Joshua Heiman, MD, on phentermine plus topiramate for uric acid stone prevention

Combination treatment with phentermine and topiramate may offer an option for uric acid stone prevention, according to data from the POuND OUT study (NCT04621929), which were presented at the 2025 American Urological Association Annual Meeting in Las Vegas, Nevada.

In an interview with Urology Times®, presenting author Joshua M. Heiman, MD, detailed key findings from the feasibility study.

In total, the study randomly assigned 19 patients in a 2:1 fashion to either combination phentermine/topiramate or to standard therapy. The median age of patients was 62 years.

Data showed that patients in the combination treatment arm demonstrated fewer stone procedures, lower HbA1c levels, and higher urine pH compared with those in the control arm.

Specifically, the increase in urine pH (from the end of study minus baseline) was +0.9 (±0.4) in the treatment arm vs +0.2 (±0.3) in the control arm. Further, HbA1c levels decreased by -0.6 (±0.9) in the treatment arm and increased by +0.4 (±0.8) in the control arm.

Heiman also added, “Patients who were on this medication, their stone volume decreased by greater than 50% when compared to the control group. It's pretty impressive, very remarkable, to see this drastic change in their stone volume while taking this medication.”

The treatment also appeared to be well-tolerated.

While promising, these data were only part of a feasibility study evaluating the combination. Further work is needed to assess this regimen in a wider range of patients with obesity and diabetes, according to the authors.

REFERENCE

1. Heiman JM, Canales MT, Terry RS, et al. The POuND OUT study: Phentermine and topiramate for uric acid stone prevention. J Urol. 2025;213(5S):e1155. doi:10.1097/01.JU.0001110128.62940.65.01