Protein Kinase C (PKC) plays a major role in the regulation of both pre and postsynaptic neurotransmission. Excessive activation of PKC results in symptoms related to bipolar disorder. PKC exists as a family of closely related subspecies, has a heterogeneous distribution in the brain (with particularly high levels in presynaptic nerve terminals), and plays a crucial role in the regulation of neuronal excitability, neurotransmitter release, regulation of synaptic plasticity and various forms of learning and memory. Research findings show that the PKC pathway can be used as a target for developing treatment strategies for bipolar disorder. Endoxifen exhibited activity in inhibiting the PKC activity.

In patients with acute bipolar mania, rapid reduction of symptoms is a key treatment goal; however, there is also a need for effective maintenance of effect treatment beyond the period of acute stabilization. The current study will evaluate the efficacy and safety of Endoxifen in Bipolar I Disorder patients against a control placebo arm.