Do Common Over-the-counter Antihistamine Medications Modify Thermoregulatory Responses During Passive Heat Stress?
试验速览
- 阶段
- 4 期
- 状态
- 招募中
- 入组人数
- 16
- 试验地点
- 1
- 主要终点
- Local Sweat Rate
研究概览
简要总结
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.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Other
- 盲法
- Double (Participant, Investigator)
盲法说明
Participants will be informed of the study interventions prior to experimental trials to ensure participants are able to provide informed consent. However, participants will blinded to the order of the arms (i.e., participants will not be informed which antihistamine/placebo pill they ingest for any trial). Data will remain blinded to researchers until after a third-party statistical analysis.
入排标准
- 年龄范围
- 19 Years 至 39 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Male or Female between ages 19 and 39 years
- •Fully vaccinated against COVID-19
- •Able to provide informed consent
- •Body-mass index under 30
排除标准
- •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
研究组 & 干预措施
50 mg Diphenhydramine
干预措施: 50 mg Diphenhydramine (Drug)
10 mg Loratadine
干预措施: 10 mg Loratadine (Drug)
5 mg Desloratadine
干预措施: 5 mg Desloratadine (Drug)
Placebo (Sugar pill)
干预措施: Placebo (Sugar Pill) (Other)
结局指标
主要结局
Local Sweat Rate
时间窗: 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
Measured using ventilated sweat capsules affixed to forearm and chest
Heart Rate
时间窗: 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
Measured using electrocardiogram
Whole-Body Sweat Losses
时间窗: For each study arm (all completed within 4 months), measurements taken immediately before heating protocol & immediately following the heating protocol
Difference in participants' pre/post body mass
Skin Blood Flow
时间窗: 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
Measured using laser-doppler skin blood blow sensor affixed to forearm
Mean Arterial Pressure
时间窗: 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
Measured using brachial blood pressure cuff
次要结局
- Thermal Comfort(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)
- Mental Acuity(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)
- Sleepiness/Fatigue level(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)
- Thermal Sensation(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)
研究者
Nicholas Ravanelli
Principal Investigator, Assistant Professor
Lakehead University