To assess the effect of zicronapine versus risperidone on metabolic parameters comprising body weight, body mass index (BMI), waist circumference, levels of fasting blood lipids and glucose during 6 months of treatment.

Schizophrenia is a serious and disabling mental disorder that affects approximately 1% of the world's population. Antipsychotic drugs remain the cornerstone in the pharmacotherapy of schizophrenia. There are a number of antipsychotic drugs in use but none is ideal, in particular because their safety profile is complex and their effectiveness is limited.

Thus, present treatment options leave room for improvement and call for new, more effective pharmacotherapies for the treatment of schizophrenia. In the current study, non-acute patients with schizophrenia will be randomised to blinded treatment with either zicronapine or a standard antipsychotic treatment for 24 weeks. The safety (with focus on metabolic parameters) and efficacy of zicronapine will be evaluated in comparison to risperidone.

Inclusion Criteria:

• The patient meets the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR) criteria for schizophrenia
• The patient is a man or woman, ≥18 and ≤65 years old
• The patient has a PANSS total score ≥60 and ≤100 (extremes included) at screening and baseline

Exclusion Criteria:

• The patient has a current, predominant Axis I psychiatric disorder other than schizophrenia as defined in the DSM-IV-TR
• The patient has a current diagnosis or a history of substance dependence (except nicotine) or substance abuse (except cannabis) according to the DSM-IV-TR criteria ≤6 months prior to screening
• The patient is at significant risk of harming him/herself or others according to the investigator's judgement (assisted by the assessment of suicidal ideation and behaviour using the C-SSRS)
• The patient is resistant to antipsychotic treatment according to the investigator's judgement or has been treated with clozapine ≤3 months prior to screening
• The patient has experienced an acute exacerbation requiring hospitalisation ≤3 months prior to screening or between screening and baseline
• The patient has been treated with risperidone or paliperidone ≤6 months prior to screening

Other inclusion and exclusion criteria may apply.