Aging, Beta Blockers, and Thermoregulatory Responses

The University of Texas System (UT)

Status and phase: Enrolling; Phase 4

Conditions: Aging; Heat Stress

Treatments: Other: Ambient Heat

Study type: Interventional

Funder types: Other

Identifiers

NCT06582680

STU-2024-0644

Details and patient eligibility

About

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.

Full 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.

Enrollment: 22 estimated patients

Sex: All

Ages: 65+ years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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22 participants in 6 patient groups

Placebo, then Propranolol, then Metoprolol

Experimental group

Treatment:

Other: Ambient Heat

Placebo, then Metoprolol, then Propranolol

Experimental group

Treatment:

Other: Ambient Heat

Propranolol, then Placebo, then Metoprolol

Experimental group

Treatment:

Other: Ambient Heat

Propranolol, then Metoprolol, then Placebo

Experimental group

Treatment:

Other: Ambient Heat

Metoprolol, then Placebo, then Propranolol

Experimental group

Treatment:

Other: Ambient Heat

Metoprolol, then Propranolol, then Placebo

Experimental group

Treatment:

Other: Ambient Heat