This is a prospective, 4-week, randomized, double-blind, placebo-controlled, study designed to evaluate the safety, tolerability, and preliminary efficacy of an oral dose range of NW-3509A of 30 to 50 mg/day (15 to 25 mg, BID) in patients with chronic schizophrenia on a stable dose of an antipsychotic (aripiprazole or risperidone). A minimum of 90 patients will be randomized in a 1:1 ratio to receive either NW-3509A (n=45) or placebo (n=45). Dose increases will be performed only during in-patient setting.~Safety and efficacy assessments will be done on a weekly basis during the randomized treatment period. The assessment of safety will be based on laboratory tests (biochemistry, hematology, and urinalysis), 12-lead standard ECG, vital signs, physical examinations, neurological examinations, C-SSRS, ESRS-A, subjective reporting of any AE by the subject, objective observation of any AE by the Investigator. Pharmacokinetic samples will be taken at various time-points. Efficacy assessments will include the PANSS, CGI-C, CGI-S and the Strauss-Carpenter Level of Functioning (LOF) scale.
A 4-week Phase IIa study to evaluate the safety and tolerability and efficacy of NW-3509A in patients with chronic schizophrenia that are not responding adequately to their current antipsychotic medication (aripiprazole or risperidone). NW-3509A is given as an oral dose range of 15 to 25 mg, BID in a 1:1 ratio.