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

The purpose of this study is to demonstrate that a paliperidone palmitate 3 month formulation (PP3M) is as effective as the paliperidone palmitate 1 month formulation (PP1M) in the treatment of patients with schizophrenia who have been stabilized on PP1M.

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.

Eligibility Criteria:
Inclusion Criteria:

* Patients with schizophrenia for more than 1 year and whose symptoms are worsening in the opinion of the investigator
* A total score in the Positive and Negative Syndrome Scale (PANSS) between 70 and 120
* Signed informed consent
* Women must not be pregnant, breastfeeding, and if capable of pregnancy must practice an effective method of birth control
* Men must agree to use a double-barrier method of birth control
* Be medically stable on the basis of clinical laboratory tests, physical examination, medical history, vital signs, and electrocardiogram (ECG)

Exclusion Criteria:

* A diagnosis other than schizophrenia, e.g., dissociative disorder, bipolar disorder, major depressive disorder, schizoaffective disorder, schizophreniform disorder, autistic disorder, primary substance-induced psychotic disorder, dementia-related psychosis
* Relevant history or current presence of any significant or unstable medical condition(s) determined to be clinically significant by the Investigator (ie, obesity, diabetes, heart disease etc)
* A diagnosis of substance dependence within 6 months before screening
* History of neuroleptic malignant syndrome (NMS) or tardive dyskinesia
* Clozapine use in the last 2 months when used for treatment-resistant or treatment-refractory illness
* Clinically significant findings in biochemistry, hematology, ECG or urinalysis results
* Any other disease or condition that, in the opinion of the investigator, would make participation not in the best interest of the patient or that could prevent, limit, or confound the protocol-specified assessments