A Study to Evaluate the Effect of Oral Paliperidone Extended-Release and Oral Risperidone Immediate-Release on Cognitive Function in Clinically Stable Patients With Schizophrenia

A Randomized, Open-Label, Study To Evaluate The Effect of Oral Paliperidone Extended-Release and Oral Risperidone Immediate-Release on Selected Cognitive Domains in Clinically Stable Subjects With Schizophrenia

The purpose of this study is to compare the effect of oral paliperidone extended-release and oral risperidone immediate-release on cognitive function, especially the category fluency of Cognitive Abilities Screening Instrument, Chinese version (CASI C-2.0), in patients with an established diagnosis of schizophrenia.

This is a 28-week, randomized (the study medication is assigned by chance), open-label (all people know the identity of the intervention), active-controlled (patients are assigned to either a recognized effective treatment or the study medication) comparative study. All patients will enter a run-in period to receive a stable therapeutic dose of oral risperidone immediate-release for at least 4 weeks. After the 4-week run-in period, patients will be randomly assigned to either remain on oral risperidone immediate-release (IR) or to receive a therapeutic dose of oral paliperidone extended-release (ER) and patients will be prospectively followed for a 24-week treatment phase. The treatment phase is composed of a 4-week flexible dose period followed by a 20-week stable dose period. During the 4-week flexible dose period, the dose of paliperidone ER or risperidone IR may be increased or decreased for each patient if clinically indicated (eg, significant side effects emerge or there is evidence of a lack of efficacy). At the end of 4-week flexible dose period, the final dose should be maintained for the 20-week fixed-dose period. Efficacy and safety will be assessed at baseline (Week 0) and Weeks 4, 12, and 24.

Inclusion Criteria:

• Diagnosed with schizophrenia
• Cognitive abilities screening instrument C-2.0 total score between 50 and 85 (inclusive) at baseline
• Baseline positive and negative syndrome scale score between 60 and 85 (inclusive)
• Clinical global impression-severity change less than or equal to 1 in the month prior to randomization
• Patients on a stable therapeutic dose of oral risperidone IR (between 3-6 mg/day) for at least 4 weeks prior to randomization

Exclusion Criteria:

• Treatment refractory patients, defined as failure of more than or equal to 2 adequate trials of second generation antipsychotic treatment for schizophrenia
• History of neuroleptic malignant syndrome
• Allergy or hypersensitivity to risperidone or paliperidone, or to any of the excipients of oral risperidone IR or paliperidone ER tablets
• Participants who have taken paliperidone ER in the past
• Participants who have been treated with clozapine or any long-acting injectable (depot) antipsychotic within 3 months before randomization