This study is designed to compare the efficacy and drug tolerability of two strategies for the treatment of schizophrenia. The two strategies consist of utilizing, on the one hand, a conventional antipsychotic like haloperidol or flupentixol and, on the other hand, a newer antipsychotic compound like olanzapine, quetiapine or aripiprazole in patients with schizophrenia.

There is agreement in the psychiatry community that the so-called atypical antipsychotics should be considered first choice in the treatment of schizophrenic disorders. However, the general superiority of these newer antipsychotic drugs over the older conventional drugs could not be clearly demonstrated in recent controlled clinical trials. The discrepancy between every day's clinical perception and the results of clinical trials raises the question whether the studies performed so far employed the adequate methodological approach to represent the daily practice situation which is characterized by a wide variety of duration and type of the schizophrenic disorder, concomitant diseases, and medications. Moreover, some studies might not have been focused adequately on patient-relevant outcome variables.

The present study project is designed to answer these open questions. The innovative character of the study design is

1. that different neuroleptic strategies will be compared rather than single antipsychotic drugs, using
2. an enhanced biometric design, that provides a choice of treatment with respect to the individual patient though the trial as such is randomised controlled and double blind;
3. that clinically relevant endpoints such as quality of life will be the primary variables, and
4. inclusion and exclusion criteria lead to a study population representing clinical every day practice as near as possible.

Another innovatory procedure is that serum levels of the study drugs will be recorded twice during the study. The authors hope that their design might yield transfer effects for other clinical trials facing similar problems.

Inclusion Criteria:

• Schizophrenia
• age 18-65 years
• necessity to establish new or change antipsychotic treatment due to unsatisfying results or side effects
• written informed consent

Exclusion Criteria (amongst others):

• Known or suspected hypersensitivity to olanzapine, quetiapine, aripiprazole, flupentixol or haloperidol
• Acute suicidal tendency
• "Einwilligungsvorbehalt (BGB)" or "Unterbringung (PsychKG)"
• Epilepsy
• Organic psychosis
• Parkinson Disease
• Dementia
• History of malignant neuroleptic syndrome
• QTc interval ≥ 0.5s / history of congenital QTc prolongation