Calcium Phosphate Kidney StonesPhase 4NCT06003348
Hydroxycitrate: A Novel Therapy for Calcium Phosphate Urinary Stones
A Phase 4 study testing OHCit- standard dose, Potassium Citrate and OHCit- low dose in people with Calcium Phosphate Kidney Stones, run by University of Texas Southwestern Medical Center at 1 site in United States.
Trial summary
This study tests whether hydroxycitrate, a molecule closely related to citrate, can reduce calcium phosphate stone recurrence. Read more about this study
- Who is it for?
- Ages 21 to 99 years
- Conditions the study is for
- Calcium Phosphate Kidney Stones
- What is being tested?
- OHCit- standard dose, Potassium Citrate and OHCit- low dose
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 25 participants
- Where
- 1 siteUnited States
- Study dates
- 13 Dec 2023to 31 Aug 2028
- Phase
- Phase 4
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 99 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Calcium Phosphate stone formers
Who cannot join
- History of recurrent urinary tract infections
- Chronic diarrhea
- Estimated Glomerular Filtration Rate (eGFR) < 45 ml/min/1.73 m2
- History of primary hyperparathyroidism
- Hypokalemia
- Hyperkalemia
- Pregnancy
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
UT Southwestern Medical Center
Dallas, Texas, 75390-8885
Naim M Maalouf, MD
About this study
This study tests whether hydroxycitrate, a molecule closely related to citrate, can reduce calcium phosphate stone recurrence.
Read the detailed description
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.
- Conditions
- Calcium Phosphate Kidney Stones
- Being tested
- OHCit- standard dose, Potassium Citrate, Placebo, OHCit- low dose
- Keywords
- Urolithiasis, Calcium phosphate, Citrate, Acid-base
- Medical subject headings
- Urolithiasis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
OHCit- standard doseDietary supplement
Also called Super Citrimax
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.
Potassium CitrateDrug
Also called Urocit®-K
10 mEq Extended-release tablets for oral use
PlaceboDrug
Placebo
OHCit- low doseDietary supplement
Also called Super Citrimax
Hydroxycitrate Over-the-counter supplement, not FDA approved or regulated.
| Study group | Role | What they receive |
|---|---|---|
| Potassium Citrate (Urocit®-K) | Active comparator | Potassium Citrate KCit 10 mEq 2 tabs, twice daily and Placebo 1 tab, twice daily Total Daily Dose: Citrate 40 mEq/d Receives: Drug: Potassium Citrate |
| Super CitriMax; OHCit-standard dose | Experimental | Super CitriMax 7 mEq 3 tabs, twice daily Total Daily Dose: OHCit 42 mEq/d Receives: Dietary Supplement: OHCit- standard dose |
| Super CitriMax; OHCit-low dose | Experimental | Super CitriMax 7 mEq 2 tabs, twice daily And Placebo 1 tab, twice daily Total Daily Dose: OHCit 28 mEq/d Receives: Dietary Supplement: OHCit- low dose |
| Placebo | Placebo comparator | Placebo 3 tablets twice daily Total Daily Dose: None Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: After 1 week of treatment
Secondary outcomes (2)
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.
Measured: After 1 week of treatment
Calcium Phosphate supersaturation
Supersaturation of calcium phosphate will be assessed by Joint Expert Speciation System (JESS).
Measured: After 1 week of treatment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Aug 2023
- Study start13 Dec 2023
- Primary completion31 May 2028 (estimated)
- Study completion31 Aug 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Calcium Phosphate Kidney StonesStudies of the same condition, open and under way.
- More trials run by University of Texas Southwestern Medical CenterThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- 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 (OHCit) low dose, Super CitriMax (OHCit) standard dose, or Potassium Citrate. Randomization will be stratified based on sex, concomitant thiazide use, and concomitant alkali use.
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 25 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Texas Southwestern Medical Center
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Naim Maalouf, University of Texas Southwestern Medical Center
- Investigators
- NAIM M MAALOUF, Principal investigator, University of Texas Southwestern Medical Center
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06003348
- Sponsor's protocol ID
- 2023-0339
- Status last verified
- Jun 2026
- First submitted
- 14 Aug 2023
- Last updated
- 2 Jun 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Hydroxycitrate: A Novel Therapy for Calcium Phosphate Urinary Stones
- ClinicalTrials.gov ID
- NCT06003348
- Acronym / sponsor ID
- 2023-0339
- Conditions
- Calcium Phosphate Kidney Stones
- Keywords
- Urolithiasis, Calcium phosphate, Citrate, Acid-base
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 25 participants (estimated)
- Lead sponsor
- University of Texas Southwestern Medical CenterUniversity, hospital or other
- Study start
- 13 Dec 2023 (actual)
- Primary completion
- 31 May 2028 (estimated)
- Study completion
- 31 Aug 2028 (estimated)
- First posted
- 21 Aug 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study tests whether hydroxycitrate, a molecule closely related to citrate, can reduce calcium phosphate stone recurrence.
Detailed description
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.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 4
- Model description
- 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 (OHCit) low dose, Super CitriMax (OHCit) standard dose, or Potassium Citrate. Randomization will be stratified based on sex, concomitant thiazide use, and concomitant alkali use.
| Arm | Type | Receives |
|---|---|---|
| Potassium Citrate (Urocit®-K) | Active comparator | Drug: Potassium CitratePotassium Citrate KCit 10 mEq 2 tabs, twice daily and Placebo 1 tab, twice daily Total Daily Dose: Citrate 40 mEq/d |
| Super CitriMax; OHCit-standard dose | Experimental | Dietary Supplement: OHCit- standard doseSuper CitriMax 7 mEq 3 tabs, twice daily Total Daily Dose: OHCit 42 mEq/d |
| Super CitriMax; OHCit-low dose | Experimental | Dietary Supplement: OHCit- low doseSuper CitriMax 7 mEq 2 tabs, twice daily And Placebo 1 tab, twice daily Total Daily Dose: OHCit 28 mEq/d |
| Placebo | Placebo comparator | Drug: PlaceboPlacebo 3 tablets twice daily Total Daily Dose: None |
Who may qualify
- Ages
- 21 to 99 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Calcium Phosphate stone formers
Key exclusion criteria (7 listed)
- History of recurrent urinary tract infections
- Chronic diarrhea
- Estimated Glomerular Filtration Rate (eGFR) < 45 ml/min/1.73 m2
- History of primary hyperparathyroidism
- Hypokalemia
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| OHCit- standard doseAlso: Super CitrimaxHydroxycitrate Over-the-counter supplement, not FDA approved or regulated. | Dietary supplement | Super CitriMax; OHCit-standard dose |
| Potassium CitrateAlso: Urocit®-K10 mEq Extended-release tablets for oral use | Drug | Potassium Citrate (Urocit®-K) |
| PlaceboPlacebo | Drug | Placebo |
| OHCit- low doseAlso: Super CitrimaxHydroxycitrate Over-the-counter supplement, not FDA approved or regulated. | Dietary supplement | Super CitriMax; OHCit-low dose |
Primary outcome
Formation product (FP) for Calcium Phosphate
Time frame: After 1 week of treatment
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.
2 secondary outcomes
Crystal growth of Calcium Phosphate
Time frame: After 1 week of treatment
Calcium Phosphate supersaturation
Time frame: After 1 week of treatment
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 2 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
NAIM M MAALOUF principal investigator
University of Texas Southwestern Medical Center
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing OHCit- standard dose, Potassium Citrate and OHCit- low dose in people with Calcium Phosphate Kidney Stones, run by University of Texas Southwestern Medical Center at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 7 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 2 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact NAIM M MAALOUF, MD (214/648-2954, naim.maalouf@utsouthwestern.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Formation product (FP) for Calcium Phosphate (time frame: After 1 week of treatment). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Jun 2026.