This is a phase 2 and 3 adaptive design study for Mitizodone Phosphate,to find out an optimal dose in phase 2 period and confirm the result an efficacy and safety in phase 3 period.Dose-finding will be done after 8 weeks of double-blinded treatment in phase 2 period and will be assessed by both efficacy and safety from 3 dose groups of Mitizodone Phosphate.The dose be found in phase 2 period will be evaluated on efficacy and safety when compared with placebo in phase 3 period with a duration of 8 weeks treatment.The target subjects are patients with MDD.
1.a Man or a woman with major depressive disorder(MDD) as the primary diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria (classification code 296.22、296.23、296.32、296.33)
2.Has a Montgomery Åsberg Depression Rating Scale (MADRS) total score of 26 or greater at Screening and Baseline Visits.
3.Has a Clinical Global Impression - Severity of Illness (CGI-S) score of 4 or greater at Screening and Baseline Visits.
1.has major depressive disorder with psychotic features according to the DSM-5.
2.Current or history of: bipolar disorder、schizophrenia、anixety disorder、insomnia、any substance abuse or dependence and other psychiatry disorder as defined in the DSM-5.
3.Current or history of a clinically significant neurological disorder (including epilepsy、Alzheimer disease, Parkinson disease, multiple sclerosis, Huntington disease).
4. has Serious body disease such as neurological disorders、cardiacvascular disorders、hepatic disorders、 renal disorders, blood system disorders and endocrine disorders.