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NCT Number: NCT05005793

Effect of Alkali Therapy on Vascular and Graft Function in Kidney Transplant Recipients

Lower serum bicarbonate levels, even within the normal laboratory range, in kidney transplant recipients (KTRs) are associated with an increased risk of graft loss, cardiovascular events and mortality. Because acid retention is common in KTRs, it is plausible that alkali therapy in KTRs may also result in improved vascular and graft function. The investigators will perform a randomized, double-blinded, placebo-controlled, 12 month study in 120 KTRs to examine the effect of sodium bicarbonate therapy on surrogate markers of CVD and graft function. The overall hypothesis is that treatment with bicarbonate will improve indicators of vascular and graft function in KTRs by decreasing complement activation.

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Key information

Conditions

Metabolic Acidosis Acid-Base Imbalance Acidosis Cardiovascular Diseases Kidney Transplant; Complications Metabolic Diseases Nutritional and Metabolic Diseases Vascular Diseases

Age range

18 year–80 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

University of Colorado

Aurora, Colorado, 80045, United States

Location status: Recruiting

Location contact

Jessica Kendrick

CONTACT

[email protected]

303-724-4837

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age 18-80 years
  • Serum bicarbonate 16-24 mEq/L on 2 separate measurements (at least 1 day apart)
  • Kidney transplant received 1 year prior to randomization
  • eGFR ≥ 45 ml/min/1.73m2 by CKD-EPI equation
  • Blood pressure <130/80 mm Hg prior to randomization
  • BMI < 40 kg/m2 (FMD measurements can be inaccurate in severely obese patients).
  • Able to provide consent
  • Immunosuppression regimen consisting of tacrolimus, mycophenolate mofetil and prednisone (95% of patients at University of Colorado are on this regimen)
  • Stable immunosuppression regimen for at least three months prior to randomization
  • Stable anti-hypertensive regimen for at least one month prior to randomization
  • Not taking medications that interact with agents administered during experimental sessions (e.g. sildenafil interacts with nitroglycerin).

Exclusion criteria

  • Significant comorbid conditions that lead the investigator to conclude that life expectancy is less than 1 year
  • Use of chronic daily oral alkali within the last 3 months (including sodium bicarbonate, calcium carbonate or baking soda)
  • Uncontrolled hypertension
  • Serum potassium < 3.3 or ≥ 5.5 mEq/L at screening
  • New York Heart Association Class 3 or 4 heart failure symptoms, known EF ≤30%, or hospital admission for heart failure within the past 3 months
  • Nephrotic range proteinuria (urine complement activation fragment measurements may not be accurate with severe proteinuria)
  • Factors judged to limit adherence to interventions
  • Current participation in another research study
  • Pregnancy or planning to become pregnant or currently breastfeeding
  • Chronic use of supplemental oxygen
  • Use of anticoagulants

Treatment and study plan

Sodium bicarbonate

Drug

Oral sodium bicarbonate at 0.5 mEq/kg-lean body weight/day

Placebo

Drug

Placebo at 0.5 mEq/kg-lean body weight/day

Primary outcomes

  1. Change in Brachial artery flow mediated dilation at 12 months

    Time frame: Baseline and 12 months

    Brachial artery FMD will be determined using high-resolution ultrasonographyECG-gated end-diastolic ultrasound images and Doppler flow of the brachial artery will be acquired during baseline and FMD conditions. For FMD, reactive hyperemia will be produced by inflating a pediatric BP cuff around the forearm to 250 mmHg for 5 minutes followed by rapid deflation.

Secondary outcomes

  1. Change in Large elastic artery stiffness and compliance at 12 months

    Time frame: Baseline and 12 months

    transcutaneous custom tonometers (Noninvasive hemodynamics Workstation, Cardiovascular Engineering Inc., Norwood, MA) will be positioned at the aorta and femoral artery to measure aortic pulse wave velocity.

  2. Change in Tubular atrophy at 12 months

    Time frame: Baseline and 12 months

    Kidney transplant biopsies will be performed. Morphometric analysis will be performed using trichrome and Sirius Red to determine tubular atrophy. All imaging will be done using an Aperio scanner.

  3. Change in participant plasma and urine complement activation fragment levels at 12 months

    Time frame: Baseline and 12 months

    Complement activation fragments (Ba, C4a, C3a, C5a, sC5b-9) will be measured at the University of Colorado Exsera Biolab located on the Anschutz Medical Campus.

  4. Change in interstitial fibrosis at 12 months

    Time frame: Baseline and 12 months.

    Kidney transplant biopsies will be performed. Morphometric analysis will be performed using trichrome and Sirius Red to determine interstitial fibrosis.

Study contacts

Contact information is provided by the study sponsor or research team.

Jessica Kendrick, MD MPH

CONTACT

[email protected]

3037244837

Sponsors and collaborators

Lead sponsor

University of Colorado, Denver

Other

Collaborators

  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Registry information

Official study title

Effect of Alkali Therapy on Vascular and Graft Function in Kidney Transplant

Important dates

Study start
2021
Primary completion
2026
Study completion
2026
First posted
Aug 16, 2021
Registry last updated
May 29, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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