Over-the-Counter Antihistamines & Heat Stress

Allergic Rhinitis Clinical Trial

Official title:

Do Common Over-the-counter Antihistamine Medications Modify Thermoregulatory Responses During Passive Heat Stress?

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT06217367
• Other study ID #: 100241
• Secondary ID: 273752
• Status: Recruiting
• Phase: Phase 4
• Start date: December 5, 2023
• Est. completion date: June 2024

Study information

• Verified date: January 2024
• Source: Lakehead University
• Contact: Nicholas Ravanelli, PhD
• Phone: 6132630361
• Email: nravanel[@]lakeheadu.ca
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

Allergic rhinitis (AR) currently affects ~25% of Canadians, and due to factors of climate change, this number is expected to increase over the coming decade. AR symptoms can significantly impact individuals' quality of life by compromising sleep, productivity, and social interactions. To alleviate AR symptoms, North Americans tend to rely on H1 antihistamine medications available over-the-counter (OTC) at most pharmacies. However, public health authorities currently suggest restraining all antihistamines during heat waves due to beliefs that M3 muscarinic receptor and H1 receptor antagonism, independent pharmacological mechanisms of H1 antihistamines, might suppress thermoregulatory responses to heat stress and increase individuals' susceptibility to heat-related illness/injury. To date, studies using supramaximal doses of antihistamines have demonstrated reductions in sweating, however these doses and administration routes are not the typical use case. Additional studies utilizing fexofenadine, a second-generation H1 antihistamine, have linked H1 receptor antagonism to reductions in skin blood flow, potentially impacting thermoregulation by reducing peripheral blood redistribution. Empirical evidence supporting OTC H1 antihistamines impacting thermoregulatory control at recommended doses is scarce. Thus, this study aims to systematically assess whether three common OTC H1 antihistamines, taken as prescribed, alter thermoregulatory responses during thermal stress.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 16
• Est. completion date: June 2024
• Est. primary completion date: June 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 19 Years to 39 Years

Eligibility

Inclusion Criteria:

• Male or Female between ages 19 and 39 years
• Fully vaccinated against COVID-19
• Able to provide informed consent
• Body-mass index under 30

Exclusion Criteria:

• Body-mass index over 30
• Currently taking sedative or autonomic nervous system depressant medication
• Hypersensitivity to diphenhydramine, loratadine, or desloratadine
• History of cardiovascular disease, cancer, type 1 or 2 diabetes, chronic obstructive pulmonary disorder, or cystic fibrosis
• Have smoked tobacco products less than 12 months prior to participation
• Pregnant/Breastfeeding

Related Conditions & MeSH terms

• Allergic Rhinitis
• Heat Illness
• Heat Stress Disorders
• Rhinitis
• Rhinitis, Allergic

Intervention

Drug:
• 50 mg Diphenhydramine
Participants ingest 50mg of diphenhydramine orally ~2 hours prior to a passive heating protocol. Participants then don a water-perfusion heat suited and lay supine on assessment table while 49? is circulated throughout the garment. Heating persists until participants reach a 1.5? increase in core temperature from baseline.
• 10 mg Loratadine
Participants ingest 10 mg of loratadine orally ~2 hours prior to a passive heating protocol. Participants then don a water-perfusion heat suited and lay supine on assessment table while 49? is circulated throughout the garment. Heating persists until participants reach a 1.5? increase in core temperature from baseline.
• 5 mg Desloratadine
Participants ingest 5 mg of desloratadine orally ~2 hours prior to a passive heating protocol. Participants then don a water-perfusion heat suited and lay supine on assessment table while 49? is circulated throughout the garment. Heating persists until participants reach a 1.5? increase in core temperature from baseline.

Other:
• Placebo (Sugar Pill)
Participants ingest placebo pill orally ~2 hours prior to a passive heating protocol. Participants then don a water-perfusion heat suited and lay supine on assessment table while 49? is circulated throughout the garment. Heating persists until participants reach a 1.5? increase in core temperature from baseline.

Locations

Country	Name	City	State
Canada	Lakehead University C.J Sanders Fieldhouse	Thunder Bay	Ontario

Sponsors (1)

Lead Sponsor	Collaborator
Lakehead University

Country where clinical trial is conducted

Canada, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Whole-Body Sweat Losses	Difference in participants' pre/post body mass	For each study arm (all completed within 4 months), measurements taken immediately before heating protocol & immediately following the heating protocol
Primary	Skin Blood Flow	Measured using laser-doppler skin blood blow sensor affixed to forearm	For each study arm (all completed within 4 months), measured before heating, and at every 0.25C increase in core temperature (+0.25C, +0.50C, +0.75C, +1.0C, +1.25C, and +1.5C), or every ~15 minutes of (up to ~90 minutes) and immediately after heating
Primary	Heart Rate	Measured using electrocardiogram	For each study arm (all completed within 4 months), measured before heating, and at every 0.25C increase in core temperature (+0.25C, +0.50C, +0.75C, +1.0C, +1.25C, and +1.5C), or every ~15 minutes of (up to ~90 minutes) and immediately after heating
Primary	Mean Arterial Pressure	Measured using brachial blood pressure cuff	For each study arm (all completed within 4 months), measurements taken at baseline before heating, and every 10 minutes throughout heating protocol (up to ~ 90 minutes), and immediately after heating
Primary	Local Sweat Rate	Measured using ventilated sweat capsules affixed to forearm and chest	For each study arm (all completed within 4 months), measured before heating, and at every 0.25C increase in core temperature (+0.25C, +0.50C, +0.75C, +1.0C, +1.25C, and +1.5C), or every ~15 minutes of (up to ~90 minutes) and immediately after heating
Secondary	Thermal Sensation	Self-assessments of thermal sensation using a 7-point analog scale where -3 is "Cold" and +3 is "Hot".	For each study arm (all completed within 4 months), measured before heating, and at every 0.25C increase in core temperature (+0.25C, +0.50C, +0.75C, +1.0C, +1.25C, and +1.5C), or every ~15 minutes of (up to ~90 minutes) and immediately after heating
Secondary	Thermal Comfort	Self-assessments of thermal comfort using four-point analog scale where 1 is "Not uncomfortable" and 4 is "Very uncomfortable"	For each study arm (all completed within 4 months), measured before heating, and at every 0.25C increase in core temperature (+0.25C, +0.50C, +0.75C, +1.0C, +1.25C, and +1.5C), or every ~15 minutes of (up to ~90 minutes) and immediately after heating
Secondary	Mental Acuity	Indexed with digital Stroop test	For each study arm (all completed within 4 months), measurements taken 2 hours before heating (pre-pill ingestion), 5-minutes before initiating heating, and within 5-minutes after the heating protocol
Secondary	Sleepiness/Fatigue level	Measured using Stanford Sleepiness Scale (min: 1, max: 7 (more fatigued))	For each study arm (all completed within 4 months), measurements taken 2 hours before heating (pre-pill ingestion), 5-minutes before initiating heating, and within 5-minutes after the heating protocol