Adjunct Phentermine + Topiramate After Bariatric Surgery in 12-24 Year Olds

Adjunctive Anti-Obesity Pharmacotherapy in Adolescents and Young Adults After Bariatric Surgery: A Randomized Controlled Pilot Study

The goal of this pilot study is to establish the feasibility and initial efficacy of the combination of phentermine and topiramate for adolescents and young adults who require additional risk reduction after bariatric surgery. This study will use a randomized, placebo-controlled, double-blinded design to evaluate an adjunctive 12-week intervention of phentermine + topiramate + standard of care vs. placebos + standard of care 6 months after bariatric surgery, among 12 to 24 year olds who don't achieve expected weight loss or who remain severely obese (n=10 total).

Study Overview

• Status: Completed
• Conditions: Adolescent; Obesity, Morbid; Drug Therapy; Bariatric Surgery; Young Adult
• Intervention / Treatment: Drug: Phentermine; Drug: Immediate Release Topiramate; Drug: Placebo for Phentermine; Drug: Placebo for Immediate Release Topiramate

• Study Type: Interventional
• Enrollment (Actual): 13
• Phase: Phase 2

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Aurora, Colorado, United States, 80045
      • Children's Hospital Colorado

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 12 years to 24 years (Child, Adult)
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Status post sleeve gastrectomy or roux-en-y gastric bypass
• At 6 months after bariatric surgery, has not achieved >= 26% decrease in weight from preoperative weight (within 1 week of surgery) OR remains severely obese (>=120% of 95th%ile or BMI >=35kg/m2 for 12-17yo; BMI >=35kg/m2 for 18-24yo)

Exclusion Criteria:

• Absolute contraindication to phentermine or topiramate (i.e. phentermine:

history of coronary artery disease, stroke, arrhythmia, congestive heart failure, uncontrolled hypertension), hypersensitivity to sympathomimetic amines, current or recent (within 14 days) use of monoamine oxidase inhibitors, glaucoma, or hyperthyroidism; topiramate: hypersensitivity to topiramate, history of nephrolithiasis)

• Concomitant use of phenytoin, carbamazepine, or carbonic anhydrase inhibitors (e.g. zonisamide, acetazolamide, or dichlorphenamide)
• Use of anti-obesity medication within 6 months of screening
• Initiation of a new medication associated with weight loss or gain within 30 days of screening
• Type 2 diabetes mellitus
• Hypothalamic obesity
• Unmanaged (e.g. without medications and/or psychotherapy) clinically significant (determined by a mental health professional using diagnostic instruments and/or clinical interview) depression or anxiety
• History of any suicidal behavior within 30 days of screening or any suicidal ideation with either some intent to act or with intent and a specific plan within 30 days of screening
• History of schizophrenia
• Severe hepatic impairment (ALT >10x upper limit of normal or known synthetic liver dysfunction)
• Moderate or severe renal impairment (GFR <30mL/min/1.73m2)
• Dosage change to hypertension, dyslipidemia, depression, or anxiety medication <4 weeks prior to study enrollment
• Contraception started <7 days prior to study enrollment
• Current pregnancy/plans to become pregnant within 16 weeks from study drug start date
• Females without a long acting reversible contraceptive (LARC) who do not commit to using 2 forms of birth control

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Phentermine & Topiramate; Phentermine- Formulation: 8mg scored tablet, Dosage/Frequency/Duration: 4mg x 7d then 8mg x 7d then 12mg x 7d then 16mg x 63d, taken once every morning + Immediate release topiramate- Formulation: 25mg tablet, Dosage/Frequency/Duration: 25mg x 7d then 50mg x 7d then 75mg x 7d then 100mg x 63d then 50mg x 7 days then 25mg x 7d, taken once every morning + Standard of Care (multidisciplinary postoperative bariatric surgery clinic visits)	Drug: Phentermine; Phentermine tablet; Other Names: Lomaira; Adipex-P; C045TQL4WP; 2-methyl-1-phenylpropan-2-amine; Drug: Immediate Release Topiramate; Topiramate tablet; Other Names: Topamax; 0H73WJJ391; [(3aS,5aR,8aR,8bS)-2,2,7,7-tetramethyl-5,5a,8a,8b-tetrahydrodi[1,3]dioxolo[4,5-a:5',3'-d]pyran-3a-yl]methyl sulfamate
Placebo Comparator: Placebo Drugs; Placebo Phentermine- Formulation: 8mg scored tablet, Dosage/Frequency/Duration: 4mg x 7d then 8mg x 7d then 12mg x 7d then 16mg x 63d, taken once every morning + Placebo Immediate release topiramate- Formulation: 25mg tablet, Dosage/Frequency/Duration: 25mg x 7d then 50mg x 7d then 75mg x 7d then 100mg x 63d then 50mg x 7 days then 25mg x 7d, taken once every morning + Standard of Care (multidisciplinary postoperative bariatric surgery clinic visits)	Drug: Placebo for Phentermine; Compounded tablet to mimic phentermine 8mg tablet; Drug: Placebo for Immediate Release Topiramate; Compounded tablet to mimic immediate release topiramate 25mg tablet

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dropout Rate	Number who do not complete the study divided by number enrolled	24 months
Enrollment Rate	(Number enrolled divided by number eligible) x 100	6 months
Number of Participants Adherent to Study Drugs	Presence of amphetamine in the urine at any study visit	12 weeks
Frequency of Adverse Events	Unique adverse events documented prior to unblinding. Adverse events were elicited using a standardized checklist during study phone calls and in-person study visits, laboratory monitoring, review of systems, vitals, physical exam, and mood/suicidality assessment using validated instruments at every study visit.	24 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Depression	The adolescent/young adult will complete the 20-item Center for Epidemiologic Studies Depression Scale (CES-D). Each item is rated on a 0 to 3 scale (positive items are reverse scored). Minimum score is 0 and maximum is 60. Higher scores indicate more depressive symptoms. Total score is calculated by summing each of the 20 individual items scores.	Baseline and 12 weeks
Percent BMI Change	(Baseline BMI - BMI at 12 weeks)/Baseline BMI x 100	Baseline and 12 weeks
Percent Weight Change	(Baseline weight - weight at 12 weeks)/Baseline weight x 100	Baseline and 12 weeks
Change in BMI Percent of the 95th%Ile	(Baseline BMI % of the 95th%ile - BMI % of the 95th%ile at 12 weeks)	Baseline and 12 weeks
Change in Heart Rate	(Heart rate at baseline - Heart rate at 12 weeks)	Baseline and 12 weeks
Change in Systolic Blood Pressure	Systolic blood pressure at baseline - Systolic blood pressure at 12 weeks	Baseline and 12 weeks
Change in Diastolic Blood Pressure	Diastolic blood pressure at baseline - Diastolic blood pressure at 12 weeks	Baseline and 12 weeks
Change in Total Cholesterol (mg/dL)	Total cholesterol at baseline - Total cholesterol at 12 weeks	Baseline and 12 weeks
Change in Triglycerides (mg/dL)	Triglycerides at baseline - Triglycerides at 12 weeks	Baseline and 12 weeks
Change in LDL Cholesterol (mg/dL)	LDL at baseline - LDL at 12 weeks	Baseline and 12 weeks
Change in HDL Cholesterol (mg/dL)	HDL at baseline - HDL at 12 weeks	Baseline and 12 weeks
Change in Alanine Aminotransferase (ALT) (U/L)	ALT at baseline - ALT at 12 weeks	Baseline and 12 weeks
Change in Hemoglobin A1c (HbA1c) (%)	HbA1c at baseline - HbA1c at 12 weeks	Baseline and 12 weeks
Change in % Fat Mass	% Fat mass at baseline - %Fat mass at 12 weeks measured by DEXA	Baseline and 12 weeks
Change in Resting Metabolic Rate (RMR)	RMR at baseline - RMR at 12 weeks measured by indirect calorimetry	Baseline and 12 weeks
Change in Daily Kilocalorie Intake	The average kilocalorie intake of 3 days was calculated each at baseline and 12 weeks. Kilocalories were calculated based on a standardized self-reported log of two weekdays and 1 weekend day.	Baseline and 12 weeks
Change in Hunger	The adolescent/young adult will report subjective hunger before each meal and snack for 24 hours using a visual analogue slider scale (0= no hunger, 100 = most hunger) and this score will be averaged over the 24 hour period.	Baseline and 12 weeks
Change in Satiety	The adolescent/young adult will report subjective satiety 30 minutes after each meal and snack for 24 hours using a visual analogue slider scale (0= no fullness, 100 = most full) and this score will be averaged over the 24 hour period.	Baseline and 12 weeks
Change in Eating in the Absence of Hunger	Validated questionnaire: Eating in the Absence of Hunger-Parent (EAH-P) completed by the parent/guardian about their adolescent/young adult. This measure has 14 items. Each item is on a 5-point Likert scale ranging from 1= "never" to 5= "always". A higher score indicates more eating in the absence of hunger. Total scores (minimum 14 to maximum 70) are calculated by taking the sum of the 14 items at each time point. The mean change in total scores by group are presented.	Baseline and 12 weeks
Change in Cognitive Restraint	The "Three-Factor Eating Questionnaire" will be completed by the adolescent/young adult. This is a 51-item questionnaire that assesses 3 eating behaviors: Cognitive Dietary Restraint, Disinhibited Eating, and Predisposition to hunger. Cognitive restraint was the domain of highest interest for this study and is reported here. Higher scores in each domain indicate more of each of those behaviors. The cognitive restraint domain score is calculated by taking the average of the 21 items in that domain. Each of the 21 items has a score of 0 or 1. MINIMUM mean score for this measure is: 0 and MAXIMUM mean score is 1. MINIMUM total score for this measure is: 0 and MAXIMUM total score is 21 (relevant to the "Full Range" in the data table below)	Baseline and 12 weeks
Change in Total Weight Related Quality of Life- Adolescent/Young Adult Report	"Impact of Weight on Quality of Life-Kids" questionnaire will be completed by the adolescents age <=19. Total and each of the 4 sub scales (Physical Comfort-6 items, Body Esteem-9 items, Social Life-6 items, and Family Relations-6 items) range from a minimum score of 0 to a maximum of 100. Higher scores indicate higher quality of life.	Baseline and 12 weeks
Change in Total Weight Related Quality of Life- Parent Reported of Adolescent/Young Adult	"Impact of Weight on Quality of Life-Kids Parent Proxy" questionnaire will be completed by the parent of the adolescent/young adult. Total and each of the 4 sub scales (Physical Comfort-6 items, Body Esteem-9 items, Social Life-6 items, and Family Relations-6 items) range from a minimum score of 0 to a maximum of 100. Higher scores indicate higher quality of life.	Baseline and 12 weeks
Change in General Health Related Quality of Life: Total Score PedsQL Instrument - Self Report	PedsQL instrument will be completed by the adolescent/young adult. The CHANGE in total scale score is reported here. The total scale score at each time point ranges from a MIN of 0 to a MAX of 100. Items are rated on a 0-4 scale. Items are reverse scored and linearly transformed to a 0-100 scale, such that 0=100, 1=75, 2=50, 3=25, and 4=0. Scale Scores are calculated as the sum of the items over the number of items answered. Higher scores indicated better health-related quality of life.	Baseline and 12 weeks
Participant Satisfaction: Questionnaire	The participating family will be asked to complete a satisfaction questionnaire that will assess reasons for participation, experience during study visits, satisfaction with the effect of the study drug, ease of communication with study staff, and study burden. The outcome presented here is the average of the parent and adolescent/young adult dyad's response to the statement: "My overall experience was positive" [1=Strongly disagree, 5=Strongly agree]	At 12 weeks

Collaborators and Investigators

• Sponsor: University of Colorado, Denver
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); University of Colorado- Clinical and Translational Sciences Institute; University of Colorado- Nutrition Obesity Research Center
• Investigators: Principal Investigator: Jaime M Moore, MD, MPH, University of Colorado School of Medicine

Study record dates

Study Major Dates

• Study Start (Actual): January 15, 2020
• Primary Completion (Actual): January 25, 2022
• Study Completion (Actual): January 25, 2022

Study Registration Dates

• First Submitted: September 17, 2019
• First Submitted That Met QC Criteria: September 18, 2019
• First Posted (Actual): September 19, 2019

Study Record Updates

• Last Update Posted (Actual): May 23, 2025
• Last Update Submitted That Met QC Criteria: May 7, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: Feasibility; Randomized Controlled Trial; Pilot; Initial Efficacy
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Obesity; Obesity, Morbid; Physiological Effects of Drugs; Molecular Mechanisms of Pharmacological Action; Hypoglycemic Agents; Autonomic Agents; Peripheral Nervous System Agents; Neurotransmitter Agents; Adrenergic Agents; Central Nervous System Stimulants; Anticonvulsants; Anti-Obesity Agents; Sympathomimetics; Appetite Depressants; Topiramate; Phentermine
• Other Study ID Numbers: 18-2793; 5P30DK048520-24 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Data obtained through this study may be provided to qualified researchers with academic interest in obesity. Data or samples shared will be coded, with no protected health information included. Approval of the request and execution of all applicable agreements (i.e. a material transfer agreement) are prerequisites to the sharing of data with the requesting party.
• IPD Sharing Time Frame: Data requests can be submitted starting 9 months after article publication and the data will be made accessible for up to 24 months. Extensions will be considered on a case-by-case basis.
• IPD Sharing Access Criteria: Access to trial IPD can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan and execution of a Data Sharing Agreement. For more information or to submit a request, please contact clinicalresearchsupportcenter@ucdenver.edu
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No