Evaluate Efficacy and Safety of Endoxifen in Bipolar I Disorder Patients

Inclusion Criteria:

1. Male and female patients, 18 to 65 (both inclusive) years of age willing to givewritten informed consent along with at least one first degree relative (the legallyacceptable representative [LAR]) to participate in the study before initiating anystudy related procedures.

2. Patients must have a diagnosis of bipolar I disorder and currently display an acutemanic episodes with or without mixed features according to DSM-5 criteria as judgedby the Investigator.

3. Young Mania Rating Scale (YMRS) total score of > 20 and ≥4 on two of four core items (irritability, speech, content, disruptive/aggressive behavior) at screening and atrandomization (baseline).

4. Score of >4 in Severity of illness criteria of Clinical Global Impressions- bipolardisorder (CGI-BP) Scale for overall illness at screening and at randomization (baseline).

5. Ready for voluntary hospitalization (along with the accompanying LAR if required andas advised by the Investigator) for the current manic episode 2 days prior torandomization up to 21 days of in-patient treatment period.

6. Last intake of the medication(s) for BPD should be 2-7 days prior to randomizationdepending upon the individual drug's plasma half-life.

7. Patient and / or LAR understand and agree to comply with all the study requirements.

8. Male patients of child begetting potential must be practicing adequatecontraception.

9. Females of reproductive potential (which include girls who have entered puberty andall women who have a uterus and ovaries and have not completed menopause), must useanacceptable and effective method of avoiding pregnancy, starting at least fourweeks before the first dose of study drug and continuing until at least one monthafter the last dose of study drug.

10. Subjects judged clinically not to be at serious suicide risk.

Exclusion Criteria:

1. Newly diagnosed patients and not having any suitable treatment exposure in the pastfor their bipolar mood disorder.

2. > 20% improvement in YMRS total scores between screening and randomization visits.

3. Patients who meet DSM-5 criteria for any psychiatric disorder other than Bipolar IDisorder with Acute Mania Episode with or without mixed features.

4. Patients with seizure disorder.

5. Obsessive compulsive disorder or any other co-morbid Axis I anxiety disorder

6. Patients with borderline or anti-social personality disorder of sufficient currentseverity to interfere with conduct of the study

7. Patients with classical premenopausal symptoms found at risk of developingintolerable hot flushes, irregular vaginal bleeding.

8. Use of the following medications:

• Antihypertensive agents if stable dose has not been administered for at least 1month before randomization

• Antidepressants in the week (or a period of 5 half-lives of the drug) prior torandomization

• Continuous daily or standing orders use of benzodiazepines during the monthpreceding screening (approximately 5 weeks prior to screening)

• Potent cytochrome P450 (CYP) inducers and CYP2D6/CYP3A4 inhibitors 14 daysprior to randomization

• Depot antipsychotic medications within 1 dosing interval prior to randomization

• Use of systemic estrogens 6 weeks prior to randomization

• Patients currently on carbapenem agents

9. Any of the following laboratory abnormalities

• Serum bilirubin ≥ 1.5 times ULN

• Serum AST/ALT ≥ 2.5 times ULN

• Serum TSH >10% above the ULN, regardless of treatment for hypothyroidism orhyperthyroidism

• Serum triglyceride level > 2.5 times ULN

10. Patients with the following cardiac conditions are excluded:

• Recent myocardial infarction (<12 months)

• QTc prolongation (screening electrocardiogram with QTc >450 msec for men, QTc> 470 msec for women)

• History of QTc prolongation or using concomitant medications (as judged by theInvestigator) which prolong QTc interval

• Sustained cardiac arrhythmia or history of sustained cardiac arrhythmia

• De compensatory congestive heart failure

• Complete left bundle branch block

• First-degree heart block with PR interval > 0.22 seconds

11. Presence of a coagulation disorder; active or past history of venous thromboembolismincluding deep venous thrombosis or pulmonary embolism.

12. Current prolonged immobilization.

13. History or current presence of retinal pathology including retinal vein thrombosis

14. Increased risk of stroke as per the Investigator's discretion.

15. History of hypersensitivity or intolerance to tamoxifen or any other ingredients ofthe preparation.

16. Serious, unstable illnesses including hepatic, renal, gastroenterologic,respiratory, cardiovascular (including ischemic heart disease), endocrinologic,neurologic, immunologic, or hematologic disease as per history and medicalexamination.

17. Drug screen positive for any drug of abuse at screening (with the exception ofbenzodiazepines used in therapeutic dose for management of acute mania), activesubstance abuse in the past 2 months or history of substance dependence (excludingnicotine and caffeine) within 3 months of screening.

18. History of breast or uterine cancer, or abnormal uterine bleeding.

19. Current leukopenia or thrombocytopenia as judged by the Investigator in the besthealth interest of the subject.

20. Clinically significant suicidal or homicidal ideation.

21. Participation in a clinical trial of another investigational drug within 30 daysprior to screening.