The present invention provides compositions containing endoxifen, formulations and liposomes of endoxifen, methods of preparation of such agents and formulations, and use of such agents and formulations for the treatment of a subject having or at risk for psychiatric and neurodegenerative diseases. Specifically, the present invention relates to the composition comprising endoxifen in the treatment of bipolar disorder, schizophrenia, multiple sclerosis (MS), Alzheimer disease, Parkinson disease, Huntington's disease, amyotrophic lateral sclerosis (ALS), and/or epilepsy by administrating formulations or compositions comprising an effective amount of endoxifen.