Add-on Buprenorphine at Analgesic Doses for the Treatment of Severe Suicidal Ideas During a Major Depressive Episode

Participants will be randomized to two doses of buprenorphine (0.4mg and 0.8mg) or placebo. The duration of treatment will be 21 days with 7 days withdrawal period. Two follow‐up phone calls at 3 and 6 months will investigate occurence of suicidal behavior. The main outcome will be changes in suicidal ideas levels during the first week. Secondary outcomes will be changes in suicidal ideas during the following 21 days, changes in depression and psychological pain levels over the first 28 days, dropout rates, reasons and occurence of side effects over the first 28 days, withdrawal symptoms dung the withdrawal period, changes in neuropsychological and neuroimaging measures between Day 0 and Day 28. Blood and stool samples will be collected at 4 time points and stored in a biobank for future analyses.