The main purpose with the study is to evaluate the efficacy and safety of Lu 31-130 in patients suffering from schizophrenia compared to placebo.

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. However, none of the available drugs is ideal, in particular because of their complex safety profile and the limited effectiveness against certain symptoms of the disease. Thus, only one dimension of the morbidity, that is, the positive symptoms, can be expected to respond to treatment whereas negative symptoms and cognitive deficits are, at best, only marginally targeted.

Given this, there is no doubt that the current antipsychotic drugs leave much room for improvement and call for new, more effective pharmacotherapies in the treatment of schizophrenia. In the current study, patients suffering from schizophrenia and experiencing clinically significant symptoms of the disease will be included. In the current study, eligible patients will be randomised in a 2:1 ratio to blinded treatment with either Lu 31-130 (3, 5, 7, 10 or 14 mg/day) or placebo for 8 weeks. The study includes 5 parts with increasing doses of Lu 31-130 (Part A [3 mg/day], B [5 mg/day], C [7 mg/day], D [10 mg/day], and E [14 mg/day]). A decision to initiate Part B [5 mg/day of Lu 31-130], C [7 mg/day of Lu 31-130] or D [10 mg/day of Lu 31-130] will be based on safety and tolerability of the previous study part. Dependent on the safety, tolerability and PK data from Part D the study may proceed with Part E. The efficacy and the safety of Lu 31-130 will be evaluated in comparison to the pooled placebo group from all 5 study parts.

Inclusion Criteria:

• The patient has a primary diagnosis of schizophrenia
• The patient experiences clinically significant symptoms
• The patient did not experience an acute exacerbation requiring hospitalisation within the last 6 months
• The patient's medication has been stable for at least 4 weeks prior screening
• The subject has normal serum values of parameters associated with liver function