This 4-week study will evaluate the safety, tolerability and preliminary evidence of efficacy of evenamide (7.5,and 15 mg and placebo, bid) treatment in outpatients with chronic schizophrenia.

This is a prospective, 4-week, randomized, double-blind, placebo-controlled, study designed to evaluate the safety, tolerability, EEG effects, and preliminary efficacy of two fixed oral doses of evenamide of 7.5 mg and 15 mg bid (15 and 30 mg/day) in outpatients with chronic schizophrenia who are receiving treatment at constant doses of one of the following atypical antipsychotics: aripiprazole, clozapine, quetiapine, olanzapine, paliperidone or risperidone. Approximately 120 patients will be randomized in a 1:1:1 ratio to receive either evenamide 7.5 or 15 mg, or placebo, given bid.

Inclusion Criteria:

Demographics

• Age - 18 years, or older
• Sex - male, or non-childbearing potential female unless practicing adequate contraception

Psychiatric

• Has a current diagnosis of schizophrenia in accordance with DSM-5.
• Has been treated with antipsychotics for at least 2 years.
• Has a total score on the PANSS < 80.
• Has a Clinical Global Impression - Severity of disease (CGI-S) rating of mildly, moderately or moderately severely ill (score of 3, 4 or 5).
• Needs antipsychotic treatment and is currently receiving a stable dose (minimally for 4 weeks prior to screening) of aripiprazole, clozapine, quetiapine, olanzapine, paliperidone, or risperidone (at least 2 mg risperidone dose-equivalent)
• Current symptoms have been stably present for at least one month

Procedural

• Patient resides at home or in a residential care facility
• If taking clozapine, patient agrees to blood monitoring

Exclusion Criteria:

Psychiatric

• Severity of current episode of psychosis requires that the patient be hospitalized. Patients who are chronically hospitalized or in psychiatric day-care, whose hospitalization is for logistic reasons and not due to the severity of their illness, will be eligible for the study.
• Severity of psychosis is rated severe or higher (CGI-S of 6 or greater).
• Known suicidal risk. A "yes" response on the C-SSRS Suicidal Ideation Item 4 or Item 5, or a "yes" response on any of the five C-SSRS Suicidal Behavior items, at screening, or a suicide attempt within the past 6 months, excludes the patient from the study.
• Patients with a diagnosis of Treatment resistance
• History of neuroleptic malignant syndrome, priapism.
• Current moderate or severe tardive dyskinesia.

Medical Status

• Abnormal epileptiform phenomena (3 per second spike and slow wave discharges) observed on screening EEG. History or current diagnosis of epilepsy or seizure disorder (other than febrile seizures in childhood)
• Insulin-dependent diabetes mellitus
• History or current diagnosis of any neurodegenerative illnesses
• Loss of 500 ml or more of blood during the 3-month period before study enrollment, e.g. as a donor

Cardiovascular

• A current diagnosis of severe or unstable cardiovascular disease
• Any clinically significant ECG abnormality
• Abnormal vital signs

Laboratory abnormalities

• Clinically significant abnormalities in routine laboratory examinations
• History and/or presence of hepatitis B and/or C
• Positive results from the HIV serology.
• Positive results of the drug and alcohol tests
• Clinically significant or unstable hypothyroidism or hyperthyroidism

Concomitant therapy

• Treatment with SSRIs that are moderate/potent inhibitors of CYP2D6 (e.g. fluoxetine)
• Treatment with drugs capable of inducing/inhibiting hepatic enzyme metabolism
• Current treatment with sodium channel blockers
• Exposure to any investigational drug within 5 weeks or 5 half-lives (whichever is longer) prior to screening
• A known exaggerated pharmacological sensitivity or hypersensitivity to drugs similar to evenamide (e.g. lamotrigine, carbamazepine, oxcarbazepine, topiramate, etc.), or any components of the evenamide or matching placebo capsules
• Treatment with a drug or treatment known to cause major organ system toxicity, e.g. tamoxifen, within 4 weeks, or received radiation therapy or a drug with cytotoxic potential, e.g. chemotherapy, during the past year
• Electroconvulsive therapy (ECT) or treatment with a transcranial magnetic stimulation (TMS) device within 6 months prior to screening