Compare the Effect on Cognitive Functioning of Two Formulations of Seroquel, Seroquel XR and IR in Patients With Stable Schizophrenia

A Phase IV Prospective, Double-blind, Double-dummy, Randomised, Crossover Study to Assess the Impact on Daily Cognitive Functioning of Quetiapine Fumarate Immediate Release (Seroquel IR®) Dosed Twice Daily and Quetiapine Fumarate Extended Release (Seroquel XR®) Dosed Once Daily in the Evening in Patients With Stable Schizophrenia

This will be a phase IV 20 -32 day prospective, double blind, double-dummy, randomised crossover study that will evaluate the effect of quetiapine XR and quetiapine IR on cognitive performance in patients with schizophrenia stabilized on a single antipsychotic medication.

Inclusion Criteria:

• Provision of written informed consent prior to any study specific procedures
• Documented clinical diagnosis of schizophrenia, paranoid type, for at least 2 years before randomisation meeting the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV, American Psychiatric Association 2000) criteria of schizophrenia (DSM-IV codes 295.3) confirmed by MINI version 5.0
• Outpatient status at enrolment
• Dose of quetiapine IR or quetiapine XR unchanged during the last 56 days before randomisation

Exclusion Criteria:

• Diagnosis of any DSM-IV Axis I disorder other than those included in inclusion criteria above within 6 months before randomisation (e.g., alcohol dependence or psychoactive substance dependence not in full remission, concurrent organic mental disorder, or mental retardation [axis II diagnosis]) of a degree that may interfere with the patient's ability to co-operate.
• Previous stable use of high dosage of benzodiazepines during one year or more
• Significant neurological medical history (complicated head trauma as judged by the investigator, epilepsy, meningo-encephalitis)
• Use of the following medication:
• other antipsychotic drug than quetiapine within 28 days prior to randomisation
• a depot antipsychotic injection within two dosing intervals (for the depot) before randomisation (Visit 2)
• other psychoactive drugs within 14 days prior to randomisation (hypnotic or anxiolytic drugs, other than those allowed)
• Use of concomitant therapy likely to affect cognition, Medication prohibited 28 days prior to randomisation: benzodiazepines, amphetamines, reboxitin, atomoxinetine, buspiron, donepezil, duloxetine, galantamine, ginko biloba, memantine, methylphenidate, modafinil, rivastigmine, tacrine, smoking cessation therapy varencicline and any dosage form of nicotine replacement therapy. Medication prohibited 14 days prior to randomisation: irreversible monoamine oxidase inhibitors (MAOI), tricyclic antidepressants (TCA), biperiden, antoicholinergic agents (even if the indications are extra pyramidal symptoms or urinary symptoms)