Trial Outcomes & Findings for Pharmacokinetics and Pharmacodynamics of Topiramate for Weight Loss in Youth: PHARMATOP (NCT NCT04986631)
NCT ID: NCT04986631
Last Updated: 2026-08-24
Results Overview
Percent change in body mass index (BMI) from baseline to 14 weeks (mean change from baseline to 14 weeks of follow up, analysis using paired t-tests)
Recruitment status
COMPLETED
Study phase
EARLY_PHASE1
Target enrollment
65 participants
Primary outcome timeframe
14 Weeks
Results posted on
2026-08-24
Participant Flow
Participants were recruited directly from our pediatric weight management clinics by providers within the clinic. Participants were also recruited using IRB approved mailers and social media.
This was an open-label study in which all participants received topiramate (tablets) plus two health behavior and lifestyle intervention sessions throughout the study duration. For all participants, topiramate dose was titrated up by 25 mg increments to 75 mg daily (or maximum tolerated dose, i.e. 25 mg daily for week 1, 50 mg for week 2, and 75 mg daily for weeks 3-14).
Participant milestones
| Measure |
Topiramate
This was an open-label study in which all participants received topiramate (tablets) plus two health behavior and lifestyle intervention sessions. Topiramate was dosed 25 mg daily for week 1, 50 mg daily for week 2, and 75 mg daily for weeks 3-14.
|
|---|---|
|
Overall Study
STARTED
|
65
|
|
Overall Study
COMPLETED
|
59
|
|
Overall Study
NOT COMPLETED
|
6
|
Reasons for withdrawal
| Measure |
Topiramate
This was an open-label study in which all participants received topiramate (tablets) plus two health behavior and lifestyle intervention sessions. Topiramate was dosed 25 mg daily for week 1, 50 mg daily for week 2, and 75 mg daily for weeks 3-14.
|
|---|---|
|
Overall Study
Pregnancy
|
1
|
|
Overall Study
Withdrawal by Subject
|
2
|
|
Overall Study
Lost to Follow-up
|
3
|
Baseline Characteristics
Pharmacokinetics and Pharmacodynamics of Topiramate for Weight Loss in Youth: PHARMATOP
Baseline characteristics by cohort
| Measure |
Topiramate
n=65 Participants
This was an open-label study in which all participants received topiramate (tablets) plus two health behavior and lifestyle intervention sessions. Topiramate was dosed 25 mg daily for week 1, 50 mg daily for week 2, and 75 mg daily for weeks 3-14.
|
|---|---|
|
Age, Categorical
<=18 years
|
65 Participants
n=1541 Participants
|
|
Age, Categorical
Between 18 and 65 years
|
0 Participants
n=1541 Participants
|
|
Age, Categorical
>=65 years
|
0 Participants
n=1541 Participants
|
|
Sex: Female, Male
Female
|
35 Participants
n=1541 Participants
|
|
Sex: Female, Male
Male
|
30 Participants
n=1541 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
10 Participants
n=1541 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
55 Participants
n=1541 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
Asian
|
5 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
Black
|
4 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
More than One Race
|
4 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
Native Hawaiian or Other Pacific Islander
|
1 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
Other
|
4 Participants
n=1541 Participants
|
|
Race/Ethnicity, Customized
White
|
47 Participants
n=1541 Participants
|
|
Region of Enrollment
United States
|
65 participants
n=1541 Participants
|
PRIMARY outcome
Timeframe: 14 WeeksPercent change in body mass index (BMI) from baseline to 14 weeks (mean change from baseline to 14 weeks of follow up, analysis using paired t-tests)
Outcome measures
| Measure |
Topiramate
n=59 Participants
Individuals will receive 75 mg of topiramate daily. The dose will start at 25 mg daily for the first week. The second week participants will receive 50 mg daily. Starting at week 3 participants will take 75 mg daily.
Topiramate Tablets: Topiramate intervention
|
|---|---|
|
Percent BMI Change
|
-3.65 Percent change
Interval -5.02 to -2.28
|
Adverse Events
Topiramate
Serious events: 0 serious events
Other events: 51 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
| Measure |
Topiramate
n=65 participants at risk
This was an open-label study in which all participants received topiramate (tablets) plus two health behavior and lifestyle intervention sessions. Topiramate was dosed 25 mg daily for week 1, 50 mg daily for week 2, and 75 mg daily for weeks 3-14, which is the standard titration for individuals who start topiramate treatment. Because we did not alter the onboarding regiment for topiramate, adverse events were not collected per dose.
|
|---|---|
|
Nervous system disorders
Headache
|
15.4%
10/65 • Number of events 11 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Nervous system disorders
Dysgeusia
|
24.6%
16/65 • Number of events 18 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Psychiatric disorders
Agitation
|
7.7%
5/65 • Number of events 5 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Gastrointestinal disorders
Nausea
|
13.8%
9/65 • Number of events 9 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Gastrointestinal disorders
Constipation
|
9.2%
6/65 • Number of events 7 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Nervous system disorders
Paresthesia
|
52.3%
34/65 • Number of events 36 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Nervous system disorders
Sleepiness
|
27.7%
18/65 • Number of events 18 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Psychiatric disorders
Difficulty focusing
|
9.2%
6/65 • Number of events 6 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Psychiatric disorders
Depressed Mood
|
13.8%
9/65 • Number of events 11 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Psychiatric disorders
Insomnia
|
12.3%
8/65 • Number of events 8 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Nervous system disorders
Dizziness
|
13.8%
9/65 • Number of events 9 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Gastrointestinal disorders
Diarrhea
|
13.8%
9/65 • Number of events 10 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Gastrointestinal disorders
Vomiting
|
6.2%
4/65 • Number of events 4 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Infections and infestations
Respiratory Infection
|
13.8%
9/65 • Number of events 10 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
|
Gastrointestinal disorders
Dry Mouth
|
6.2%
4/65 • Number of events 4 • 14 weeks.
Participants in the topiramate arm followed a standardized dose titration schedule on file with the FDA: 25 mg daily during week 1, 50 mg daily during week 2, and 75 mg daily during weeks 3-14, as tolerated. Adverse events were collected and summarized for the topiramate treatment period overall and were not collected or summarized separately by dose level.
|
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place