SEATTLE, Jan. 29, 2014 /PRNewswire/ -- Omeros Corporation (NASDAQ: OMER) today announced positive results from a Phase 2a clinical trial of OMS824, the company's phosphodiesterase 10 (PDE10) inhibitor, in which the drug was well tolerated and demonstrated comparable systemic pharmacokinetics when administered alone and concomitantly with approved antipsychotic agents in patients with schizophrenia. OMS824 selectively inhibits PDE10, an enzyme expressed in areas of the brain linked to a wide range of diseases that affect cognition, including schizophrenia and Huntington's disease. In this Phase 2a randomized, double-blind, placebo-controlled trial, OMS824 was administered at two dose levels for two weeks to psychiatrically stable patients whose antipsychotic medications were temporarily discontinued or who continued their usual antipsychotic regimen. The trial enrolled 33 patients, and the results showed that OMS824 was well tolerated, with mild or moderate adverse events that were self-limited and resolved during the treatment period. The tolerability and pharmacokinetics of OMS824 were not affected by concomitant antipsychotic medications, allowing the drug to be developed as both a monotherapy and as adjunctive therapy in combination with currently approved antipsychotics. The plasma concentrations of OMS824 in the high-dose cohort were similar to levels that corresponded to greater than 60 percent target occupancy of PDE10 in a Phase 1 positron emission tomography (PET) trial. Given the small sample size, efficacy conclusions cannot be drawn but the data support continued development in schizophrenia and other neuropsychiatric conditions. The positive results from this Phase 2a trial suggest that dose adjustment will not be necessary when OMS824 is administered in combination with standard antipsychotic medications. Future Phase 2 and Phase 3 clinical trials in Omeros' schizophrenia program may evaluate OMS824 both as a single agent and as adjunctive treatment for cognitive impairment, acute exacerbation of symptoms, and/or inadequate response to antipsychotic medications.