Comparison of risperidone and mosapramine addition to neuroleptic treatment in chronic schizophrenia

There is little information regarding the effects of risperidone addition t o neuroleptic treatment in chronic schizophrenia. As a preliminary study, 1 0 neuroleptic-treated schizophrenic inpatients received risperidone (high 5 HT(2A)/D-2 ratio, i.e. the ratio between 5HT(2A) and D-2 receptor occupancy ) and mosapramine (low 5HT(2A)/D-2 ratio) in a randomized, single-blind, cr ossover, add-on study consisting of 8 weeks of treatment each with risperid one and mosapramine. Although both additions resulted in significant, albei t modest, improvement, there was no significant difference in the scores on the Positive and Negative Syndrome Scale for Schizophrenia between risperi done and mosapramine addition. These results suggest that risperidone and m osapramine bring about comparable effects in add-on design. Thus, risperido ne with a high 5HT(2A)/D-2 ratio does not seem to be better than mosapramin e with a low 5HT(2A)/D-2 ratio when combined with conventional neuroleptics . Further studies including a large number of patients and a double-blind d esign are needed.