A Phase 4 interventional study of OHCit- standard dose and Potassium Citrate in Calcium Phosphate Kidney Stones, sponsored by University of Texas Southwestern Medical Center. Recruiting at 1 site in United States. Open to participants aged 21 Years to 99 Years. Per ClinicalTrials.gov, last updated 2026-06-02.
Sponsored by University of Texas Southwestern Medical Center · Phase 4, Interventional, and Prevention
This study tests whether hydroxycitrate, a molecule closely related to citrate, can reduce calcium phosphate stone recurrence.
In this double-blind, placebo-controlled, randomized, crossover study, each participant will undergo 4 phases of study, with the order randomized by a blocked randomization scheme. The 4 phases will be Placebo, Super CitriMax (hydroxycitrate) OHCit low dose, OHCit standard dose, or Potassium Citrate. Randomization will be stratified based on sex, concomitant thiazide use, and concomitant alkali use.
Each phase will be 1 week in duration, during which subjects will take assigned study medications. A minimum 1-week washout period will be imposed between phases. During the first 2 days of each phase, subjects will be instructed to adhere to a prescribed diet. On the last 5 days of each phase, subjects will be kept on a constant metabolic diet. Use of metabolic diet is essential to eliminate confounders that could occur from changes in dietary intake across phases. During the final two study days (days 6-7), two 24-hr urines will be collected for urine biochemistry and crystallization studies. Fasting blood will be obtained at the end of the last urine collection.
Study Medications: Subjects will receive three tablets twice daily during each phase. These will consist of either placebo, Potassium Citrate (KCit), or Super CitriMax (OHCit). Study tablets will be prepared by a compounding pharmacy, with placebo tablets similar in appearance and size to the active medication tablets.
253 studies on the registry are indexed under Urolithiasis; 67 are open to participants now.
This study's planned enrollment of 25 is below the median of 100 across 182 interventional studies indexed under Urolithiasis.
Browse Urolithiasis studies →University of Texas Southwestern Medical Center is the lead sponsor of 1,010 studies on the registry; 199 are open to participants now.
Of its 139 completed or terminated interventional studies of FDA-regulated products, 105 (76%) 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.
- Calcium Phosphate stone formers
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.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Potassium Citrate KCit 10 mEq 2 tabs, twice daily and Placebo 1 tab, twice daily Total Daily Dose: Citrate 40 mEq/d
Drug: Potassium Citrate
Super CitriMax 7 mEq 3 tabs, twice daily Total Daily Dose: OHCit 42 mEq/d
Dietary Supplement: OHCit- standard dose
Super CitriMax 7 mEq 2 tabs, twice daily And Placebo 1 tab, twice daily Total Daily Dose: OHCit 28 mEq/d
Dietary Supplement: OHCit- low dose
Placebo 3 tablets twice daily Total Daily Dose: None
Drug: Placebo
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.
Also known as: Super Citrimax
10 mEq Extended-release tablets for oral use
Also known as: Urocit®-K
Placebo
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.
Also known as: Super Citrimax
Formation product (FP) for Calcium Phosphate
FP is obtained by adding increasing amounts of Calcium Chloride (CaCl2) to a series of urine aliquots maintained at constant pH for 2 hours, and is identified by the point at which calcium phosphate (CaP) precipitates as detected by an absorbance microplate reader. Calculated supersaturation using \[Calcium\] and \[Phosphate\] at that point represents FP.
Time frame: After 1 week of treatment
Crystal growth of Calcium Phosphate
We will assess crystal growth (CG) of CaP after seeding urine with a small amount of brushite (0.25 mg/ml urine) and incubating at 37°C for 3 hours (representing steady state) under constant stirring. A decrement in \[Calcium\]×\[Phosphate\] after seeding signifies crystal growth, while a \[Calcium\]×\[Phosphate\] increment represents crystal dissolution.
Time frame: After 1 week of treatment
Calcium Phosphate supersaturation
Supersaturation of calcium phosphate will be assessed by Joint Expert Speciation System (JESS).
Time frame: After 1 week of treatment
Started Dec 2023 (actual). Primary completion is estimated for May 2028, 53 months after the start.
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