Study to Evaluate the Efficacy and Safety of Risperidone in Situ Microparticle (ISM)® in Patients With Acute Schizophrenia

The study design includes a screening period, a 12-week treatment period, and a follow-up period. Eligible patients will be randomly assigned, under double-blind conditions, to receive the following study drug treatments in a 1:1:1 ratio during the double-blind treatment period: Risperidone ISM® 75 mg, Risperidone ISM® 100 mg, or placebo. The IM study drug (double-blind active Risperidone ISM® or placebo) will be administered in a deltoid or gluteal muscle for a total of 3 times, once every 4 weeks, during the 12-week treatment period. If indicated for an individual patient, prohibited medications may be washed out during the screening period. Patients who have never taken Risperidone must have a brief trial of oral Risperidone in order to ensure a lack of any clinically significant hypersensitivity reactions before the first dose of the study drug is administered. Efficacy will be assessed by describing changes in scores on standard psychiatric assessment tools at each visit. Safety assessments will also be conducted at each visit. The primary objective of this study is the following: • To evaluate the efficacy of Risperidone ISM as compared with that of placebo in the treatment of patients with acute exacerbation of schizophrenia The secondary objectives of this study are the following: * To characterize safety and tolerability of Risperidone ISM as compared with that of placebo in patients with acute exacerbation of schizophrenia * To quantify healthcare resource utilization (HRU), health-related quality of life (HRQL), and social functioning in patients treated with Risperidone ISM versus placebo for an acute exacerbation of schizophrenia * To explore pharmacokinetic characteristics of Risperidone ISM and associations with efficacy Patients who complete planned double-blind study drug treatments and study evaluations may be eligible to participate in an optional long-term extension segment of the study in which treatment with open-label Risperidone ISM 75 or 100 mg (randomly assigned) would begin immediately; for patients who do not participate in the extension segment, a safety follow-up phone contact will occur after the end-of-treatment visit. In addition to patients continuing from the double-blind segment of the study (rollover patients), patients not previously enrolled in the study (de novo patients) may be eligible to enter the long-term extension segment of the study. These patients will be evaluated for eligibility at a screening visit and, if eligible, will be allocated to receive either 75 or 100 mg Risperidone ISM every 4 weeks for approximately 12 months.