A Randomized, Double-blind, Placebo-controlled, Parallel-group, Dose-response Study to Evaluate the Efficacy and Safety of 3 Fixed Doses (25 mg eq, 50 mg eq, and 100 mg eq) of Paliperidone Palmitate in Patients With Schizophrenia

Many patients with schizophrenia have difficulty adhering to a daily oral treatment regimen. Long-acting injectable (LAI) formulations may provide therapeutic plasma concentrations over several weeks, thereby eliminating the need for daily oral medication and making compliance easier. This is a randomized (patients will be assigned to different treatment groups based solely on chance), double-blind (neither the patient nor the physician will know if placebo or drug is being given and at what dose), placebo-controlled, parallel group, multicenter, dose-response study in adults who have schizophrenia. The study consists of a screening period of no more than 7 days and a 13-week double-blind treatment period. The screening period includes 4 days for tolerability testing, if necessary. In the double-blind treatment period, patients will be randomly assigned to 1 of 4 treatment groups (3 fixed doses of paliperidone palmitate or placebo) to receive 4 i.m. injections of paliperidone palmitate or placebo on Days 1, 8, 36, and 64. The study, including the screening period, will last approximately 14 weeks. Efficacy will be assessed throughout the study using the Positive and Negative Symptom Scale for Schizophrenia (PANSS), the Clinical Global Impression-Severity (CGI-S), and the Personal and Social Performance Scale (PSP). Safety will be evaluated throughout the study by monitoring adverse events, extrapyramidal symptom (EPS) rating scales scores, clinical laboratory test results; vital signs and body weight measurements; electrocardiograms (ECGs); and physical examination findings. In addition, the tolerability of injections will be assessed. ER OROS paliperidone 3 mg/day for 4 days. Injections (i.m.) of paliperidone palmitate (25, 50, or 100 mg eq.) will be given on Days 1, 8, 36, and 64.