PALIPERIDONE IS MAJOR ACTIVE METABOLITE OF RISPERIDONE. THE MECHANISM OF ACTION OF PALIPERIDONE, AS WITH OTHER DRUGS HAVING EFFICACY IN SCHIZOPHRENIA, IS UNKNOWN, BUT IT HAS BEEN PROPOSED THAT THE DRUG'S THERAPEUTIC ACTIVITY IN SCHIZOPHRENIA IS MEDIATED THROUGH A COMBINATION OF CENTRAL DOPAMINE TYPE 2 (D2) AND SEROTONIN TYPE 2 (5HT2A) RECEPTOR ANTAGONISM.