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.
