You can contact 866-971-0917 to speak to one of the study staff about the study, eligibility to participate, site referrals, etc.

In refractory schizophrenia, the symptoms cannot be improved much by the antipsychotic medications and patients with refractory schizophrenia are taking the last line medication of clozapine. about 10-20% of people suffering from schizophrenia are taking clozapine worldwide. furthermore, only about one third of clozapine-treated patients can improve with the treatment.

Status: Recruiting

The SND12 study is looking at whether a potential new medication called NaBen® is safe and effective in improving symptoms of schizophrenia in clozapine-treated refractory patients. The goal of this study is to increase treatment options available for refractory schizophrenia.
Low function of the N-methyl-D-Aspartate receptor (NMDAR) subtype glutamate receptor in the brain plays an important role in the pathophysiology of schizophrenia. Enhancing NMDAR-mediated brain signaling is considered a novel treatment approach in improving schizophrenia associated symptoms. One method to enhance NMDA function is to raise the levels of D-amino acid (DAA) by reducing their metabolism via DAA oxidase (DAAO) inhibitors. NaBen® is a readily available DAAO inhibitor with a well- developed safety profile, and has received the FDA orphan product designations for the indications of schizophrenia in the pediatric population and patients with refractory schizophrenia receiving clozapine therapy. NaBen® is also designated as a breakthrough therapy in adult schizophrenia. Previous studies have shown excellent efficacy and safety for NaBen® in improving schizophrenia symptoms. This multi-center, randomized, placebo- controlled, parallel-group study is to further assess the safety and efficacy of NaBen® in improving symptoms of refractory schizophrenia.
Male and Female subjects joining the study will need to visit the study center several times during a period of up to 12 weeks. There will be a total 7 visits during the 12 weeks including screening, double-blind treatment and follow-up phases. The study is divided in to three phases:
  • Screening phase (2 weeks)
  • Treatment phase (8 weeks)
  • Follow-up phase (2 weeks)
At each visit, the study doctor will ask questions about the schizophrenia symptoms. Overall health will be monitored throughout the study using:
  • Physical examinations
  • Blood pressure and heart rate, EKG test
  • Blood and urine test
The cost of all study-related health assessments and study medication in the study will be covered. During this study you will not be taken off your current medication. NaBen® will be added to your current treatment as an additional.
Major Inclusion criteria:
  • Male or female subjects who are between 18 and 55 years of age
  • Confirmed diagnosis of schizophrenia and have refractory schizophrenia as defined below (should meet at least two: either a and b; or a and c; or a and b and c):
    • Prior non-response to at least 2 antipsychotic drugs of two different chemical classes for at least 4-6 weeks each at doses ≥ 400 mg equivalents of chlorpromazine or 4 mg/day risperidone, AND
    • No period of good functioning in previous 2 years; OR,
    • Moderate to severe psychopathology (total PANSS score equal or more than 70): including persistent psychotic symptoms, recurrent mood symptoms, repeated suicide attempts or suicidal ideation, uncontrolled aggressive behavior, moderate to severe positive or negative symptoms or moderate-severe cognitive impairment
  • The subject has a minimum PANSS total score of 70 at the Screening and Baseline Visits
  • Body Mass Index (BMI) between 17 and 38
  • The subject has been receiving clozapine for a minimum of 6 months with the dose range of 200-900 mg/day. The dose should have remained unchanged for at least 3 months prior to Screening and not expected to change during the study

Major Exclusion criteria:
  • At Screening meets the DSM criteria for major mental illness other than schizophrenia
  • Initiation or dose change of lithium, antidepressant or other mood stabilizers within 16 weeks prior to Screening
  • Initiation or dose change of benzodiazepines or sleep medications, or any other psychotropic medications due to worsening of schizophrenia symptoms or medication side effects within four (4) weeks prior to Screening
  • The subject has previously received NaBen®
  • Current substance abuse or positive urine illicit drug screening or history of substance dependence

For more detailed information about the SND12 study, please see the US FDA clinical trial website below: (detailed description of SND12)

If you would like to know more about the SND12 Study, please speak with your family doctor or psychiatrist, who may refer you to the local study team using the contact information below. They will be happy to give you more information about the study and answer any of your questions.