<br>        Inclusion criteria:<br><br>        For inclusion in the study patients must fulfil all of the following criteria:<br><br>          1. Inpatients (the admission to hospital occurs independently from study participation)<br><br>          2. Provision of written informed consent<br><br>          3. A diagnosis of major depression by Diagnostic and Statistical Manual of Mental<br>             Disorders- Fourth Edition (DSM-IV) (unipolar depression: 296.2, 296.3)<br><br>          4. Female and male patients aged 18 to 65 years<br><br>          5. Female patients of childbearing potential must have a negative serum human chorionic<br>             gonadotropin (hCG) pregnancy test at enrolment and e willing to use a reliable method<br>             of birth control (i.e. barrier method, oral contraceptive, implant, dermal<br>             contraception, long-term injectable contraceptive, intrauterine device, or tubal<br>             litigation) during the study.<br><br>          6. Able to understand and comply with the requirements of the study as judged by the<br>             investigator.<br><br>          7. A sum score of at least 18 on the 21-item version of the Hamilton Depression Rating<br>             Scale (21-HAMD)<br><br>        Exclusion criteria:<br><br>        Any of the following is regarded as a criterion for exclusion from the study:<br><br>          1. Pregnancy or lactation<br><br>          2. Any DSM-IV Axis I disorder not defined in the inclusion criteria<br><br>          3. Patients who, in the opinion of the investigator, pose an imminent risk of suicide or<br>             a danger to self or others<br><br>          4. Known intolerance or lack of response to quetiapine fumarate and/or escitalopram, as<br>             judged by the investigator<br><br>          5. Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding<br>             enrolment including but not limited to: ketoconazole, itraconazole, fluconazole,<br>             erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir,<br>             fluvoxamine and saquinavir<br><br>          6. Use of any of the following cytochrome P450 3A4 inducers in the 14 days preceding<br>             enrolment including but not limited to: phenytoin, carbamazepine, barbiturates,<br>             rifampin, St. John's Wort, and glucocorticoids<br><br>          7. Use of monoamine oxidase inhibitors (MAOIs) or other serotonergic drugs (e.g.<br>             triptans) in the 14 days preceding enrolment<br><br>          8. Use of oral anticoagulants in the 14 days preceding enrolment<br><br>          9. History of bleeding disorders.<br><br>         10. Use of drugs which are mainly metabolized by cytochrome P450 2D6 having a low<br>             therapeutic index (e.g. flecainide, propafenone, metoprolol) in the 14 days preceding<br>             enrolment<br><br>         11. Administration of a depot antipsychotic injection within one dosing interval (for the<br>             depot) before randomisation<br><br>         12. Substance or alcohol dependence at enrolment (except dependence in full remission,<br>             and except for caffeine or nicotine dependence), as defined by DSM-IV criteria<br><br>         13. Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV<br>             criteria within 4 weeks prior to enrolment<br><br>         14. Medical conditions that would affect absorption, distribution, metabolism, or<br>             excretion of study treatment<br><br>         15. Unstable or inadequately treated medical illness (e.g. congestive heart failure,<br>             angina pectoris, hypertension) as judged by the investigator<br><br>         16. Involvement in the planning and conduct of the study<br><br>         17. Previous enrolment or randomisation of treatment in the present study.<br><br>         18. Participation in another drug trial within 4 weeks prior enrolment into this study or<br>             longer in accordance with local requirements<br><br>         19. A patient with Diabetes Mellitus (DM) fulfilling one of the following criteria:<br><br>               -  Unstable DM defined as enrolment glycosylated hemoglobin (HbA1c) >8.5%.<br><br>               -  Admitted to hospital for treatment of DM or DM related illness in past 12 weeks.<br><br>               -  Not under physician care for DM<br><br>               -  Physician responsible for patient's DM care has not indicated that patient's DM<br>                  is controlled.<br><br>               -  Physician responsible for patient's DM care has not approved patient's<br>                  participation in the study<br><br>               -  Has not been on the same dose of oral hypoglycaemic drug(s) and/or diet for the<br>                  4 weeks prior to randomisation. For thiazolidinediones (glitazones) this period<br>                  should not be less than 8 Weeks.<br><br>               -  Taking insulin whose daily dose on one occasion in the past 4 weeks has been<br>                  more than 10% above or below their mean dose in the preceding 4 weeks Note: If a<br>                  diabetic patient meets one of these criteria, the patient is to be excluded even<br>                  if the treating physician believes that the patient is stable and can<br>                  participate in the study.<br><br>         20. An absolute neutrophil count (ANC) of 1.5 x 109 per liter<br><br>         21. Abnormal laboratory parameters of clinical relevance before enrolment<br><br>         22. Abnormal blood pressure, abnormal electrocardiogram, and/or abnormal<br>             electroencephalogram with clinical relevance before enrolment<br><br>         23. Psychotropic drugs within 3 days before and throughout the study with the exception<br>             of zopiclon (up to 7.5 mg per day) in case of sleep difficulties and lorazepam (up to<br>             2 mg per day) in case of inner tension and anxiety<br>