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CompletedNCT04423627SELECTUpdated Aug 8, 2025

Sympathetic Regulation of Large Artery Stiffness in Humans With ISH

An Early Phase 1 interventional study of Clonidine and Hydrochlorothiazide in Hypertension, Systolic and Stiffness, Aortic, sponsored by University of Iowa. Completed at 2 sites in United States. Open to participants aged 60 Years to 85 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-08-08.

Sponsored by University of Iowa · Early Phase 1, Interventional, and Treatment

From the registry’s dates

  • Primary completion was Jul 2025, 1 year 2 months ago, and no results have been posted to the registry.
Phase
Early Phase 1
Study type
Interventional
Enrollment
100
Allocation
Randomized
Ages
60 Years to 85 Years
Sex
All
01

Study summary

Stiffening of your blood vessels, particularly the large vessels from your heart (called the aorta and carotids) you age contributes to the development of cardiovascular disease (CVD) such as heart attack and stroke. Nerve activity from your brain to your body also increases with advancing age but it is unknown if this nerve activity contributes directly to the stiffening on your blood vessels in older adults in addition to high blood pressure. Therefore, successful completion of the proposed aims will have a significant clinical impact by identifying if nerve activity from your brain could be a novel target for therapies that would lower stiffness of the aorta and carotid arteries in older adults.

02

Conditions studied

  • Hypertension, Systolic
  • Stiffness, Aortic
03

In context

Isolated Systolic Hypertension

39 studies on the registry are indexed under Isolated Systolic Hypertension; 8 are open to participants now.

This study's enrollment of 100 is below the median of 144 across 33 interventional studies indexed under Isolated Systolic Hypertension.

Browse Isolated Systolic Hypertension studies →

Lead sponsor

University of Iowa is the lead sponsor of 276 studies on the registry; 35 are open to participants now.

Of its 44 completed or terminated interventional studies of FDA-regulated products, 39 (89%) have results posted.

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

04

Who can participate

Ages eligible
60 Years to 85 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Inclusion criteria

  • age 60-85
  • non-smoking
  • clinically healthy
  • untreated or treated stage 1 isolated systolic hypertension (ISH) (systolic BP 130-139 mmHg; diastolic BP \<90 mmHg) or stage 2 ISH (systolic BP 140-159 mmHg; diastolic BP \<90 mmHg) per 2017 AHA/ACC hypertension guidelines
  • if subject is on antihypertensive medications, they will stop taking medication for a one-week washout period after Visit 1 before they return for Visit 2. They will come in at day 3 and day 7 of the one-week washout for a BP reading, to confirm that systolic BP is \<160 mmHg.

Exclusion criteria

Exclusion Criteria:

  • no history of cardiovascular disease (e.g., myocardial infarction, bypass surgery, angioplasty/stent, heart failure, cardiomyopathy, pacemaker/defibrillator, peripheral artery disease), pulmonary disease, liver disease, Type I or II diabetes, cancer (treated by chemotherapy and/or radiation), psychiatric illness, on aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs).
  • aspirin, NSAIDs, vitamins, herbal supplements, omega-3-fatty acids will have to discontinue for at least 1 week before participation and remain discontinued during the study.
  • blood thinners, serotonin reuptake inhibitors (SSRIs), or PDE5 inhibitors will also be excluded.
  • Women must be postmenopausal for at least 6 months (surgical or natural) and not currently on hormone replacement therapy.
  • Subjects not on antihypertensive will not be eligible if their resting clinic systolic BP is \<130 mmHg or >160 mmHg and diastolic BP >90 mmHg.
05

Study design

Phase
Early Phase 1
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Triple (Participant, Care provider, Investigator)
Enrollment
100 participants (actual)

Study arms

  • Experimental
    Clonidine

    0.2 mg/day oral

    Drug: Clonidine

  • Active comparator
    Hydrochlorothiazide

    37.5 mg/day oral

    Drug: Hydrochlorothiazide

  • Placebo comparator
    Placebo

    Placebo

    Drug: Placebo

Interventions

  • DrugClonidine

    Clonidine 0.2 mg/day oral tablet

  • DrugHydrochlorothiazide

    Hydrochlorothiazide 37.5 mg/day oral tablet

  • DrugPlacebo

    Placebo

06

What researchers measure

Primary outcomes

  1. Change in carotid-femoral pulse wave velocity

    Aortic stiffness

    Time frame: Baseline and after 4 weeks

Secondary outcomes

  1. Change in carotid distensibility index

    Change in carotid distensibility

    Time frame: Baseline and after 4 weeks

  2. Change in carotid flow pulsatility index

    Change in carotid flow pulsatility

    Time frame: Baseline and after 4 weeks

  3. Change in carotid intimal medial thickness (IMT)

    Change in carotid wall thickness

    Time frame: Baseline and after 4 weeks

07

Study locations

2 sites
  • Amy Stroud
    Iowa City, Iowa 52240, United States
  • University of Iowa
    Iowa City, Iowa 52242, United States
08

References and documents

Individual participant data

Plan to share: No

No publications or documents are linked to this record.

09

Updates

Tracking since Sep 25, 2026
No changes since tracking began. The registry record was last updated on Aug 8, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
10

Registry details

Key details

Study ID
NCT04423627
Lead sponsor
University of Iowa
Responsible party
Gary L. Pierce, PhD (Associate Professor, University of Iowa) — Principal investigator
First posted
Jun 9, 2020
Start date
Jun 1, 2021
Primary completion
Jul 31, 2025
Completion
Jul 31, 2025
Last update
Aug 8, 2025

Study contacts

Gary Pierce, PhD
principal investigator · University of Iowa

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.

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