Aging, Beta Blockers, and Thermoregulatory Responses

Phase 4

Recruiting

• Conditions: Heat Stress; Aging
• Interventions: Drug: Propranolol; Drug: Metoprolol; Other: Placebo

• Registration Number: NCT06582680
• Lead Sponsor: University of Texas Southwestern Medical Center

Brief Summary

We 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 Timeline

• Study First Submitted: 2024-08-30
• Study First Submitted QC: 2024-08-30
• Study First Posted: 2024-09-03
• Status Verified: 2024-10
• Study Start: 2024-10-04
• Last Update Submitted: 2024-10-18
• Last Update Posted: 2024-10-21
• Primary Completion: 2026-09-30
• Study Completion: 2026-09-30

Recruitment & Eligibility

• Status: RECRUITING
• Sex: All
• Target Recruitment: 22

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

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Propranolol	Propranolol	Propranolol will be administered before heat exposure.
Metoprolol	Metoprolol	Metoprolol will be administered before heat exposure.
Placebo	Placebo	A placebo will be administered before heat exposure.

Primary Outcome Measures

Name	Time	Method
Internal temperature	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	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.

Secondary Outcome Measures

Name	Time	Method
Heart rate	Continuously throughout the 3-hour heat exposure.	Heart rate will be measured via electrocardiogram.
Arterial blood pressure	Continuously throughout the 3-hour heat exposure.	Systolic and diastolic arterial blood pressures will be measured via a brachial blood pressure cuff.

Trial Locations

Locations (1)

IEEM Texas Health Presbyterian Hospital Dallas; 🇺🇸 Dallas, Texas, United States