A Six-week, Randomized, Double-blind, Placebo-controlled, Parallel Group, Multi-center, Phase II Study

This study consists of a 5- to 14-day screening period to include antipsychotic medication washout, followed by a six-week double blind treatment period. Patients completing the 6-week treatment period may continue double-blind treatment in an optional extension period of at least 6 weeks' duration. Patients randomized to placebo during the initial 6-week period will be randomized to BL-1020 low or high dose during the extension treatment period. Approximately 40 study centers in four countries will participate.