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CompletedNCT01999530Updated May 30, 2019Results posted

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

A Phase 1 interventional study of Prazosin Hydrochloride in Healthy, sponsored by Centre for Addiction and Mental Health. Completed at 1 site in Canada. Open to participants aged 19 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2019-05-30.

Sponsored by Centre for Addiction and Mental Health · Phase 1, Interventional, and Basic science

Phase
Phase 1
Study type
Interventional
Enrollment
20
Allocation
Not applicable
Ages
19 Years to 45 Years
Sex
All
01

Study summary

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.

Read the 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.

02

Conditions studied

  • Healthy

Keywords

  • prazosin
  • dopamine
  • healthy
  • Positron Emission Tomography
  • PHNO
  • scan
  • effect
03

In context

Lead sponsor

Centre for Addiction and Mental Health is the lead sponsor of 327 studies on the registry; 51 are open to participants now.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
19 Years to 45 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Inclusion criteria

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

Exclusion criteria

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
05

Study design

Phase
Phase 1
Primary purpose
Basic science
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrollment
20 participants (actual)

Study arms

  • Experimental
    Prazosin Hydrochloride

    Gradual upward titration to 15mg/day (or highest dose tolerated) for approximately three weeks.

    Drug: Prazosin Hydrochloride

Interventions

  • DrugPrazosin Hydrochloride

    Gradual upward titration to 15mg/day for approximately three weeks.

    Also known as: Teva-Prazosin, Prazosin, Minipress

06

What researchers measure

Primary outcomes

  1. Changes in [11C]-(+)-PHNO Binding (Measured as Binding Potential) in Dorsal Caudate (DC)

    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

    Time frame: 3 weeks after taking prazosin

07

Results

Posted May 17, 2019

Participant flow

Participant flow — Overall Study
MilestonePrazosin Hydrochloride
Started20
Completed7
Not completed13

Outcome measures

PrimaryChanges in [11C]-(+)-PHNO Binding (Measured as Binding Potential) in Dorsal Caudate (DC)

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

Time frame:
3 weeks after taking prazosin
Reported as:
Mean · binding potential
Changes in [11C]-(+)-PHNO Binding (Measured as Binding Potential) in Dorsal Caudate (DC)
binding potentialPrazosin Hydrochloride
Changes in [11C]-(+)-PHNO Binding (Measured as Binding Potential) in Dorsal Caudate (DC)2.1 (1.4 to 2.8)

Adverse events

Non-serious events are listed at a 5% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Prazosin Hydrochloride—0/20 (0%)6/20 (30%)
Most frequent other events
Most frequent other events
EventPrazosin Hydrochloride
NauseaGastrointestinal disorders6/20

Baseline characteristics

Age, Categorical
Age, Categorical(Participants)Prazosin Hydrochloride
<=18 years0
Between 18 and 65 years7
>=65 years0
Sex: Female, Male
Sex: Female, Male(Participants)Prazosin Hydrochloride
Female0
Male7
Race/Ethnicity, Customized
Race/Ethnicity, Customized(participants)Prazosin Hydrochloride
Asian1
Caucasian3
Hispanic2
Mixed1
Region of Enrollment
Region of Enrollment(participants)Prazosin Hydrochloride
Canada7
08

Study locations

1 site
  • Centre for Addiction and Mental Health
    Toronto, Ontario M5T 1R8, Canada
09

References and documents

Individual participant data

Plan to share: No

10

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on May 30, 2019, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT01999530
Lead sponsor
Centre for Addiction and Mental Health
Collaborators
Ontario Lung Association, Pfizer
Responsible party
Bernard Le Foll (Principal Investigator, Centre for Addiction and Mental Health) — Principal investigator
First posted
Dec 3, 2013
Start date
Nov 2013
Primary completion
Aug 2016
Completion
Aug 2016
Results posted
May 17, 2019
Last update
May 30, 2019

Study contacts

Bernard Le Foll, MD, PhD
principal investigator · Centre for Addiction and Mental Health

Oversight

Data monitoring committee
No
View the source record on ClinicalTrials.gov ↗

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