Histamines and Central Hemodynamics
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Diphenhydramine hydrochloride, Placebo, Exercise Bout.
- Who it may be relevant to
- Registry conditions: Histamine, Exercise. Basic parameters: 19 years — 39 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Canada
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
Unsure about the terms? Read our patient guide →
Official title
The Role of Histamines on Central Hemodynamics
Overview
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.
Interventions
- Drug Diphenhydramine hydrochloride
H1 receptor antagonist: 50mg Diphenhydramine Hydrochloride - Other Placebo
Placebo - Other 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.
Primary outcome measures
- Systolic pulmonary artery pressure [Time frame: Pre-exercise and 10, 20, and 30-minutes post-exercise.]
Secondary outcome measures (4)
- Tricuspid annular plane systolic displacement [Time frame: Pre-exercise and 0, 10, 20, 30, 45, and 60 minutes post-exercise.]
- Right ventricular stroke volume [Time frame: Pre-exercise and 0, 10, 20, 30, 45, and 60-minutes post-exercise.]
- Femoral artery blood flow [Time frame: Pre-exercise and 0, 10, 20, 30, 45, and 60-minutes post-exercise.]
- Mean arterial systemic pressure [Time frame: Pre-exercise and 0, 10, 20, 30, 45, and 60-minutes post-exercise.]
Eligibility criteria
Inclusion criteria
- Age: 19 - 39.
- Willing to visit the lab on 3 separate occasions.
Exclusion criteria
- Previously diagnosed heart condition,
- Previously diagnosed lung condition (including asthma),
- Previously diagnosed metabolic condition,
- Currently smokers (cigarettes, electronic cigarettes, cannabis) or who have smoked within the last 3 months,
- 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 outcome,
- Pregnant or trying to become pregnant,
- Breastfeeding,
- Chronically take antihistamines (i.e. daily),
- History of adverse reactions to antihistamines,
- Never taken antihistamines previously,
- Currently taking any medications (including oral contraceptives).
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Triple blind
- Primary purpose
- Basic science
Study locations
Canada · 1 center
- University of British Columbia — Kelowna
Identifiers
NCT: NCT07285031 · H25-01909