Heat StressPhase 4NCT06582680
Aging, Beta Blockers, and Thermoregulatory Responses
A Phase 4 study testing Ambient Heat in people with Heat Stress and Aging, run by University of Texas Southwestern Medical Center at 1 site in United States.
Trial summary
This study will test the hypothesis that the drugs propranolol and metoprolol will result in greater increases in core body temperature during 3 hours of extreme heat exposure in older adults. Read more about this study
- Who is it for?
- Ages 65 years and olderHealthy volunteers can take part
- Conditions the study is for
- Heat Stress, Aging
- What is being tested?
- Ambient Heat
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 22 participants
- Where
- 1 siteUnited States
- Study dates
- 4 Oct 2024to 30 Sep 2026
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 65 years and older
- All sexes
- Healthy volunteers accepted
- Older adult
Who may be able to join
- Healthy and free of any significant medical problems
- Normal resting electrocardiogram
- 65+ years of age
- Controlled cholesterol of less than 200 mg/dl
- Controlled blood pressure of less than 140/90 mmHg
Who cannot join
- Known diseases or other chronic conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, uncontrolled hypertension, and uncontrolled hypercholesterolemia
- Serious abnormalities detected on routine screening
- Taking prescribed medications or over-the-counter medications that have known influences on either cardiac function or sweating
- Current smokers, as well as individuals who regularly smoked within the past 3 years
- body mass index ≥31 kg/m2
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
IEEM Texas Health Presbyterian Hospital Dallas
Dallas, Texas, 75231
Taysom Wallace, MS, 214-345-5022, taysomwallace@texashealth.org
Courtney Kirby, RN, 214-345-6502, courtneykirby@texashealth.org
About this study
This study will test the hypothesis that the drugs propranolol and metoprolol will result in greater increases in core body temperature during 3 hours of extreme heat exposure in older adults.
Read the detailed description
Older individuals are more likely to die or become ill during heat waves. During the 1995 Chicago heat wave, there was 35% increase in hospital admissions for individuals older than 65 years of age. Moreover, adults over the age of 65 have a heat-related death rate that is more than double any other age group. Therefore, with an increasing elderly population that is expected to rise by 60% (to 78 million) by 2035, the causes of this excess mortality must be understood to better protect the ageing United States population. It is notable that selective and non-selective beta blocker drugs are commonly prescribed to older individuals with cardiovascular diseases. In younger individuals exposed to a heat stress, beta blocker administration reduced whole-body sweat rate and skin blood flow responses resulting in greater increases in core body temperature. Notably, nothing is known regarding the effects of beta blockers on thermoregulatory responses during heat exposure in older individuals.
This project will evaluate core body temperature responses to selective and non-selective beta blocker drugs during simulated heat wave exposure in older individuals.
- Conditions
- Heat Stress, Aging
- Being tested
- Ambient Heat
- Medical subject headings
- Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Ambient HeatOther
Subjects will spend 3-hours in a heat chamber at 41°C and 40% humidity.
| Study group | Role | What they receive |
|---|---|---|
| Placebo, then Propranolol, then Metoprolol | Experimental | Not described Receives: Other: Ambient Heat |
| Placebo, then Metoprolol, then Propranolol | Experimental | Not described Receives: Other: Ambient Heat |
| Propranolol, then Placebo, then Metoprolol | Experimental | Not described Receives: Other: Ambient Heat |
| Propranolol, then Metoprolol, then Placebo | Experimental | Not described Receives: Other: Ambient Heat |
| Metoprolol, then Placebo, then Propranolol | Experimental | Not described Receives: Other: Ambient Heat |
| Metoprolol, then Propranolol, then Placebo | Experimental | Not described Receives: Other: Ambient Heat |
What is being measured
The primary outcome is the main question the study is designed to answer.
Internal temperature
The change in internal temperature to the 3-hour heat exposure will be measured.
Measured: Continuously throughout the 3-hour heat exposure.
Whole body sweat rate
Whole body sweat rate will be measured via changes in pre/post nude body mass.
Measured: Nude body mass will be measured before and after the 3-hour heat exposure.
Secondary outcomes (2)
Heart rate
Heart rate will be measured via electrocardiogram.
Measured: Continuously throughout the 3-hour heat exposure.
Arterial blood pressure
Systolic and diastolic arterial blood pressures will be measured via a brachial blood pressure cuff.
Measured: Continuously throughout the 3-hour heat exposure.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Sep 2024
- Study start4 Oct 2024
- Primary completion30 Sep 2026 (estimated)
- Study completion30 Sep 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heat StressStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- We will first collect participant demographics, medical history, anthropometrics (body mass, height and composition). Individuals will be exposed to 3 hours in a hot environmental condition after receiving the placebo, propranolol, or metoprolol. Prior to entering the environmental chamber, baseline data will be collected while resting in a thermoneutral environment. Drug or placebo will be administered. Participants will then enter the environmental chamber and will be seated in a semi-recumbent position on a chair with breathable fabric to minimize impediments to heat dissipation. Periodically throughout the simulated heat-wave participants will lightly exercise to simulate metabolic heat production associated with activities of daily living (\~3 metabolic equivalents; METS). Throughout the heat-wave simulation trials we comprehensively evaluate the thermoregulatory and cardiovascular responses.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 22 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Craig Crandall, University of Texas Southwestern Medical Center
- Investigators
- Craig Crandall, PhD, Principal investigator, Univ of Texas Southwestern Med Ctr
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06582680
- Sponsor's protocol ID
- STU-2024-0644
- Status last verified
- Oct 2025
- First submitted
- 30 Aug 2024
- Last updated
- 23 Oct 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 23 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Aging, Beta Blockers, and Thermoregulatory Responses
- ClinicalTrials.gov ID
- NCT06582680
- Acronym / sponsor ID
- STU-2024-0644
- Conditions
- Heat Stress, Aging
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 22 participants (estimated)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Study start
- 4 Oct 2024 (actual)
- Primary completion
- 30 Sep 2026 (estimated)
- Study completion
- 30 Sep 2026 (estimated)
- First posted
- 3 Sep 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will test the hypothesis that the drugs propranolol and metoprolol will result in greater increases in core body temperature during 3 hours of extreme heat exposure in older adults.
Detailed description
Older individuals are more likely to die or become ill during heat waves. During the 1995 Chicago heat wave, there was 35% increase in hospital admissions for individuals older than 65 years of age. Moreover, adults over the age of 65 have a heat-related death rate that is more than double any other age group. Therefore, with an increasing elderly population that is expected to rise by 60% (to 78 million) by 2035, the causes of this excess mortality must be understood to better protect the ageing United States population. It is notable that selective and non-selective beta blocker drugs are commonly prescribed to older individuals with cardiovascular diseases. In younger individuals exposed to a heat stress, beta blocker administration reduced whole-body sweat rate and skin blood flow responses resulting in greater increases in core body temperature. Notably, nothing is known regarding the effects of beta blockers on thermoregulatory responses during heat exposure in older individuals.
This project will evaluate core body temperature responses to selective and non-selective beta blocker drugs during simulated heat wave exposure in older individuals.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 6
- Model description
- We will first collect participant demographics, medical history, anthropometrics (body mass, height and composition). Individuals will be exposed to 3 hours in a hot environmental condition after receiving the placebo, propranolol, or metoprolol. Prior to entering the environmental chamber, baseline data will be collected while resting in a thermoneutral environment. Drug or placebo will be administered. Participants will then enter the environmental chamber and will be seated in a semi-recumbent position on a chair with breathable fabric to minimize impediments to heat dissipation. Periodically throughout the simulated heat-wave participants will lightly exercise to simulate metabolic heat production associated with activities of daily living (~3 metabolic equivalents; METS). Throughout the heat-wave simulation trials we comprehensively evaluate the thermoregulatory and cardiovascular responses.
| Arm | Type | Receives |
|---|---|---|
| Placebo, then Propranolol, then Metoprolol | Experimental | Other: Ambient Heat |
| Placebo, then Metoprolol, then Propranolol | Experimental | Other: Ambient Heat |
| Propranolol, then Placebo, then Metoprolol | Experimental | Other: Ambient Heat |
| Propranolol, then Metoprolol, then Placebo | Experimental | Other: Ambient Heat |
| Metoprolol, then Placebo, then Propranolol | Experimental | Other: Ambient Heat |
| Metoprolol, then Propranolol, then Placebo | Experimental | Other: Ambient Heat |
Who may qualify
- Ages
- 65 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Older adult
Key inclusion criteria (5 listed)
- Healthy and free of any significant medical problems
- Normal resting electrocardiogram
- 65+ years of age
- Controlled cholesterol of less than 200 mg/dl
- Controlled blood pressure of less than 140/90 mmHg
Key exclusion criteria (5 listed)
- Known diseases or other chronic conditions requiring regular medical therapy including cancer, diabetes, neurological diseases, uncontrolled hypertension, and uncontrolled hypercholesterolemia
- Serious abnormalities detected on routine screening
- Taking prescribed medications or over-the-counter medications that have known influences on either cardiac function or sweating
- Current smokers, as well as individuals who regularly smoked within the past 3 years
- body mass index ≥31 kg/m2
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Ambient HeatSubjects will spend 3-hours in a heat chamber at 41°C and 40% humidity. | Other | Metoprolol, then Placebo, then Propranolol, Metoprolol, then Propranolol, then Placebo, Placebo, then Metoprolol, then Propranolol, Placebo, then Propranolol, then Metoprolol, Propranolol, then Metoprolol, then Placebo, Propranolol, then Placebo, then Metoprolol |
Primary outcome
Internal temperature
Time frame: Continuously throughout the 3-hour heat exposure.
The change in internal temperature to the 3-hour heat exposure will be measured.
Whole body sweat rate
Time frame: Nude body mass will be measured before and after the 3-hour heat exposure.
Whole body sweat rate will be measured via changes in pre/post nude body mass.
2 secondary outcomes
Heart rate
Time frame: Continuously throughout the 3-hour heat exposure.
Arterial blood pressure
Time frame: Continuously throughout the 3-hour heat exposure.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Oct 2025.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Craig Crandall, PhD principal investigator
Univ of Texas Southwestern Med Ctr
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Ambient Heat in people with Heat Stress and Aging, run by University of Texas Southwestern Medical Center at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 23 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Erin Harper, MS (214-345-4737, erinharper@texashealth.org), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Internal temperature (time frame: Continuously throughout the 3-hour heat exposure.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Oct 2025.