Testing Diphenhydramine hydrochloride with Exercise Bout against a placebo for histamine
Official title: Histamines and Central Hemodynamics
The Role of Histamines on Central Hemodynamics
- 2 groups
- One site, in Kelowna
- Recruiting
Interventions
- Medication
Diphenhydramine hydrochloride
H1 receptor antagonist: 50mg Diphenhydramine Hydrochloride
- Other intervention
Placebo
Placebo
- Other intervention
Exercise Bout
Participants will complete a total of three 5-minute high intensity exercise intervals, interspersed with 5-minute lower intensity exercise bouts (4 total), for a total of 35 minutes.
Canadian Sites (1)
1 of 1 recruiting
- Recruiting
University of British Columbia
Kelowna, British Columbia
Eligibility Criteria
See who this study is looking for15 criteria
The trial’s own eligibility text, word for word from the registry. Only the trial site can say who takes part.
Inclusion
- +Age: 19 - 39.
- +Willing to visit the lab on 3 separate occasions.
Exclusion
- −Previously diagnosed heart condition,
- −Previously diagnosed lung condition (including asthma),
- −Previously diagnosed metabolic condition,
- −Resting blood pressure \>140/90 mmHg,
- −Unable to obtain appropriate quality ultrasound images of the heart.,
- −Individuals without tricuspid regurgitation at rest to allow assessment of the primary outcomePrimary endpointThe single main question the study is designed to answer.Read more →,
- −Chronically take antihistamines (i.e. daily),
- −History of adverse reactions to antihistamines,
- −Never taken antihistamines previously,
- −Pregnant or trying to become pregnant,
- −Breastfeeding,
- −Currently taking any medications (including oral contraceptives).
- −Currently smokers (cigarettes, electronic cigarettes, cannabis) or who have smoked within the last 3 months,
In plain language
Assembled directly from this trial’s registry record. Every sentence traces to a field below — nothing here is generated or interpreted.
What this study is
This study is investigating how something functions in the body, rather than testing a treatment directly.
This study is not organised into the usual phase numbers — that is common for device, behavioural, and diagnostic research.
From the trial registry
Built from these fields:
- designModule.designInfo.primaryPurpose
- designModule.phases
Who receives what
There are 2 groups in this study.
Group A receives Exercise Bout, together with one or more of: Diphenhydramine hydrochloride.
Registry label: A: Blockade + Exercise Bout
Group B, the placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group, receives Placebo and Exercise Bout.
Registry label: B: Placebo + Exercise Bout
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].label
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
How the study is run
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
You, the study team, and the people analysing the results would all be kept unaware of which group you are in until the study ends.
From the trial registry
Built from these fields:
- designModule.designInfo.allocation
- designModule.designInfo.maskingInfo.masking
Is there a placebo?
One group receives a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → — a dummy treatment with no active medicine in it.
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
Who the study is looking for
The study lists an age range of 19 years to 39 years.
The study is open to people of any sex.
The study accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
These are the criteria the study lists. Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part.
From the trial registry
Built from these fields:
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How big and how long
The study aims to enrol about 20 people.
The study is currently expected to finish around August 2026.
The main measurement is taken over: Pre-exercise and 10, 20, and 30-minutes post-exercise.
From the trial registry
Built from these fields:
- designModule.enrollmentInfo.count
- statusModule.completionDateStruct.date
- outcomesModule.primaryOutcomes[].timeFrame
What the study measures
Systolic pulmonary artery pressure — measured over Pre-exercise and 10, 20, and 30-minutes post-exercise.
From the trial registry
Built from these fields:
- outcomesModule.primaryOutcomes[].measure
- outcomesModule.primaryOutcomes[].timeFrame
Source: NCT07285031 on ClinicalTrials.gov. The full registry text is further down this page — this summary never replaces it.
Not medical advice. What do these terms mean?
What is being tested — in plain terms
About Diphenhydramine hydrochlorideDrug
H1 receptor antagonist: 50mg Diphenhydramine Hydrochloride
From the trial registry — its own words, unedited.
What a drug is here: A medicine — a chemical or small-molecule treatment — given as the thing being studied.
Read the full explanation → · in clinical review
About PlaceboOther
Placebo
From the trial registry — its own words, unedited.
What a other is here: An intervention the registry did not place in another category.
Read the full explanation → · in clinical review
About Exercise BoutOther
Participants will complete a total of three 5-minute high intensity exercise intervals, interspersed with 5-minute lower intensity exercise bouts (4 total), for a total of 35 minutes.
From the trial registry — its own words, unedited.
What a other is here: An intervention the registry did not place in another category.
Read the full explanation → · in clinical review
Common questions
Answered from this trial’s registry record. Where the record doesn’t say, these answers say so rather than filling the gap.
Am I eligible for this trial?
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part. Concord cannot make that determination, and neither can any tool that has not examined you.
What the study lists: an age range of 19 years to 39 years.
The full inclusionInclusion criteriaThe things you must have or be for a study to consider you.Read more → and exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more → are published on this page, exactly as the study team wrote them.
The useful next step is to bring this trial to your doctor. Answering a few questions first gives them something concrete to review.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.eligibilityCriteria
Is there a placebo?
Yes. This study includes a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group — a dummy treatment with no active medicine in it.
From the trial registry
- armsInterventionsModule.armGroups[].type
Would I know which treatment I am getting?
You, the study team, and the people analysing the results would all be kept unaware of which group you are in until the study ends.
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
From the trial registry
- designModule.designInfo.maskingInfo.masking
- designModule.designInfo.allocation
Who can join?
The study lists an age range of 19 years to 39 years.
It is open to people of any sex.
It accepts healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more → as well as people with the condition.
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can confirm whether a particular person can take part.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How long would this take?
The study's main measurement is taken over: Pre-exercise and 10, 20, and 30-minutes post-exercise..
The study as a whole is currently expected to finish around 2026-08.
How long any one person takes part can differ from the study length. The study team can tell you what the schedule looks like in practice.
From the trial registry
- outcomesModule.primaryOutcomes[].timeFrame
- statusModule.completionDateStruct.date
How many people are taking part?
The study aims to enrol about 20 people.
From the trial registry
- designModule.enrollmentInfo.count
Where is this happening?
This study lists one location: Kelowna, British Columbia, Canada.
Sites can open and close during a study, so confirm with the team before travelling.
From the trial registry
- trial_locations
About This Trial
When we exercise, more blood flow goes to our muscles, challenging our blood vessels. Following exercise, blood flow remains elevated and seems to be the reason for many of the positive cardiovascular benefits that occur with exercise. When the actions of histamine, a molecule primarily known for its role in allergies, are blocked, there is an attenuated blood flow response following exercise. However, this effect has never been studied in the blood vessels that supply our lungs. The purpose of this study is to examine the effects of histamines on pulmonary hemodynamics following exercise.
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See if this trial could fit youThis page is for informational purposes only and does not constitute medical advice. Clinical trial eligibility can only be determined by the trial site after proper screening. Trial information is sourced from ClinicalTrials.gov and may not reflect the most current status. Always consult your healthcare provider before making decisions about clinical trial participation.