Phase 2
Completed N=17
MIrabegron and Physiological Function in Cold Environments
Resting Energy Expenditure · Thermogenesis · Brown Adipose Tissue
Source: ClinicalTrials.gov NCT05990387 ↗
Enrolled (actual)
17
Serious AEs
0.0%
Results posted
Jul 2025
Primary outcomePrimary: Cold Temperature Deflection Point — 22.8; 22.97 degrees Celsius
Summary
Many Navy diving operations are performed in cold water. Despite technical advances to improve thermal protection for cold water diving, these applications are cumbersome and do not provide complete thermal protection as thermal discomfort is subjectively reported by many Navy divers. Brown adipose tissue is highly thermogenic in humans. Therefore, activation of brown adipose tissue might improve cold water tolerance and lower thermal discomfort during cold water diving operations. Mirabegron is a beta-3-adrenergic receptor agonist that is used to treat overactive bladder. Beta-3-adrenergic receptors are located on the urinary bladder, gallbladder and brown adipose tissue. Recent evidence has demonstrated that acute mirabegron administration increases thermogenesis for ~3 hours in humans. However, it is currently not known which dose of mirabegron can increase thermogenesis for longer durations. It is also not known if mirabegron administration can improve cold water tolerance and thermal discomfort during cold water immersion. Finally, it is not known if mirabegron can increase thermogenesis during sympathetic stimulation. This project will fill these knowledge gaps by determining if acute mirabegron administration will delay the fall in core temperature and the onset of shivering during a progressive cold-water immersion challenge. This study is part of a collection of studies that will show if mirabegron is a potential ergogenic aid that can be used to improve cold water tolerance in Navy divers which will ultimately improve the likelihood of successful missions.
Outcome Measures
| Outcome | Result | p-value |
|---|---|---|
| PRIMARY Cold Temperature Deflection Point |
22.8; 22.97 | — |
| SECONDARY Thermogenesis - Oxygen Consumption |
7.2; 7.6 | — |
| SECONDARY Shivering Inflection Point - Surface Mechanomyography |
24.1; 22.7 | — |
| SECONDARY Shivering Inflection Point - Bedside Shivering Scale |
22.1; 19.8 | — |
Eligibility Criteria
Inclusion Criteria
- Men and women
- 18-40 years old
- Participate in 150 minutes or more of at least moderate intensity exercise per week during the previous 2 years
Exclusion Criteria
- diagnosed autonomic disease
- diagnosed cardiovascular disease
- diagnosed metabolic disease
- diagnosed neurologic disease
- diagnosed endocrine disease
- diagnosed respiratory disease
- diagnosed liver dysfunction
- diagnosed kidney dysfunction
- Women who are pregnant or breastfeeding
- Individuals currently taking a medication (with the exception of birth control, including hormonal contraception) that cannot be safely discontinued for 5 biological half-lifes prior to each study visit based on consultation with the study physician.
- Current tobacco or electronic cigarette use or consistent use within the last 1 year
Data sourced from ClinicalTrials.gov (NCT05990387). Outcome figures and adverse-event rates are extracted automatically from the registry's posted results and are provided for clinician reference, not as a substitute for the primary publication. Informational only — not medical advice.