How histamine affects blood flow to the lungs after exercise.

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

Healthy adults will visit a lab three times to complete an exercise bout while researchers measure pulmonary blood flow and pressures using ultrasound/echocardiography. On intervention visits participants will receive either diphenhydramine (an antihistamine) or a placebo and measurements will be repeated before and after exercise. The design compares pulmonary hemodynamic responses with and without histamine blockade to see if histamine contributes to sustained post-exercise pulmonary blood flow. The study excludes people with heart, lung, or metabolic disease, smokers, those taking medications, pregnant or breastfeeding individuals, and anyone without usable tricuspid regurgitation for the primary measurement.

Why it matters

Who can join: the full rules

Inclusion Criteria:

1. Age: 19 - 39.
2. Willing to visit the lab on 3 separate occasions.

Exclusion Criteria:

1. Previously diagnosed heart condition,
2. Previously diagnosed lung condition (including asthma),
3. Previously diagnosed metabolic condition,
4. Currently smokers (cigarettes, electronic cigarettes, cannabis) or who have smoked within the last 3 months,
5. Resting blood pressure \>140/90 mmHg,
6. Unable to obtain appropriate quality ultrasound images of the heart.,
7. Individuals without tricuspid regurgitation at rest to allow assessment of the primary outcome,
8. Pregnant or trying to become pregnant,
9. Breastfeeding,
10. Chronically take antihistamines (i.e. daily),
11. History of adverse reactions to antihistamines,
12. Never taken antihistamines previously,
13. Currently taking any medications (including oral contraceptives).

Where it's running

• University of British Columbia
  Kelowna, British Columbia, Canada Recruiting

Study contacts

• Study coordinator: Neil Eves, PhD
• Email: neil.eves@ubc.ca
• Phone: (250) 807-9676

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.