring positive symptoms, negative symptoms, and depressive symptoms were significantly reduced from baseline. Ten of 12 participants had a 20% or greater reduction in the total BPRS score.
Conclusion: In this open trial, the addition of risperidone to clozapine was well tolerated and produced significant reduction of symptoms, suggesting that this may be a useful clinical approach. Because this was an open trial, the improvement we observed must be replicated in a controlled trial.