Effectiveness of Pramipexole for Treatment-Resistant Depression

Inclusion Criteria: Meets diagnostic criteria for major depressive disorder Meets criteria for current major depressive episode Score of at least 18 on the Montgomery-Asberg Depression Rating Scale (MADRS) at the baseline visit Currently being treated with antidepressant monotherapy at an adequate dose for 6 weeks or willing to enter open lead-in treatment Agrees to use an effective form of contraception throughout the study Exclusion Criteria: Pregnant At risk for suicide or homicide Unstable medical illness (e.g., cardiovascular, liver, kidney, respiratory, endocrine, or neurologic disease, including uncontrolled seizure disorder) History of a substance use disorder within 6 months of study enrollment History of or current psychotic features Currently being treated with typical or atypical antipsychotic medications Currently being treated with a medication known to significantly decrease pramipexole clearance (e.g., cimetidine, ranitidine, diltazem, verapamil, quinine or triamterene) Clinical or laboratory evidence of untreated hypothyroidism History of a 2-week or longer course of pramipexole Intolerance of pramipexole at any dose Any investigational psychotropic drug use within the last three months Level 3 or greater antidepressant resistance as assessed by the ATHF Three or more episodes of self-harm in the year prior to study enrollment Documented history of poor treatment adherence or frequently missed appointments Parkinson's disease