Recruitment was stopped before the planned sample size was reached owing to the Covid-19 pandemic and expiration of funding.

Patients with bipolar I disorder (BD) experience depression 3 times more frequently than mania, and antidepressants are prescribed as adjuncts to mood stabilizers in up to 70% of patients. However, no placebo-controlled trials have assessed the efficacy or safety of modern antidepressants in combination with mood stabilizers in the maintenance treatment of BD. The investigators propose a multicentre, randomized, double-blind clinical trial comparing mood stabilizer plus antidepressant (escitalopram or bupropion XL) to mood stabilizer plus placebo in the maintenance treatment of BD.

The investigators hypothesize that in clinically representative patients with bipolar disorder, who respond to acute treatment with a newer antidepressant medication in conjunction with a mood stabilizing medication, continuing the antidepressant for 12 months will reduce the risk of relapse into any mood episode, including depression, mania, and hypomania, compared to stopping the antidepressant after 8 weeks.

Study Design:

The investigators propose a multicentre, randomized, double-blind, placebo-controlled trial in patients with BD who are currently experiencing a depressive episode. The trial will consist of two phases: an open-label acute treatment phase, and a double-blind maintenance treatment phase.

OPEN-LABEL ACUTE TREATMENT PHASE

Experimental Design Patients with BD depression who are receiving treatment with antimanic medication(s), defined as: 1) a mood stabilizer (lithium or divalproex ), 2) a second-generation antipsychotic (SGA) (risperidone, olanzapine, quetiapine, aripiprazole, or ziprasidone), or 3) combination anti-manic therapy (two mood stabilizers; or a mood stabilizer plus an SGA (the SGA asenapine will also be permitted if prescribed with a mood stabilizer); or a mood stabilizer or SGA plus lamotrigine), will have open-label escitalopram 10-30 mg/day or bupropion XL 150-450 mg/day added to their medication(s) for up to 16 weeks.Patients who complete at least 4 weeks of treatment and achieve remission from their index depression which is maintained for ≥ 2 weeks will be eligible to enter the double-blind study phase. The duration of treatment in the open-label phase will be 4-16 weeks, depending on the time required to achieve remission.

DOUBLE-BLIND MAINTENANCE TREATMENT PHASE

Patients who are in remission from their index depression for ≥ 2 weeks and ≤ 8 weeks are eligible to take part in the double-blind maintenance phase. There are two routes to enter the double-blind phase:

• following completion of the open-label phase, or
• following a period of clinical treatment, not exceeding 16 weeks, with the same medications used in the open-label phase. Patients who respond to clinical treatment with carbamazepine plus an antidepressant may also enter the double-blind phase.

Experimental Design

During the double-blind phase, all patients will continue treatment with their anti-manic medication(s) and will be randomized to one of two treatment arms for up to 52 weeks:

• Patients randomized to the "8 week arm" will discontinue antidepressant treatment after 8 weeks, as recommended in current clinical practice guidelines..
• Patients randomized to the "52 week arm" will continue treatment with their antidepressant medication for 52 weeks, or until withdrawal from the study.

Inclusion Criteria:

OPEN-LABEL ACUTE TREATMENT PHASE

1. Diagnosed with BD, current episode depressed, with a MADRS score ≥ 20 at both the screening and baseline assessments
2. The duration of the current depressive episode is ≥ 2 weeks but ≤ 52 weeks
3. Taking or initiating treatment with an anti-manic medication at a therapeutic dose. Anti-manic medications and therapeutic doses are: lithium, serum level 0.6-1.4 mEq/L; divalproex, serum level 350-700 mM; risperidone 1-6 mg/day; olanzapine 5-30 mg/day; quetiapine IR or XR 300-900 mg/day; aripiprazole 10-30 mg/day; and ziprasidone 80-160 mg/day. 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.
4. If taking any other psychoactive medication (other than lorazepam ≤ 4 mg/day or equivalent), is agreeable to tapering and discontinuing it over a period of ≤ 4 weeks
5. If female and of childbearing potential, is using an adequate method of contraception.
6. Aged 18-70 years, inclusive
7. Fluent in English and capable of providing informed consent

DOUBLE-BLIND MAINTENANCE TREATMENT PHASE

• Patients meeting all of the following criteria will be eligible to be included in the double-blind study phase:

1. Taking escitalopram 10-30 mg/day or bupropion XL 150-450 mg/day, in addition to their anti-manic medication.
2. Has adequately tolerated the combination of antidepressant plus mood stabilizer, and is currently in remission for ≥ 2 weeks and ≤ 8 weeks
3. If female and of childbearing potential, is using an adequate method of contraception

Exclusion Criteria:

OPEN-LABEL ACUTE TREATMENT PHASE

1. Has a history of rapid cycling, defined as ≥ 4 mood episodes in the preceding 12 months
2. Has current manic, hypomanic, or subsyndromal hypomanic symptoms, defined as a Young Mania Rating Scale (YMRS) score ≥ 8 at the screening or baseline visits
3. Has previously been refractory to treatment with both escitalopram and bupropion XL, or has been unable to tolerate both medications due to intolerable side effects or an allergic reaction
4. Is taking monoamine oxidase inhibitors, such as phenelzine or tranylcypromine
5. Escitalopram is contraindicated in patients taking pimozide or ziprasidone. Patients on pimozide or ziprasidone can participate in the study and will be prescribed bupropion XL
6. Bupropion XL is contraindicated in patients taking other preparations containing bupropion, in patients with active eating disorders, including anorexia nervosa and bulimia nervosa; and in patients with seizure disorders. Patients with any of these can still participate in the study and will be prescribed Escitalopram
7. Has active substance dependence, other than caffeine or nicotine dependence, in the preceding 3 months. Otherwise, patients with comorbid substance abuse or other comorbid psychiatric illnesses will be eligible to participate in the study
8. Is at high risk for suicide, as defined by a score of ≥ 4 on the suicide item of the MADRS, or in the opinion of the investigator
9. Has an unstable medical illness, as defined by a change in medication or other treatment in the past 4 weeks, or in the opinion of the investigator
10. Has significant abnormalities on an electrocardiogram
11. Is pregnant or lactating

DOUBLE-BLIND MAINTENANCE TREATMENT PHASE

1. Has a history of rapid cycling, defined as ≥ 4 mood episodes in the preceding 12 months
2. Has current manic, hypomanic, or subsyndromal hypomanic symptoms, defined as a YMRS score ≥ 8 at the screening or baseline visits
3. Has active substance dependence, other than caffeine or nicotine dependence, in the preceding 3 months. Otherwise, patients with comorbid substance abuse or other comorbid psychiatric illnesses will be eligible to participate in the study
4. Is at high risk for suicide, as defined by a score of ≥ 4 on the suicide item of the MADRS, or in the opinion of the investigator
5. Has an unstable medical illness, as defined by a change in medication or other treatment in the past 4 weeks, or in the opinion of the investigator.
6. Has significant abnormalities on an electrocardiogram
7. Is pregnant or lactating
8. Has experienced an episode of mania, hypomania, or a mixed episode during antidepressant treatment of the acute depression, defined as a YMRS score of ≥ 16 at any open-label study visit, or in the opinion of the study psychiatrist

Some participants who took part in the Open Label Phase were then included in the Double Blind portion of the study therefore certain participants are represented more than once in the Total Arm/Group.

Final analysis 8 week arm - 87 participants. Excluded one participant due to missing baseline and follow-up data.

52 week arm - 90 participants.

4- 16 weeks on the open-label phase and up to 1 year for each participant in the double-blind phase.

The open-label phase includes adverse events experienced from the 206 participants analyzed in that phase.

The double-blind phase includes adverse events experienced from the 177 participants analyzed in that phase.

Recruitment was stopped before the planned sample size was reached owing to the Covid-19 pandemic and expiration of funding.