Adjunct Minocyline in Treatment-resistant Depression

This is a double-blind, placebo-controlled, randomized, multicenter proof-of-principle trial of adjunctive minocycline for patients with unipolar major depressive disorder (MDD). The study tests the antidepressant efficacy of minocycline as an adjunct to an antidepressant standard treatment (AD-ST), for patients with unipolar major depressive disorder (MDD). The respective AD, for which non-response has been documented, must be on a stable regimen for at least 14 days prior to inclusion. AD-ST will then be continued throughout the trial. Trial medication is adjunct oral minocycline 200 mg/day or placebo. Response to treatment will be measured via the Montgomery-Asberg Depression Rating Scale (MADRS). The total study duration for each patient will be 6 weeks.