Fixed Dose Flavonoid Isoquercetin on Thrombo-Inflammatory Biomarkers in Subjects With Stable Sickle Cell Disease

    Not Recruiting
  • End date
    Oct 28, 2022
  • participants needed
  • sponsor
    National Heart, Lung, and Blood Institute (NHLBI)
Updated on 27 June 2022
blood transfusion
vaso-occlusive crisis



Sickle cell disease (SCD) is an inherited hemoglobin disorder. People with SCD have an increased chance for getting blood clots. Researchers want to see if a dietary supplement called Isoquercetin can decrease levels of inflammation and blood clotting in people with SCD.


To see how Isoquercetin works in people with SCD.


Adults age 18-70 years old who have SCD and are in a steady-state (have not experienced a pain crisis in the last 60 days and, if taking hydroxyurea, have not had a dose change in the past 90 days).


Participants will be screened with a physical exam, medical history, medicine review, and blood tests.

Participants may have a peripheral arterial tonometry (Endo-Pat) test to check the function of their blood vessels. For this, a thimble-shaped cup is placed on their finger and a blood pressure cuff is placed on their arm.

Participants will be put in 1 of 2 treatment groups. They will take 4 capsules of Isoquercetin or placebo all at once, by mouth, every day for 4 weeks. They will get a pill dispenser and keep a medicine diary.

Participants will take folic acid once a day.

Participants will have an end-of-study visit. They will discuss any side effects and repeat some of the screening tests. They may have an Endo-Pat test.

About a month after the last study visit, participants will be contacted by phone to see if they have any side effects. Those who do may have a follow-up visit. At this visit, they may have blood tests.

Participation will last from 8 to 12 weeks.


Sickle Cell Disease (SCD) is an inherited monogenic hemoglobin disorder caused by a mutation in the gene encoding the beta globin subunit of adult hemoglobin (HbA) resulting in a substitution of valine for glutamic acid at position 6 and thus producing hemoglobin S (HbS). When deoxygenated, HbS polymerizes, rendering the red cell rigid, viscous, and abnormally adherent to the capillary endothelium. This impedes blood flow in the microcirculation, causing ischemia and microinfarcts that lead to painful crises, cerebrovascular stroke, renal impairment, retinopathy and other end-organ damage. The current scientific literature currently recognizes the contribution of an acquired hypercoagulable state in SCD to vascular pathobiology, chronic organ dysfunction, and mortality.

Similar to cancer, sickle cell disease is associated with an acquired hypercoagulable state and exhibits a high prevalence of incident and recurrent venous thromboembolism (VTE). Elevated levels of the procoagulant protein tissue factor and its activator, protein disulfide isomerase in humans with SCD suggest a causal role for thrombogenesis. In cancer patients, pharmacological inhibition of plasma PDI with Isoquercetin (IQ) led to a reduction in VTE biomarkers and VTE recurrence. These findings provide support to test the hypothesis that Isoquercetin in sickle cell disease would diminish thrombo-inflammatory VTE biomarkers and attenuate the associated hypercoagulable state.

Condition SCD
Treatment Placebo, Isoquercetin
Clinical Study IdentifierNCT04514510
SponsorNational Heart, Lung, and Blood Institute (NHLBI)
Last Modified on27 June 2022

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note