Civilization diseases are one of the greatest health problems affecting both highly developed as well as rapidly developing countries. In a medical sense, depression is treated as a serious illness manifesting itself with a decrease in mood and activity for a prolonged periods of time. Bipolar depression is a highly disabling and causes marked occupational and social impairment. The efficacy of antidepressants in the treatment of bipolar depression remains unclear.

The primary objective of the study is to determine the efficacy and dose response of Esketamine, administered by inhalation from Dry powder Inhaler, compared with placebo, in subjects with treatment resistant bipolar depression, as assessed by change from baseline in the MADRS total score at Day 14 of treatment phase.

Results of this study, named "A multicentre, double-blind, randomised, placebo - controlled phase II study to assess efficacy, safety and pharmacokinetics of inhaled Esketamine in subject with treatment-resistant bipolar depression", will be used to provide further evidence of efficacy and safety of Celon Pharma's Esketamine administered by inhalation from Dry Powder Inhaler to patients with treatment resistant bipolar depression.