CompletedPhase 2

Phentermine/Topiramate for Uric Acid Stones

United States19 participantsStarted 2021-03-31

Plain-language summary

The investigator proposes an 18 month, feasibility pilot study, randomizing obese and diabetic individuals with pure uric acid nephrolithiasis (UAN) or mixed calcium oxalate (CO) UAN to either phentermine/topiramate or a pragmatic control group who will remain on their standard medication regimen (citrate salts, allopurinol, diet, etc.).

Who can participate

Age range

18 Years – 75 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * have recurrent pure uric acid nephrolithiasis (UAN) or mixed calcium oxalate (CO)/UAN. Recurrent stone disease is defined as at least two spontaneous kidney stone passages, two previous kidney stone procedures, or one previous stone passage and one previous procedure. Pure UAN is defined as at least one previous stone analysis demonstrating 100% uric acid mineral content. Mixed COUAN will be defined as at least one previous stone analysis with any mix of uric acid ≥80% and ≤20% calcium oxalate. If participant has more than one stone analysis, the most recent will be considered the current stone type. * have obesity, defined as BMI \> 30 kg/m2. * have type 2 diabetes mellitus or pre-diabetes, defined as previously diagnosed by laboratory testing (hemoglobin A1c, fasting plasma glucose, or oral glucose tolerance test) or as demonstrated by use of anti-hyperglycemic medications or insulin. * have at least one 24-hour urine study off medications demonstrating urine pH \< 5.8 or a study 24-hr urine demonstrating urine pH \< 5.8 Exclusion Criteria: * contraindications to topiramate, including: recurrent major depression, current substantial depressive symptoms, uncontrolled depression by PHQ 9 score \>= 10, history of suicidal ideation or behavior with intent to act (versus exclude those with depression); current pregnancy or attempting to conceive; pre-existing chronic kidney disease with eGFR \< 60 at time of enrollment; active cancer or active treatment …

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1This trial tested phentermine/topiramate — a weight-loss medication combination — to see if it could shrink uric acid kidney stones in people with obesity or diabetes. Since the trial is now completed, has the results data been published yet, and what did it actually show about whether stones got smaller?
2Topiramate is already sometimes used to prevent certain kidney stones, but this trial was testing it in combination with phentermine specifically for uric acid stones — can you explain how that combination might work differently, and whether that approach makes sense for my particular type of stone?
3Since this was a Phase 2 trial, the main goal was still establishing whether this treatment shows enough promise to study further — does that mean there's limited safety and effectiveness data compared to an established treatment, and would a more proven approach be a better fit for me right now?
4This trial enrolled people with obesity alongside conditions like Type 2 diabetes or pre-diabetes — given my own health profile, would the risks of adding a stimulant-based weight-loss drug like phentermine be appropriate to consider in my case?
5If the results from this completed trial were promising, is there a follow-up Phase 3 study or any clinical pathway being developed that might be relevant to discuss as a future option for me?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Kidney Stone Size (mm^3) Determined by Non-contrast CAT Scan

Timeframe: Baseline, 18 months

Trial details

NCT IDNCT04621929

SponsorUniversity of Florida

Sponsor typeOTHER

Study typeINTERVENTIONAL

Primary completion2024-11-14

Results submitted2025-11-19

View on ClinicalTrials.gov More Obesity trials