Childhood ObesityPhase 2PhITTNCT07282340
Phentermine's Impact on Treatment in Teens
A Phase 2 study testing Phentermine in people with Childhood Obesity, run by Russell McCulloh, MD at 8 sites in United States.
Trial summary
PhITT is a Phase IIb, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating the efficacy and safety of phentermine (16 mg daily) in adolescents aged 12 to <18 years with obesity. Read more about this study
- Who is it for?
- Ages 12 to 17 years
- Conditions the study is for
- Childhood Obesity
- What is being tested?
- Phentermine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 240 participants
- Where
- 8 sitesUnited States
- Study dates
- 3 Jun 2026to Jan 2028
- Phase
- Phase 2
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 12 to 17 years
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- Age ≥ 12 years and < 18 years at time of consent;
- Tanner Staging ≥ 2 at the time of screening;
- Obesity (BMI ≥ 95th age- and sex-specific CDC percentile or BMI ≥ 30 kg/m2);
- Biological females must agree to use adequate contraception, defined as double barrier methods, stable hormonal contraception plus single barrier method, tubal ligation, or abstinence.
Who cannot join
- Contraindications to phentermine in adults such as:
- A history of cardiovascular disease (e.g., coronary artery disease, stroke, clinically significant congenital heart disease, clinically significant cardiac arrhythmias, and congestive heart failure);
- History of glaucoma;
- Current or recent (within 14 days of screening) use of a monoamine oxidase (MAO) inhibitor;
- Any previous history of drug dependency or current use of an illicit substance (positive urine drug screen);
- Current pregnancy or breastfeeding;
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- Plans to become pregnant within the study duration;
- Known hypersensitivity to sympathomimetic amines;
- Current nicotine use or nicotine cessation within 3 months of screening;
- Stage 2 hypertension (or greater) or taking any medication to treat hypertension;
- Current type 1 or type 2 diabetes mellitus or taking any medication to treat diabetes or prediabetes;
- Current or recent (within 3 months of screening) use of prescribed weight loss medication(s)/medically prescribed diets (e.g., low calorie, meal replacement/herbal agents/dietary supplements or weight loss program);
- Current or recent (within 3 months of screening) use of other sympathomimetic amines such as stimulants to treat attention- deficit/hyperactive disorder;
- Use of chronic systemic glucocorticoid therapy (consecutive use of 3 months or more) or other steroid hormone therapy other than oral contraceptives;
- Use of tricyclic antidepressants, lithium, levodopa, or dopamine receptor agonists;
- History of bariatric surgery;
- History or current diagnosis of schizophrenia, psychosis, bipolar disorder, or mental illness requiring hospitalization within 12 months of screening;
- History of suicide attempt within 2 years or self-harm within 3 months of screening;
- Current Patient Health Questionnaire-9 (PHQ-9) score of ≥ 10;
- Current suicidal ideation type 4 or 5 on Columbia Suicide Severity Rating Scale (C-SSRS);
- Current Eating Attitudes Test-26 (EAT-26) score ≥ 20 or any history of anorexia or bulimia.
- Current condition or disease interfering with metabolism, such as untreated hypo- or hyperthyroidism, Cushing's syndrome;
- Current clinically significant hepatic aspartate transaminase (AST) or alanine transaminase (ALT) > 3x upper limit of age- and sex-specific normal range or renal disease (creatinine clearance < 60 mL/minute); hypertriglyceridemia (triglyceride ≥ 400 mg/dL) or syndromic or monogenic obesity;
- Any clinically significant abnormalities on a standard 12-lead electrocardiogram at baseline;
- Heart rate > 100 bpm at screening;
- Current or recent use of any investigational medication or device or participation in an interventional clinical trial within 30 days of screening;
- Any clinically significant medical or psychiatric condition or laboratory abnormality that may increase the risk associated with trial participation, investigational product administration, or interpretation of trial results.
Trial locations and contacts
8 sites in 1 country. Contact the study team or a site near you to ask about taking part.
8 sites in 1 country
United States8 sites, 8 recruiting
- Recruiting
University of New Mexico Health Sciences Center
Albuquerque, New Mexico, 87131
Arielle Padilla, RN, 505-272-1972, agartn01@salud.unm.edu
Michele Hutchison, MD
- Recruiting
Pennington Biomedical Research Center
Baton Rouge, Louisiana, 70808
Lauren Harrington, 225-763-2974, Lauren.Harrington@pbrc.edu
Goff
- Recruiting
Prisma Health-Midlands Children's Hospital
Columbia, South Carolina, 29203
Page Wiggins, 803-434-8977, mollie.wiggins@prismahealth.org
Lisa Knight, MD
- Recruiting
Children's Mercy Hospital
Kansas City, Missouri, 64108
Pete Muenks, 816-816-6840, epmuenks@cmh.edu
Helena Laroche, MD
- Recruiting
Dartmouth Hitchcock Medical Center
Lebanon, New Hampshire, 03756
Mary M McNally, 603-653-6115, Mary.M.McNally@hitchcock.org
Kimberly Dovin, MD
- Recruiting
Novak Center for Children's Health
Louisville, Kentucky, 40202
Sara Watson, MD, MS, sara.watson@louisville.edu
Ashlie Mills, ashlie.mills@louisville.edu
- Recruiting
The University of Oklahoma Health Sciences Children's Hospital
Oklahoma City, Oklahoma, 73104
Blair A Hill, 405-271-8001 ext. 34891, Blair-AppleHill@ou.edu
Gina Herbert, 405-271-3480, Gina-Herbert@ou.edu
- Recruiting
Nemours Children's Hospital
Wilmington, Delaware, 19803
Thao-Ly Phan-Vo, MD, MPH, 302-651-4730, ThaoLy.Phan@nemours.org
Charlotte Ward, MA, charlotte.ward@nemours.org
About this study
Official title: Phentermine's Impact on Treatment in Teens (PhITT): A Randomized Placebo-Controlled Trial of Phentermine for Adolescents With Obesity
PhITT is a Phase IIb, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating the efficacy and safety of phentermine (16 mg daily) in adolescents aged 12 to <18 years with obesity. Conducted across approximately 10 sites within the IDeA States Pediatric Clinical Trials Network (ISPCTN), the study aims to enroll up to 240 participants and then randomize up to 198 who meet eligibility criteria, randomized in a 2:1 ratio to phentermine or placebo over a 52-week treatment period, followed by a 2-week withdrawal assessment.
- Conditions
- Childhood Obesity
- Being tested
- Phentermine, Placebo
- Keywords
- Adolescent Obesity, Pediatric Obesity, Weight Loss, BMI Reduction, Phentermine
- Medical subject headings
- Pediatric Obesity, Weight Loss
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
PhentermineDrug
Phentermine 16 mg administered orally once daily in the morning for 52 weeks. The dose is provided as two 8 mg tablets. Participants also receive lifestyle education handouts at each study visit. The intervention is designed to evaluate the efficacy and safety of phentermine for weight loss in adolescents with obesity.
PlaceboDrug
Placebo tablets that are visually identical to phentermine tablets but contain no active pharmaceutical ingredient. Administered orally once daily in the morning for 52 weeks. Participants also receive lifestyle education handouts at each study visit. This control arm is used to evaluate the efficacy and safety of phentermine in adolescents with obesity.
| Study group | Role | What they receive |
|---|---|---|
| Phentermine 16 mg Group | Experimental | Participants in this arm will receive phentermine 16 mg daily, administered as two 8 mg tablets taken orally once Receives: Drug: Phentermine |
| Placebo Group | Placebo comparator | Participants in this arm will receive placebo tablets that are visually identical to the phentermine tablets but contain no active pharmaceutical ingredient. The placebo will be taken orally once daily in the morning for 52 weeks. All participants will also receive lifestyle education handouts at each study visit. This arm serves as the control group for evaluating the efficacy and safety of phentermine in adolescents with obesity. Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Percent Change in BMI from Baseline at Week 52
Change in body mass index (BMI) expressed as a percentage of baseline BMI at week 52.
Measured: 52 weeks
Secondary outcomes (2)
Number of Treatment-Emergent Adverse Events (TEAEs)
Count of TEAEs deemed probably or definitely related to study drug, including common side effects
Measured: 52 weeks
Number of Treatment-Emergent Adverse Events of Special Interest (TEAESIs)
Count of TEAESIs deemed probably or definitely related to study drug, including tachycardia, hypertension, depression, suicidality, and withdrawal symptoms
Measured: 52 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Dec 2025
- Study start3 Jun 2026
- Primary completionJan 2028 (estimated)
- Study completionJan 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Childhood ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants are randomly assigned in a 2:1 ratio to receive either phentermine 16 mg or placebo once daily for 52 weeks. The study uses a parallel assignment model, where each participant remains in their assigned group throughout the trial. Site-level assignment of treatments to participants will be balanced with respect to sex using a stratified permuted block of varying block size. The study is double-blinded, with participants, investigators, and study
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 240 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Russell McCulloh, MD
- Sponsor type
- Research network
- Collaborators
- National Institutes of Health (NIH), IDeA States Pediatric Clinical Trials Network
- Responsible party
- Sponsor-investigator, Russell McCulloh, MD, Heartland DCOC
- Investigators
- Russell McCulloh, MD, Study director, UNMC
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07282340
- Sponsor's protocol ID
- STUDY00161879
- Other IDs
- U24OD038400
- Acronym
- PhITT
- Status last verified
- Oct 2026
- First submitted
- 5 Dec 2025
- Last updated
- 7 Oct 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual-level data including baseline characteristics, outcome measures and adverse events.