Study of Paliperidone Palmitate 3 Month and 1 Month Formulations for the Treatment of Patients With Schizophrenia

This is a randomized (the study drug is assigned by chance), double blind (neither physician nor patient knows the treatment that the patient receives), parallel group (each group of patients will be treated at the same time), multicenter non-inferiority (the effect of the new treatment is not worse than that of the comparison treatment) study. A new formulation of paliperidone palmitate with a 3-month injection interval (PP3M) is being tested for use as maintenance treatment for subjects with schizophrenia who have been first stabilized on paliperidone palmitate with a 1-month injection interval (PP1M). The study consists of 3 phases: a screening/washout/tolerability phase (up to 21 days); a 17-week open-label (all people know the identity of the intervention) stabilization phase (referred to as the Open-label Phase) and a 48-week fixed dose, randomized, double-blind controlled phase (referred to as the Double-blind Phase). After completion of the Screening Phase, all patients will receive PP1M in the Open-label Phase. During this time, flexible dosing will occur at Weeks 5 and 9. At Week 13 patients are to receive the dose of PP1M that was administered at Week 9. Patients who are clinically stable at the end of the Open-label Phase will enter the Double-blind Phase and will be randomly assigned in a 1:1 ratio to receive fixed doses of PP3M or PP1M.