Trial Outcomes & Findings for Phentermine/Topiramate for Uric Acid Stones (NCT NCT04621929)
NCT ID: NCT04621929
Last Updated: 2026-01-30
Results Overview
Stone perimeter within each cut of CT image was outlined using semiautomated volume tool (region of interest pen tool, CT software "Visage Imaging") and tallied to calculate stone volume (mm\^3) for each individual stone and recorded from right and left kidney from all study participants at baseline CT and at end of study CT (18 months)
Recruitment status
COMPLETED
Study phase
PHASE3
Target enrollment
19 participants
Primary outcome timeframe
Baseline, 18 months
Results posted on
2026-01-30
Participant Flow
Participant milestones
| Measure |
Allocated to Intervention/Treatment
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Overall Study
STARTED
|
13
|
6
|
|
Overall Study
COMPLETED
|
10
|
5
|
|
Overall Study
NOT COMPLETED
|
3
|
1
|
Reasons for withdrawal
| Measure |
Allocated to Intervention/Treatment
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Overall Study
Withdrawal by Subject
|
3
|
1
|
Baseline Characteristics
Phentermine/Topiramate for Uric Acid Stones
Baseline characteristics by cohort
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
Total
n=19 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Continuous
|
58.80 years
STANDARD_DEVIATION 9.5 • n=35 Participants
|
69.20 years
STANDARD_DEVIATION 6.4 • n=4328 Participants
|
64 years
STANDARD_DEVIATION 7.95 • n=8687 Participants
|
|
Sex: Female, Male
Female
|
4 Participants
n=35 Participants
|
2 Participants
n=4328 Participants
|
6 Participants
n=8687 Participants
|
|
Sex: Female, Male
Male
|
9 Participants
n=35 Participants
|
4 Participants
n=4328 Participants
|
13 Participants
n=8687 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
13 Participants
n=35 Participants
|
6 Participants
n=4328 Participants
|
19 Participants
n=8687 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
Asian
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
Black or African American
|
1 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
1 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
White
|
11 Participants
n=35 Participants
|
6 Participants
n=4328 Participants
|
17 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
More than one race
|
1 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
1 Participants
n=8687 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=35 Participants
|
0 Participants
n=4328 Participants
|
0 Participants
n=8687 Participants
|
|
Region of Enrollment
United States
|
13 participants
n=35 Participants
|
6 participants
n=4328 Participants
|
19 participants
n=8687 Participants
|
PRIMARY outcome
Timeframe: Baseline, 18 monthsStone perimeter within each cut of CT image was outlined using semiautomated volume tool (region of interest pen tool, CT software "Visage Imaging") and tallied to calculate stone volume (mm\^3) for each individual stone and recorded from right and left kidney from all study participants at baseline CT and at end of study CT (18 months)
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Kidney Stone Size (mm^3) Determined by Non-contrast CAT Scan
Baseline
|
6540 mm^3
Standard Deviation 10430
|
4650 mm^3
Standard Deviation 6064
|
|
Kidney Stone Size (mm^3) Determined by Non-contrast CAT Scan
End of Study (18 months)
|
3120 mm^3
Standard Deviation 5158
|
5041 mm^3
Standard Deviation 7043
|
SECONDARY outcome
Timeframe: Baseline, 18 monthstotal weight (baseline and end of study)
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Weight (kg)
Baseline
|
121.4 kg
Standard Deviation 24
|
101.2 kg
Standard Deviation 23
|
|
Weight (kg)
End of Study (18 months)
|
111.2 kg
Standard Deviation 24
|
104.1 kg
Standard Deviation 26
|
SECONDARY outcome
Timeframe: Baseline, 18 monthsurine pH (baseline and end of study). The pH scale ranges from 0 to 14. A pH of 7 is neutral. A pH less than 7 is acidic. A pH greater than 7 is basic.
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Urinary pH Parameters
Baseline
|
5.3 unitless
Standard Deviation 0.2
|
5.3 unitless
Standard Deviation 0.2
|
|
Urinary pH Parameters
End of Study (18 months)
|
6.2 unitless
Standard Deviation 0.5
|
5.5 unitless
Standard Deviation 0.5
|
SECONDARY outcome
Timeframe: Baseline, 18 months%A1c (baseline and end of study)
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
%Hemoglobin A1c
Baseline
|
6.6 percentage of glycated hemoglobin
Standard Deviation 1.4
|
6.2 percentage of glycated hemoglobin
Standard Deviation 0.9
|
|
%Hemoglobin A1c
End of Study (18 months)
|
6.4 percentage of glycated hemoglobin
Standard Deviation 1.5
|
6.7 percentage of glycated hemoglobin
Standard Deviation 1.5
|
SECONDARY outcome
Timeframe: Baseline, 18 monthsurinary citrate (baseline and end of study)
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Urinary Citrate Parameters
End of Study
|
309 mg/day
Standard Deviation 81
|
951 mg/day
Standard Deviation 782
|
|
Urinary Citrate Parameters
Baseline
|
634 mg/day
Standard Deviation 289
|
673 mg/day
Standard Deviation 526
|
SECONDARY outcome
Timeframe: Baseline, 18 monthsurinary calcium (baseline and end of study)
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Urinary Calcium Parameters
Baseline
|
172 mg/day
Standard Deviation 58
|
154 mg/day
Standard Deviation 95
|
|
Urinary Calcium Parameters
End of Study (18 months)
|
224 mg/day
Standard Deviation 45
|
167 mg/day
Standard Deviation 122
|
SECONDARY outcome
Timeframe: Baseline, 18 monthsUrinary uric acid SS (before and end of study). Urinary Uric Acid Supersaturation (SS) is not measured in a specific unit, as it is a ratio. Result below 1: The urine is undersaturated, meaning that crystals are more likely to dissolve than form. Result equal to 1: The urine is in equilibrium with uric acid, so crystals will not grow or shrink. Result above 1: The urine is supersaturated, and the risk for crystals to form and grow is increased. A higher value indicates a greater risk.
Outcome measures
| Measure |
Allocated to Intervention/Treatment
n=13 Participants
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 Participants
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Urinary Uric Acid Supersaturation (SS)
Baseline
|
2.2 unitless
Standard Deviation 1.1
|
2.4 unitless
Standard Deviation 1.0
|
|
Urinary Uric Acid Supersaturation (SS)
End of Study (18 months)
|
0.7 unitless
Standard Deviation 1.1
|
1.8 unitless
Standard Deviation 1.1
|
Adverse Events
Allocated to Intervention/Treatment
Serious events: 0 serious events
Other events: 12 other events
Deaths: 0 deaths
Allocated to Pragmatic Control
Serious events: 0 serious events
Other events: 5 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
| Measure |
Allocated to Intervention/Treatment
n=13 participants at risk
Daily phentermine/topiramate x 18 months
Phentermine / Topiramate Oral Product: All participants in the experimental group will receive oral generic tablet phentermine (18.75 or 37.5 mg dose) and topiramate (daily 100 mg or 150 mg dose)
|
Allocated to Pragmatic Control
n=6 participants at risk
Remain on their current regimen
Citrate Salts, Allopurinol, Diet: Control participants will complete initial visit requirements and study enrollment and will be maintained on their current therapy.
|
|---|---|---|
|
Renal and urinary disorders
Kidney Stone Passage
|
23.1%
3/13 • Number of events 3 • 18 months
|
50.0%
3/6 • Number of events 3 • 18 months
|
|
Renal and urinary disorders
Kidney Stone Procedure
|
0.00%
0/13 • 18 months
|
33.3%
2/6 • Number of events 2 • 18 months
|
|
General disorders
Dizziness
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
General disorders
Dysgeusia
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Renal and urinary disorders
Erectile Dysfunction
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Endocrine disorders
Hypoglycemia
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Reproductive system and breast disorders
Menstrual Cycle Irregularity
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Cardiac disorders
New Onset Artrial Fibrillation
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Cardiac disorders
Tachycardia
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Injury, poisoning and procedural complications
Wrist Fracture
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
|
Renal and urinary disorders
Bladder Stone Surgery
|
7.7%
1/13 • Number of events 1 • 18 months
|
0.00%
0/6 • 18 months
|
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place