Cannabidiol for Bipolar Depression (CBD-BD) (CBD-BD)

Inclusion Criteria: Males or females aged 19 to 70 years (inclusive). Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnosis of Bipolar Disorder Type I or Type II, AND a current major depressive episode. All patients must be taking either a mood stabilizer (i.e. lithium or valproate; lamotrigine monotherapy as a mood stabilizer is acceptable for BD II patients only and not for BD I) OR an atypical antipsychotic OR a combination of these (two mood stabilizers or a mood stabilizer plus an atypical antipsychotic), at therapeutic doses. Combinations of these medications as outlined above, or the combination of any of them with lamotrigine 100-400 mg daily, or the combination of a mood stabilizer plus asenapine 5-20 mg/day are also permitted. Have received a minimum of 6-weeks treatment at adequate doses for treatment of current depressive episode with at least one CANMAT recommended first-line treatment for bipolar I disorder (i.e. lithium, lamotrigine, lurasidone, or quetiapine either as monotherapy or adjunctive therapy), or at least one first or second-line treatment for bipolar II depression (i.e. quetiapine, lithium, lamotrigine, sertraline, or venlafaxine as monotherapy or adjunctive therapy, or bupropion adjunctive therapy). A MADRS score of ≥ 20 and a YMRS score of ≤ 12. Inpatient or outpatient status. Females of childbearing potential are required to take contraceptive pills OR agree to practice effective double barrier methods of contraception OR agree to completely abstain from heterosexual intercourse. Females who do not have childbearing potential are required to be postmenopausal for at least 1 year before the screening visit (confirmed by an FSH test) OR surgically sterile. The capability of understanding, consenting to and complying with study requirements. All concomitant medication must be at a stable dose for two weeks prior to the randomization visit. Exclusion Criteria: Current depressive episode greater than 6 months. A history of rapid cycling, defined as ≥ 4 mood episodes in the preceding 12 months. Current unstable or inadequately treated medical illness with the exception of current depression. A history of non-response or intolerance to CBD. Current or past month daily use of CBD, or any product or drug that contains CBD. Occasional users will be included if they agree to refrain from using during the trial. A history of non-response to electroconvulsive therapy. A current diagnosis of other primary psychiatric disorders as assessed by a study investigator to be primary and causing greater impairment than BD. A lifetime history of a primary psychotic disorder (e.g. schizoaffective disorder, bipolar subtype) according to DSM-5 criteria. Patients who have met the DSM-5 criteria for a substance use disorder (except for nicotine or caffeine) within the past 6 months. Significant active suicidal ideation (as evidenced by MADRS suicide item ≥ 4). Pregnancy or lactation. Liver function tests (AST and ALT) three times the upper limit of normal.