The objective of the study was to evaluate the safety and plasma concentration changes of quetiapine after multiple oral administration of FK949E (extended-release formulation of quetiapine) in patients with major depressive disorder (MDD).

This is a dose-titration study. In low-dose-group, patients receive prescribed dose on Day 5 after 3-step dose increases. In high-dose-group patients receive prescribed dose on Day 7 after 4-step dose increases. Patients receive prescribed dose of FK949E for 7 days in each group. The dosage period is 12 days in low dose group and 14 days in high dose group.

Inclusion Criteria:

• Diagnosis of major depressive disorder according to the DSM-IV-TR (Text Revision of the Diagnostic and Statistical Manual of Mental Disorders version-4)
• Female patients of childbearing potential with a negative serum pregnancy test result and who were willing and able to use a reliable method of birth control during the study
• Patients who could understand and comply with the requirements of the study, as judged by the investigator/sub-investigator

Exclusion Criteria:

• A current or past history of a DSM-IV-TR Axis I disorder other than major depressive disorder within 6 months prior to the study
• Diagnosis of a DSM-IV-TR Axis II disorder that was considered to have a major impact on the patient's current psychiatric status
• A history of substance or alcohol abuse or dependence excluding caffeine and nicotine
• Patients who were unable to abstain from drugs that induce or inhibit the drug-metabolizing enzyme CYP3A4 from 14 days prior to the start of study drug administration and throughout the study period
• Pregnant or lactating women
• Patients showing evidence or signs of renal or hepatic failure, serious heart disease, cerebrovascular disease, viral hepatitis B or C, or acquired immunodeficiency syndrome (AIDS) (carrier)
• A clinical finding that in the opinion of the investigator/sub-investigator could be negatively affected by the study or that would affect the study results (e.g., hypertension, unstable angina)
• Conditions that could affect absorption and metabolism of the study medication (e.g., malabsorption syndrome, liver disease)
• A current diagnosis of malignant tumor unless in remission for at least 5 years (except basal or squamous cell skin carcinoma)
• A current or past diagnosis of transient ischemic attack (TIA)
• A history of seizure disorder, except for febrile convulsions
• Application of electroconvulsive therapy within 90 days prior to the start of study drug administration
• Use of a depot antipsychotic injection and inability to be off the drug for a period of twice the dosing interval prior to the start of study drug administration and throughout the study period
• Patients could require psychotherapy (other than supportive psychotherapy) during the study period, unless psychotherapy had been ongoing for a minimum of 90 days prior to the start of study drug administration
• A score of ≥ 3 on the HAM-D17 Item (suicide) or a suicide attempt within the past 6 months, and those judged to be at serious suicidal or homicidal risk in the opinion of the investigator/sub-investigator
• A current or past history of diabetes mellitus* or glycated hemoglobin (HbA1c) of ≥ 6.5% at screening within 2 months before the start of study drug administration (*refer to the guidelines for monitoring blood glucose levels in patients treated with atypical antipsychotics)
• A white blood cell count (WBC) of ≤ 3,000/mm3 at screening assessment
• Elevation of aspartate aminotransferase (AST) or alanine aminotransferase (ALT) values at screening assessment (grade 2 or higher according to the "Criteria for Classification of the Grade of Adverse Drug Reactions to Pharmaceutical Products" (Pharmaceutical Affairs Bureau Safety Division's Notification No. 80 issued on 29 June 1992))
• A known history of hypersensitivity to quetiapine or to any other component in the FK949E tablets at the time of providing written informed consent
• Treatment with quetiapine for depressive symptoms or bipolar disorder (mania) at the time of providing written informed consent
• Participation in another clinical study or post-marketing study within 12 weeks prior to the start of study drug administration