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

Inclusion Criteria: * The patient has been correctly informed. * The patient must have given his/her informed and signed the consent form. * The patient must be insured or beneficiary of a health insurance plan. * The patient is at least 18 years old and 65 years old at the most. * The patient is hospitalized or followed in consultation. * The patient has a current major depressive episode without psychotic features according to the criteria of the "Diagnostic and Statistical Manual of Mental Disorders" * The patient has a score \> 20 of the "Montgomery-Asberg Depression Rating Scale". * The patient has a current Scale for Suicidal Ideation (SSI) score \> 8. Exclusion Criteria: * The patient is participating in another interventional trial; * The patient is in an exclusion period determined by a previous study; * The patient is under judicial protection, or is an adult under guardianship; * The patient is under compulsory admission; * The patient refuses to sign the consent; * it is impossible to correctly inform the patient. * The patient is pregnant or breastfeeding. * The patient suffers from schizophrenia; * The patient suffered from moderate to severe alcohol use disorder or substance use disorder (except tobacco and caffeine) over the last 12 months according to DSM-5 criteria ; * The patient currently suffers from severe and/or unstable medical condition (including severe respiratory or hepatic insufficiency) or a painful medical condition; * The patient has a current known sleep apnea. * The patient currently takes analgesic treatment (including Nonsteroidal anti-inflammatory drug and paracetamol); * The patient currently takes central nervous depressant drugs at sedative doses (based on the investigator's assessment), including benzodiazepines, antihistamines, and sedative antipsychotics; * The patient currently takes major CYP3A4 Inhibitors and inducers; * The patient currently takes has received Electroconvulsivotherapy over the last 3 months.