The Effects of Prazosin on Dopamine in Healthy Humans: A PET Pilot Study

May 17, 2019 updated by: Bernard Le Foll, Centre for Addiction and Mental Health

Exploring the Effects of Prazosin on Basal Dopamine in Healthy Humans: A [11C]-(+)-PHNO PET Pilot Study

The purpose of this study is to find out whether short term treatment with a antihypertensive medication prazosin, can influence the levels of a dopamine in the brain. We will examine the levels of dopamine in the the brain using Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI). We hypothesize that there will be no significant changes in dopamine levels in healthy individuals taking prazosin.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

The purpose of this study is to find out whether short term treatment with a antihypertensive medication prazosin, can influence the levels of dopamine in the brain. We will examine the levels of dopamine in the the brain using Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI). The study will involve three PET scans and one MRI. One PET scan will be performed before the participants take prazosin for approximately three weeks, and the last two PET scans will be performed after the prazosin medication phase. We hypothesize that there will be no significant changes in dopamine levels in healthy individuals taking prazosin.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Canada
    • Ontario
      • Toronto, Ontario, Canada, M5T 1R8
        • Centre for Addiction and Mental Health

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

15 years to 41 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Healthy males and females of any ethnic origin between 19 and 45 years old

Exclusion Criteria:

  • Use of any illicit drugs in past 3 months prior to randomization and/or have a current or past diagnosis of drug abuse/dependence (including alcohol)
  • Current or past DSM-IV diagnosis of any Axis I psychiatric disorder
  • Major psychiatric illness and/or substance dependence in first order relatives
  • Current active or past suicidal ideation
  • Baseline systolic blood pressure outside the normal range
  • Current use of medications that could interact with prazosin (e.g. beta blockers, phosphodiesterasetype 5 inhibitors, indomethacin, verapamil, modafinil, clonidine)
  • Current use or use during the previous month of medication that may affect the CNS at the time of scanning (e.g. neuroleptics, bupropion)
  • Any significant abnormalities in baseline blood results (e.g. CBC, renal and hepatic indicators) or ECG readings that would preclude the use of prazosin
  • Pregnancy, trying to become pregnant or breastfeeding
  • Presence of metal objects in the body (e.g. some artificial joints, bone pins, surgical clips, skull plate, certain part of dental braces) or implanted electronic devices (e.g. cardiac pacemaker, neurostimulator), that preclude safe MR scanning
  • Claustrophobia
  • Participation in any nuclear medicine procedures that, including the dose received during participation in this study, will bring the total radiation dose over the currently approved guideline of 20mSv in a 12-month period
  • Cardiovascular or cerebrovascular diseases
  • History of or current neurological illnesses including seizure disorders, migraine, multiple sclerosis, movement disorders, head trauma, CVA or CNS tumor
  • Abnormal body mass (defined as not within 20% of normal BMI
  • Learning disability, amnesia or other conditions that impede memory and attention

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Prazosin Hydrochloride
Gradual upward titration to 15mg/day (or highest dose tolerated) for approximately three weeks.
Drug: Prazosin Hydrochloride
Gradual upward titration to 15mg/day for approximately three weeks.
Other Names:
  • Minipress
  • Prazosin
  • Teva-Prazosin

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Changes in [11C]-(+)-PHNO Binding (Measured as Binding Potential) in Dorsal Caudate (DC)
Time Frame: 3 weeks after taking prazosin
Binding potential (an estimate of the ratio of Bmax/kd) was measured by positron emission tomography to determine if taking prazosin alters the amount of tracer bound to receptors. A negative change in binding potential means a decrease in binding potential and a positive change in binding potential represents an increase. Bmax is the total density of receptors. kd is the affinity of a drug for the target
3 weeks after taking prazosin

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Centre for Addiction and Mental Health

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Pfizer
Ontario Lung Association

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 1, 2013

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 1, 2016

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2016

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 26, 2013

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 26, 2013

First Posted (Estimate)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
December 3, 2013

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 30, 2019

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 17, 2019

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2019

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 224/2012

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

No

Study Data/Documents

  1. Publication

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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