Does Enhanced Glutamate Transporter Function Produce Antidepressant Effects in People With Major Depression?
| Status: | Terminated |
|---|---|
| Conditions: | Depression, Depression, Major Depression Disorder (MDD) |
| Therapuetic Areas: | Psychiatry / Psychology, Pulmonary / Respiratory Diseases |
| Healthy: | No |
| Age Range: | 18 - 65 |
| Updated: | 10/15/2017 |
| Start Date: | January 3, 2014 |
| End Date: | July 21, 2016 |
A Pathophysiological Study to Determine if Enhancing Glutamate Transporter Function Produces Antidepressant Effects in Patients With Major Depressive Disorder
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 might make participation unsafe or might
confound the research results. Patients are expected to meet all inclusion and exclusion
criteria before medications are tapered (which is usually 1-2 weeks long). Subjects who
are not taking medications will enter the drug-free period directly. All participants
must have a score of ≥20 on the MADRS at screening and baseline of Study Phase I.
Subjects who do not have a score of ≥20 on the MADRS by the end of Study Phase I will be
excluded and will receive standard treatment.
- Drug-free period (Day -14 to day 0):
-- Subjects will begin a 2-week drug-free period prior to the administration of
diazoxide or placebo.
- Study Phase II (Day 0 to 56):
- In this study phase, subjects will be blindly randomized to receive either
diazoxide 200-400 mg/day (given BID) or a placebo administered daily by mouth for
three weeks. All patients except those who have a 50% or greater decrease in MADRS
from baseline at the end of the first cross over point will cross over. To avoid
carry-over effects between the different test sessions, there will be an interval
of 14-21 days, pending response to test session 1. Subjects will then be blindly
crossed over to the second experimental condition (either diazoxide or placebo) for
another three weeks. All subjects who discontinue the study or who complete study
phase II will then receive either clinical treatment or the opportunity to
participate in another research protocol. Patients maintaining response to
treatment condition 1 after two weeks will receive an additional one week washout
before being crossed over to condition 2.The total duration of the study is
approximately 11-13 weeks. The duration of Study Phase I including the 14-day
drug-free period is approximately 4 weeks. Study phase II is 8-9 weeks long. Thus,
the total duration of the study is approximately 11-13 weeks, except for those
patients who were unmedicated at time of entry into the study and therefore do not
need to undergo the initial tapering off medications. Subjects will be required to
be hospitalized during the entire study. Passes will be permitted if the subject is
clinically stable and the pass does not interfere with the study or unit
procedures.
- 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 might make participation unsafe or might
confound the research results. Patients are expected to meet all inclusion and exclusion
criteria before medications are tapered (which is usually 1-2 weeks long). Subjects who
are not taking medications will enter the drug-free period directly. All participants
must have a score of ≥20 on the MADRS at screening and baseline of Study Phase I.
Subjects who do not have a score of ≥20 on the MADRS by the end of Study Phase I will be
excluded and will receive standard treatment.
- Drug-free period (Day -14 to day 0):
-- Subjects will begin a 2-week drug-free period prior to the administration of
diazoxide or placebo.
- Study Phase II (Day 0 to 56):
- In this study phase, subjects will be blindly randomized to receive either
diazoxide 200-400 mg/day (given BID) or a placebo administered daily by mouth for
three weeks. All patients except those who have a 50% or greater decrease in MADRS
from baseline at the end of the first cross over point will cross over. To avoid
carry-over effects between the different test sessions, there will be an interval
of 14-21 days, pending response to test session 1. Subjects will then be blindly
crossed over to the second experimental condition (either diazoxide or placebo) for
another three weeks. All subjects who discontinue the study or who complete study
phase II will then receive either clinical treatment or the opportunity to
participate in another research protocol. Patients maintaining response to
treatment condition 1 after two weeks will receive an additional one week washout
before being crossed over to condition 2.The total duration of the study is
approximately 11-13 weeks. The duration of Study Phase I including the 14-day
drug-free period is approximately 4 weeks. Study phase II is 8-9 weeks long. Thus,
the total duration of the study is approximately 11-13 weeks, except for those
patients who were unmedicated at time of entry into the study and therefore do not
need to undergo the initial tapering off medications. Subjects will be required to
be hospitalized during the entire study. Passes will be permitted if the subject is
clinically stable and the pass does not interfere with the study or unit
procedures.
Objective:
To date, available pharmacological treatments for major depressive disorder (MDD) have proven
to be only modestly effective during the acute phase. We have been systematically testing
different glutamatergic modulators in patients with mood disorders in order to develop
improved therapeutics. A recent report found that the (beta)-lactam antibiotic ceftriaxone
increased glutamate uptake by increasing GLT1(EAAT2) function and had antidepressant-like
effects in animal models. Using the learned helplessness model of depression we developed
outbred lines, defined a new anatomy of helplessness, and determined that synaptic loss due
to excess extracellular glutamate appears to be involved in the pathophysiology of
helplessness; these animals show a 40% decrease in EAAT2 astrocytic transporter expression.
Together, these data suggest that astrocytic glutamate reuptake systems may be central to the
pathophysiology and treatment of depression, and that agents that directly increase
astrocytic glutamate uptake may represent a novel class of antidepressants.
With this protocol, we propose to test a specific new mechanism that uses diazoxide to
chronically increase expression of the glutamate transporter EAAT2, resulting in removal of
glutamate from the synaptic cleft. Diazoxide enhances glutamate uptake in glia by activating
ATP-sensitive potassium (KATP) channels. We expect that this effect will reduce excessive
glutamate transmission and be associated with acute antidepressant effects. The model
presented here is a clinically testable one. If successful, it may lead to the development of
a group of novel pharmacological treatments for major depressive disorder.
Study Population:
24 individuals with treatment-resistant major depressive disorder.
Design:
Male and female patients diagnosed with MDD, ages 18 to 65 years, currently experiencing a
major depressive episode, will be recruited for this study. The study will comprise the
double-blind crossover administration of either diazoxide (200-400 mg/day given orally) or
placebo. The study will assess the efficacy of three weeks of a glutamate transporter
enhancer (diazoxide, 200-400 mg/day given orally) compared with placebo in improving overall
depressive symptomatology in patients with treatment-resistant MDD. Other aims of the study
include: 1) determining whether changes in brain neurochemicals (glutamate) correlate with
antidepressant response (as measured by decreases in Montgomery-Asberg Depression Rating
Scale (MADRS) total scores) in response to diazoxide in patients with treatment-resistant
MDD; and 2) examining other potential biomarkers of response.
Outcome Measures:
Primary: MADRS total score. Secondary outcome measures: proportion of subjects achieving
remission (MADRS score less than or equal to 10) and response (more <50% reduction from
baseline in MADRS total score); change from baseline in Beck Depression Inventory (BDI),
Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HAM-D), Visual
Analog Scale (VAS), and the Columbia Suicide Severity Rating Scale (C-SSRS) total scores.
To date, available pharmacological treatments for major depressive disorder (MDD) have proven
to be only modestly effective during the acute phase. We have been systematically testing
different glutamatergic modulators in patients with mood disorders in order to develop
improved therapeutics. A recent report found that the (beta)-lactam antibiotic ceftriaxone
increased glutamate uptake by increasing GLT1(EAAT2) function and had antidepressant-like
effects in animal models. Using the learned helplessness model of depression we developed
outbred lines, defined a new anatomy of helplessness, and determined that synaptic loss due
to excess extracellular glutamate appears to be involved in the pathophysiology of
helplessness; these animals show a 40% decrease in EAAT2 astrocytic transporter expression.
Together, these data suggest that astrocytic glutamate reuptake systems may be central to the
pathophysiology and treatment of depression, and that agents that directly increase
astrocytic glutamate uptake may represent a novel class of antidepressants.
With this protocol, we propose to test a specific new mechanism that uses diazoxide to
chronically increase expression of the glutamate transporter EAAT2, resulting in removal of
glutamate from the synaptic cleft. Diazoxide enhances glutamate uptake in glia by activating
ATP-sensitive potassium (KATP) channels. We expect that this effect will reduce excessive
glutamate transmission and be associated with acute antidepressant effects. The model
presented here is a clinically testable one. If successful, it may lead to the development of
a group of novel pharmacological treatments for major depressive disorder.
Study Population:
24 individuals with treatment-resistant major depressive disorder.
Design:
Male and female patients diagnosed with MDD, ages 18 to 65 years, currently experiencing a
major depressive episode, will be recruited for this study. The study will comprise the
double-blind crossover administration of either diazoxide (200-400 mg/day given orally) or
placebo. The study will assess the efficacy of three weeks of a glutamate transporter
enhancer (diazoxide, 200-400 mg/day given orally) compared with placebo in improving overall
depressive symptomatology in patients with treatment-resistant MDD. Other aims of the study
include: 1) determining whether changes in brain neurochemicals (glutamate) correlate with
antidepressant response (as measured by decreases in Montgomery-Asberg Depression Rating
Scale (MADRS) total scores) in response to diazoxide in patients with treatment-resistant
MDD; and 2) examining other potential biomarkers of response.
Outcome Measures:
Primary: MADRS total score. Secondary outcome measures: proportion of subjects achieving
remission (MADRS score less than or equal to 10) and response (more <50% reduction from
baseline in MADRS total score); change from baseline in Beck Depression Inventory (BDI),
Hamilton Anxiety Rating Scale (HAM-A), Hamilton Depression Rating Scale (HAM-D), Visual
Analog Scale (VAS), and the Columbia Suicide Severity Rating Scale (C-SSRS) total scores.
- INCLUSION CRITERIA:
- 18 to 65 years of age.
- Women of child bearing potential must have a negative serum pregnancy test and
confirmed (by the investigator) use of two effective methods of contraception
(see below).
- Each subject must be capable of understanding all required tests and examinations
and must sign an informed consent document.
- Subjects must fulfill DSM-IV criteria for MDD, single episode or recurrent
without psychotic features, based on clinical assessment and confirmed by a
structured diagnostic interview (SCID-P). Subjects must be experiencing a current
major depressive episode of at least four weeks duration.
- Subjects must have an initial score of at least 20 on the MADRS at screening and
at baseline of study Phase I.
- Subjects must have a current or past history of lack of response to two adequate
antidepressant trials (may be from the same chemical class) operationally defined
using the modified-Antidepressant Treatment History Form (ATHF).
EXCLUSION CRITERIA:
- Current psychotic features or a current or past diagnosis of schizophrenia or any
other psychotic disorder as defined in the DSM-IV.
- Subjects with a history of DSM-IV drug or alcohol dependency or abuse (except for
caffeine or nicotine dependence) within the preceding three months.
- Head injury that results in loss of consciousness exceeding five minutes (for the
imaging component of the study).
- Subjects with a DSM IV Axis II diagnosis of borderline or antisocial personality
disorder.
- Pregnant or nursing women or women of child bearing potential not using two medically
accepted means of contraception (including oral, injectable, or implant birth control,
condoms, a diaphragm with spermicide; intrauterine devices (IUD); tubal ligation;
abstinence; or partner with vasectomy).
- Serious, unstable medical illnesses including hepatic, renal, gastroenterologic,
respiratory, cardiovascular (including ischemic heart disease), endocrinologic,
neurologic, immunologic, or hematologic disease.
- Subjects with hyperthyroidism or clinical hypothyroidism.
- Subjects with one or more seizures without a clear and resolved etiology.
- Clinically significant abnormal laboratory tests (including blood glucose).
- Diabetes
- Fasting plasma glucose concentration >120 mg/dl
- Upright diastolic blood pressure <60mmHg on three occasions 30 minutes apart (based on
scheduled research measurements).
- Treatment with a reversible MAOI within four weeks of study Phase II.
- Treatment with fluoxetine within five weeks of study Phase II.
- Treatment with any other disallowed concomitant medication 14 days before
randomization.
- Treatment with clozapine or ECT within one month of randomization.
- Lifetime history of deep brain stimulation.
- Subjects who, in the investigator's judgment, pose a current serious suicidal or
homicidal risk.
- Positive HIV test
- Contraindications to MRI (metal in body, claustrophobia, etc)
No structured psychotherapy will be permitted during the study.
Definition of treatment-resistance
All subjects are required to have previously failed to respond to two adequate
antidepressant trials (may be from the same chemical class). Adequacy of antidepressant
trials will be determined via the clinician administered modified ATHF.
We found this trial at
1
site
9000 Rockville Pike
Bethesda, Maryland 20892
Bethesda, Maryland 20892
Phone: 800-411-1222
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