An Early Phase 1 interventional study of Ferrous sulfate 325mg in Right Ventricular Dysfunction and Hypoxia, sponsored by University of Colorado, Denver. Not yet recruiting at 1 site in United States. Open to participants aged 18 Years to 60 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-04-29.
Sponsored by University of Colorado, Denver · Early Phase 1, Interventional, and Prevention
The purpose of this study is to determine if taking iron supplement pills improves exercise performance in low-oxygen conditions.
Hypoxia (low oxygen) causes the blood vessels in the lungs to constrict (hypoxic pulmonary vasoconstriction). This increases the pressure (afterload) the right ventricle faces as it pumps blood to the lungs. Increased right ventricular afterload during hypoxia may compromise exercise capacity. Intravenous iron administration prior to hypoxic exposure has been shown to blunt the hypoxia-induced increase in right ventricular afterload. This may be through iron's action in the Hypoxia Inducible Factor (HIF) pathway. Iron is a cofactor for prolyl hydroxylases that degrade HIF subunits and thus may "turn off" HIF-related pathways of pulmonary artery vasoconstriction and remodeling. However, it is not known whether oral iron supplementation similarly reduces right ventricular afterload in hypoxia, or what impact iron has on right ventricular function and exercise capacity in hypoxia.
This is a human physiology study that will characterize the impact of oral iron supplementation on right ventricular function and exercise performance in hypoxia. It is a follow-up "sub-study" to a separate, "parent" study (NCT05272514) by the same investigators which evaluates resting and exertional right ventricular performance in normoxia and hypoxia in 10 healthy individuals. In this follow-up study, 5 individuals who completed the parent study will be eligible to enroll. As part of the parent study, participants will complete baseline echocardiography to assess right ventricular function and cardiopulmonary exercise testing to assess exercise performance in normoxia and hypoxia. After enrolling in this study, participants will take an oral iron supplement (ferrous sulfate 325 mg oral daily) for 30 days. They will then return for one visit. First, participants will complete submaximal exercise while breathing room air. Submaximal exercise will include 5 minutes each at 40% and 60% of baseline hypoxic (fraction of inspired oxygen [FiO2] 12%) maximal oxygen uptake (VO2max) achieved during parent study. After 10 minutes' rest, echocardiographic measurements will be obtained at upright rest with FiO2 21%, 17%, 15%, and 12% to characterize the impact of progressive hypoxia on resting right ventricular function. Participants will then repeat submaximal exercise tests at FiO2 12%, followed by a short period of recovery. Thereafter, participants will complete a symptom-limited cardiopulmonary exercise test at FiO2 12%. Measurements will include heart rate/rhythm, oxygen saturation, blood pressure, gas exchange parameters (oxygen uptake [VO2], carbon dioxide production [VCO2], and minute ventilation), rated perceived exertion and resting echocardiographic measurements.
90 studies on the registry are indexed under Ventricular Dysfunction, Right; 28 are open to participants now.
This study's planned enrollment of 5 is below the median of 60 across 38 interventional studies indexed under Ventricular Dysfunction, Right.
Browse Ventricular Dysfunction, Right studies →University of Colorado, Denver is the lead sponsor of 1,543 studies on the registry; 317 are open to participants now.
Of its 147 completed or terminated interventional studies of FDA-regulated products, 92 (63%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Five healthy participants will be enrolled. Baseline echocardiography and exercise data prior to oral iron supplementation will be obtained as part of the "parent" study to this study (NCT05272514).
Drug: Ferrous sulfate 325mg
The same five healthy participants will complete echocardiography and exercise testing after taking 30 days of oral iron supplementation.
Drug: Ferrous sulfate 325mg
Participants will take one tab of ferrous sulfate 325 mg (equivalent to 65 mg elemental iron) daily for 30 days.
Maximum workload
Workload in Watts at peak exercise on upright cycle ergometer
Time frame: Up to 1 hour
Maximal oxygen uptake
Maximal oxygen uptake at peak exercise (VO2max) in L/min
Time frame: Up to 1 hour
Oxygen saturation at peak exercise
Peripheral oxygen saturation (SpO2)
Time frame: Up to 1 hour
Submaximal Stage 1 workload
Workload in Watts at 40% x hypoxic VO2max (obtained during baseline hypoxic exercise test)
Time frame: Up to 1 hour
Submaximal Stage 2 workload
Workload in Watts at 60% x hypoxic VO2max (obtained during baseline hypoxic exercise test)
Time frame: Up to 1 hour
Ventilatory threshold
Oxygen uptake (VO2 in L/min) at which slope of VCO2/VO2 relationship increases
Time frame: Up to 1 hour
Tricuspid annular plane systolic excursion measured by echocardiography
In mm
Time frame: Up to 1 hour
Pulmonary artery systolic pressure measured by echocardiography
In mmHg
Time frame: Up to 1 hour
Plan to share: No
Start is estimated for Mar 2028; primary completion for Dec 2029, 21 months later.
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Studies of the drug tested here: Ferrous sulfate
Ventricular Dysfunction, Right →
University of Colorado, Denver →