Efficacy, Safety and Pharmacokinetics Study of CPL500036 (PDE10A Inhibitor) in Patients With Schizophrenia

This is a double-blind, randomized, placebo controlled, parallel group, dose ranging study to explore the efficacy, safety, tolerability and PK of 2 different doses of CPL500036 (phosphodiesterase 10A \[PDE10A\] inhibitor) in patients with an acute exacerbation of schizophrenia. Approximately 165 patients will be randomized at a 1:1:1 ratio and will be dosed with 20 mg CPL500036, 40 mg CPL500036 or placebo once daily for 28 consecutive days (Day 1 to Day 28). Patients will remain in house for the duration of the Treatment Period. The study will comprise of a Screening Period (that will include a prior Medication Washout Period), a Treatment Period and a Follow-up Period. After discharge from the Clinical Unit, patients will return to the Clinical Unit for 2 once weekly Follow-up Visits. Approximately 30% of the patients (17 patients in each of the 3 treatment groups) will undergo extensive PK sampling during the Treatment Period, and the remaining 70% of the patients will only undergo sparse PK sampling.