Clinical trial NCT06582680: Aging, Beta Blockers, and Thermoregulatory Responses
Official title: Aging, Beta Blockers, and Thermoregulatory Responses
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: PHASE4
Conditions: Heat Stress
Aging
Lead sponsor: University of Texas Southwestern Medical Center
Sponsor class: OTHER
First posted: 2024-09-03
Enrollment: 22
Sex: ALL
Minimum age (years): 65
Standard ages: OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention 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.
Primary purpose: BASIC_SCIENCE

Brief 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.

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.

Eligibility criteria: Inclusion Criteria:

* 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

Exclusion Criteria:

* 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

Primary outcomes:
measure: Internal temperature
timeFrame: Continuously throughout the 3-hour heat exposure.
measure: Whole body sweat rate
timeFrame: Nude body mass will be measured before and after the 3-hour heat exposure.
Secondary outcomes:
measure: Heart rate
timeFrame: Continuously throughout the 3-hour heat exposure.
measure: Arterial blood pressure
timeFrame: Continuously throughout the 3-hour heat exposure.
Other outcomes:
Locations:
city: Dallas
country: United States
facility: IEEM Texas Health Presbyterian Hospital Dallas
state: Texas
Study officials:
affiliation: Univ of Texas Southwestern Med Ctr
name: Craig Crandall, PhD
role: PRINCIPAL_INVESTIGATOR
References: