Antidepressant Effects of NR2B in Major Depression
Condition: Major Depression
MeSH terms: Depression; Depressive Disorder; Depressive Disorder, Major
Study type: Interventional
Phase: Phase 1

Summary: 
      Purpose : This study will determine whether MK-0657, a selective NR2B Antagonist, can quickly
      improve symptoms of depressed mood, psychomotor retardation, poor motivation and reduced
      enjoyment of things in patients with major depression.

      MK-0657 decreases the activity of a brain receptor called NMDA, which the chemical glutamate
      binds to, possibly inducing a rapid antidepressant response. People between 18 and 55 years
      of age who have major depression of at least 4 weeks' duration and have not been helped by
      two antidepressants approved for major depression may be eligible for this study. Women who
      are able to have children are excluded. Participants are admitted to the NIH Clinical Center
      for two study phases, as follows. Phase I (1 to 2 weeks): Patients are tapered off their
      current medications. Phase II (7 weeks): Patients are randomly assigned to take either
      MK-0657 or placebo (look-alike capsules with no active ingredient) by mouth for 12 days. At
      some point during the second part this phase, patients who had been taking MK-0657 are
      switched over to placebo and those who had been taking placebo are switched to MK-0657.
      Participants undergo the following procedures during the study:Physical examination twice (at
      the beginning and at the end of the study) Electrocardiogram (ECG) four times Blood tests
      about six times Rating scales up to 28 times to assess the effects of MK-0657 on mood and
      thinking Blood pressure measurements three times a day.

      Study examines the effectiveness of a new medication, targeting a system called glutamate,
      will improve depression when compared with placebo.
    

Detailed description: 
      Even though there are many antidepressant drugs for clinical use, clinical trials indicate
      that 30% to 40% of patients with major depression fail to respond to first-line
      antidepressant treatments despite adequate dosage, duration, and compliance. Furthermore,
      these medications may take weeks to months to achieve their full effects and in the meantime,
      patients continue to suffer from their symptoms and be at risk of self-harm as well as harm
      to their personal and professional lives. Thus, there is a clear need to develop novel and
      improved therapeutics for treatment-resistant major depression that have a rapid onset of
      action. Recent preclinical studies suggest that antidepressants may exert delayed indirect
      effects on the glutamatergic system, specifically on the NMDA receptor complex. A recent
      study by our group found that a single intravenous dose of the non-competitive NMDA
      antagonist ketamine produced a rapid, robust and relatively sustained antidepressant effect
      in patients with treatment-resistant major depression. Together, these data suggest that the
      NMDA receptor may play an important role in the mechanism of antidepressant action.
      Unfortunately, ketamine's psychotomimetic effects preclude its use as a chronic
      antidepressant; these side effects probably are a result of ketamine's effects on multiple
      NMDA subunits. Thus, studying selective NMDA subunit antagonists in depression is a
      reasonable next step. The NR2B subunit stands as a prime candidate to test in depression.
      Preclinical data by our group indicates that the NR2B subunit is involved in the mechanism of
      antidepressant action as indicated by changes in phosphorylation of serine residues in the
      learned helplessness model of depression and with chronic treatment with imipramine. In
      addition, we found that the NR2B antagonist R0 25-6981 has antidepressant-like properties in
      the forced swim test. We propose to examine whether the selective NR2B antagonist (MK-0657)
      produces rapid antidepressant effects in patients with treatment-resistant major depression
      but without causing psychotomimetic effects.

      Male and female patients, ages 18 to 55 years, with a diagnosis of major depression (without
      psychotic features), will be recruited for this study. This study consists of the
      double-blind crossover administration of either the NR2B antagonist MK-0657 (4-8 mg/day) or
      placebo.

      The specific aim of this study is to assess the efficacy of 12 days of a selective NR2B
      antagonist (MK-0657, 4-8 mg/day given orally) compared with placebo in improving overall
      depressive symptomatology in patients with treatment-resistant major depression.

      Our primary hypothesis is that subjects with treatment-resistant major depression who are
      randomized to a selective NR2B antagonist (MK-0657) will have a more rapid and superior
      response compared to when they are randomized to placebo. This is a proof of concept and
      treatment study.

      Approximately, 27 subjects will be randomized; the accrual ceiling for this protocol is 60
      subjects.
    

Intervention name(s): MK-0657; Placebo
Intervention type(s): Drug; Drug
Intervention description(s): Daily double-blind administration of the NR2B antagonist MK-0657 (4-8 mg/day); Daily double-blind administration of placebo
Other intervention name(s): NR2B antagonist; Inactive drug
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: NMDA Receptor; Depression Treatment; Unipolar Depression; Treatment Resistant; Glutamatergic; Depression; Major Depression