A Study of Paliperidone Palmitate 6-Month Formulation

The purpose of this study is to demonstrate that injection cycles consisting of a single administration of paliperidone palmitate 6-month (PP6M) are not less effective than 2 sequentially administered injections of paliperidone palmitate 3-month PP3M) (350 or 525 mg eq.) for the prevention of relapse in participants with schizophrenia previously stabilized on corresponding doses of paliperidone palmitate 1-month (PP1M) (100 or 150 mg eq.) or PP3M (350 or 525 mg eq.).

The primary hypothesis of this study is that the efficacy of PP6M is non-inferior to PP3M for preventing relapse in participants with schizophrenia who were previously stabilized on corresponding doses of PP1M or PP3M. The study consists of mainly 3 phases: a screening phase (up to 28 days), a maintenance phase (of 1 or 3 months), and a double-blind phase (of 12 months \[neither the researchers nor the participants know what treatment the participant is receiving\]). Additional/conditional phases include a transition phase (before maintenance phase). Study evaluations include efficacy, pharmacokinetics, pharmacodynamics, and safety. The study duration will vary from approximately 13 months to 19 months.

Eligibility Criteria:
Inclusion Criteria:

* Must meet the diagnostic criteria for schizophrenia according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM 5) for at least 6 months before screening
* Must be receiving treatment with paliperidone palmitate (as either the paliperidone palmitate 1-month (PP1M) or paliperidone palmitate 3-month (PP3M) formulation), or injectable risperidone, or any oral antipsychotic
* Must be able, in the opinion of the investigator, to discontinue any antipsychotic medication other than PP1M) or PP3M during the Screening Phase
* Must have a full Positive and Negative Syndrome Scale (PANSS) score of less than (\<) 70 points at screening
* Must have a body mass index (BMI) between 17 and 40 kilogram (kg)/meter (m)\^2 (inclusive) and must have a body weight of at least 47 kg at screening
* Must be willing to receive gluteal injections of medication during the Double-blind Phase

Exclusion Criteria

* Must not be receiving any form of involuntary treatment, such as involuntary psychiatric hospitalization, parole-mandated treatment, or court-mandated treatment
* Must not have attempted suicide within 12 months before screening and must not be at imminent risk of suicide or violent behavior, as clinically assessed by the investigator at the time of screening
* Must not have a DSM-5 diagnosis of moderate or severe substance use disorder (except for nicotine and caffeine) within 6 months of screening; however, acute or intermittent substance use prior to screening is not exclusionary, depending upon the clinical judgment of the investigator
* Must not have a history of neuroleptic malignant syndrome or tardive dyskinesia
* Must not have a history of intolerability or severe reactions to moderate or higher doses of antipsychotic medications and must not have any other factors that would, in the judgment of the investigator, indicate that treatment with moderate or higher doses of paliperidone palmitate would be intolerable or unsafe