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Sponsors and Collaborators: |
Centre for Addiction and Mental Health Stanley Medical Research Institute |
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Information provided by: | Centre for Addiction and Mental Health |
ClinicalTrials.gov Identifier: | NCT00362804 |
Purpose of Study:
A) To improve outcome in large population of antipsychotic patients with schizophrenia or schizoaffective who are only partial responders B) To increase understanding of pharmacology and mechanisms of action underlying antipsychotic effect
Hypothesis/Objectives of the Study:
Tetrabenazine, through its pre-synaptic action, should augment the post-synaptic effects of an antipsychotic.
Background and Rationale for the study:
Preliminary evidence that other amine-depleting agents e.g., reserpine, can induce such an effect
Condition | Intervention |
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Schizophrenia Schizoaffective Disorder |
Drug: Tetrabenazine |
Study Type: | Interventional |
Study Design: | Treatment, Randomized, Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Placebo Control, Parallel Assignment, Efficacy Study |
Official Title: | Augmentation of Antipsychotic Partial Responders With Tetrabenazine |
Estimated Enrollment: | 60 |
Study Start Date: | February 2002 |
Estimated Study Completion Date: | May 2008 |
Primary Completion Date: | November 2006 (Final data collection date for primary outcome measure) |
Since the 1950's, antipsychotics have been used as the mainstay treatment to control symptoms of schizophrenia.
However, soon after their introduction it became apparent that a substantial number of individuals show a less than optimal response to these drugs - as many as 30% of schizophrenics using conventional antipsychotics derive little benefit. Furthermore, 'atypical' generation antipsychotics such as clozapine which proves to be the most beneficial for partial responders and represents the cornerstone of treatment-resistant schizophrenia, offers a response rate as low as 30% in those showing an inadequate response. Moreover, many individuals decline clozapine as an option, or cannot tolerate it.
For these reasons, augmentation strategies play an important role in the treatment of antipsychotic partial responders. We have systematically reviewed the different augmentation options, and reached the conclusion that most such strategies are theoretically speculative and empirically unsupported.
At the same time though, we recognize that augmentation strategies are common practice in the clinical setting.
With so many individuals showing only a partial response to antipsychotic treatment (typical or atypical), it has become a practical reality in efforts to offer further improvement. Often, this come in the form of adding one or even more antipsychotics, although the evidence for such an approach is less than compelling and neuroimaging from our centre has cautioned against this approach.
With a variety of other potential augmentation strategies available, we have chosen to focus on tetrabenazine (TBZ), which is currently licensed here in Canada for the management of hyperkinetic movement disorders.
The choice of TBZ as an augmentation strategy arises from several lines of investigation:
We are proposing to carry out a controlled double-blind trial, using TBZ off-label in patients with schizophrenia or schizoaffective disorder only partially responsive to antipsychotics. We feel that the choice of this approach is empirically sound and, in fact, offers advantages to the more common approach of adding several antipsychotics. Our decision to maintain out focus on the dopaminergic system arises from the growing body of evidence that dopamine blockade, particularly at the level of the D2 receptor, is central to antipsychotic activity, in combination with the lack of current evidence supporting the distinct advantages of incorporating other systems.
Given the limited success with augmentation strategies in schizophrenic patients to date, any evidence of efficacy and safety with this combination will add considerably to options that might be considered in the clinical setting. This same information could also prove very useful in shaping investigations related to the pharmacology of schizophrenia and development of future compounds.
Ages Eligible for Study: | 18 Years to 65 Years |
Genders Eligible for Study: | Both |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
Exclusion Criteria:
Canada, Ontario | |
Centre for Addiction and Mental Health | |
Toronto, Ontario, Canada, M5T 1R8 |
Principal Investigator: | Gary Remington, MD | Centre for Addiction and Mental Health |
Responsible Party: | CAMH ( Dr. Gary Remington ) |
Study ID Numbers: | 240/2001 |
Study First Received: | August 9, 2006 |
Last Updated: | March 4, 2008 |
ClinicalTrials.gov Identifier: | NCT00362804 History of Changes |
Health Authority: | Canada: Health Canada |
tetrabenazine partial response psychosis |
schizophrenia schizoaffective disorder partial response to antipsychotics |
Schizophrenia Neurotransmitter Agents Tranquilizing Agents Adrenergic Agents Mental Disorders Psychotropic Drugs |
Central Nervous System Depressants Psychotic Disorders Antipsychotic Agents Schizophrenia and Disorders with Psychotic Features Tetrabenazine |
Neurotransmitter Agents Neurotransmitter Uptake Inhibitors Tranquilizing Agents Adrenergic Agents Molecular Mechanisms of Pharmacological Action Adrenergic Uptake Inhibitors Physiological Effects of Drugs Psychotropic Drugs Central Nervous System Depressants |
Antipsychotic Agents Pharmacologic Actions Schizophrenia Mental Disorders Therapeutic Uses Psychotic Disorders Central Nervous System Agents Schizophrenia and Disorders with Psychotic Features Tetrabenazine |