Does Enhanced Glutamate Transporter Function Produce Antidepressant Effects in People With Major Depression?

Study Summary

Background: \- At least one third of individuals with major depressive disorder (MDD) remain treatment-refractory after receiving currently available antidepressants underscoring the urgent need for new antidepressant therapies. Of the novel pharmacotherapeutic strategies seeking to rapidly alleviate depressive symptoms, glutamatergic modulators have emerged as promising potential targets. The present study sought to examine the potassium (KATP) channel activator diazoxide as a possible treatment for MDD. Diazoxide increases glutamate uptake from the synaptic cleft by activating the KATP channel to chronically increase expression of the excitatory amino acid transporter (EAAT)-2 system in glial cells. Diazoxide is FDA-approved for the treatment of sulfonylurea-induced hypoglycemia, hypoglycemia due to hyperinsulinemia, and hypertension. Objectives: \- To assess the ability of diazoxide, potassium channel activator, to improve overall depressive symptomatology in patients with treatment-resistant MDD currently experiencing a major depressive episode. The efficacy of a three-week course of diazoxide will be compared to three weeks of placebo. The MADRS will serve as the main outcome measure Eligibility: \- Adults 18 to 65 years old with MDD who are currently depressed without psychotic features. Design: * Study Phase I (Day -28 to 0): \-- Screen and taper off medications (Days -28 to -14): Prior to consenting to this study, subjects will have undergone a screening consisting of laboratory tests, psychiatric and medical history, and psychiatric and physical examinations under protocol 01-M-0254, "The Evaluation of Patients with Mood and Anxiety Disorders and Healthy Volunteers". After consenting to this study, patients will be tapered off medications. Medications allowed and not allowed are listed in Appendix 1. Patients will be reminded to report all drugs, OTC products, and other agents to the investigators so that they can screen to avoid interactions that

Primary Outcome

Change in Montgomery Asberg Depression Rating Scale (MADRS) from baseline to 7 days post-treatment. The range of values is from 0 - 60, with a higher score indicating increased depressive symptoms. A score of 7-19 indicates mild depression; 20-34 indicates moderate depression; \>34 indicates severe depression.

Interventions

• DRUG Placebo
• DRUG Diazoxide