ClinicalTrials.gg
RecruitingNCT07282340PhITTUpdated Oct 7, 2026

Phentermine's Impact on Treatment in Teens

A Phase 2 interventional study of Phentermine and Placebo in Childhood Obesity, sponsored by Russell McCulloh, MD. Recruiting at 8 sites in United States. Open to participants aged 12 Years to 17 Years. Per ClinicalTrials.gov, last updated 2026-10-07.

Sponsored by Russell McCulloh, MD · Phase 2, Interventional, and Treatment

From the registry’s dates

  • Started Jun 2026; still recruiting 5 months later.
Updated Oct 7, 20262 sites addedGo to Updates ↓
Phase
Phase 2
Study type
Interventional
Enrollment
240
Allocation
Randomized
Ages
12 Years to 17 Years
Sex
All
01

Study 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. 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.

02

Conditions studied

  • Childhood Obesity

Keywords

  • Adolescent Obesity
  • Pediatric Obesity
  • Weight Loss
  • BMI Reduction
  • Phentermine
03

In context

Pediatric Obesity

1,129 studies on the registry are indexed under Pediatric Obesity; 187 are open to participants now.

This study's planned enrollment of 240 is above the median of 100 across 870 interventional studies indexed under Pediatric Obesity.

Browse Pediatric Obesity studies →

Lead sponsor

This is the only study on the registry with Russell McCulloh, MD as lead sponsor.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
12 Years to 17 Years
Sexes eligible
All
Accepts healthy volunteers
No

Eligibility criteria

Inclusion criteria* include, but are not limited to:

  • Age ≥ 12 years and \< 18 years at time of consent;
  • Tanner Staging ≥ 2 at the time of screening;
  • Obesity ( ≥ 95th age- and sex-specific CDC percentile or BMI ≥ 30 kg/m2);
  • Biological females must agree to use adequate , defined as double barrier methods, stable hormonal contraception plus single barrier method, tubal ligation, or abstinence.

Exclusion criteria* include, but are not limited to:

  • to phentermine in adults such as:

    • A history of cardiovascular disease (e.g., coronary artery disease, stroke, 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;
    • Plans to become pregnant within the study duration;
    • Known 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 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 (AST) or alanine transaminase (ALT) > 3x upper limit of age- and sex-specific normal range or renal disease ( \< 60 mL/minute); hypertriglyceridemia (triglyceride ≥ 400 mg/dL) or syndromic or monogenic obesity;
  • Any clinically significant abnormalities on a standard 12-lead at baseline;
  • Heart rate > 100 bpm at screening;
  • Current or recent use of any 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.
Terms in these criteria, in plain language(10)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

BMI (body mass index)

Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.

What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Contraindication

A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Corticosteroids (steroids)

Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.

Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.

ALT and AST (liver enzymes)

Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.

Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.

Creatinine clearance (CrCl)

How quickly the kidneys clear creatinine, a waste product, from the blood. A study may estimate it from a blood test with age, weight and sex (often by the Cockcroft–Gault formula), or measure it using blood and urine collected over a set time. Given in mL/min; higher is better.

ECG (electrocardiogram)

A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

05

Study design

Phase
Phase 2
Primary purpose
Treatment
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Quadruple (Participant, Care provider, Investigator, Outcomes assessor)
Enrollment
240 participants (estimated)

Study arms

  • Experimental
    Phentermine 16 mg Group

    Participants in this arm will receive phentermine 16 mg daily, administered as two 8 mg tablets taken orally once

    Drug: Phentermine

  • Placebo comparator
    Placebo Group

    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.

    Drug: Placebo

Interventions

  • 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.

  • DrugPlacebo

    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.

06

What researchers measure

Primary outcomes

  1. 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.

    Time frame: 52 weeks

Secondary outcomes

  1. Number of Treatment-Emergent Adverse Events (TEAEs)

    Count of TEAEs deemed probably or definitely related to study drug, including common side effects

    Time frame: 52 weeks

  2. 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

    Time frame: 52 weeks

Other outcomes

  1. Changes in Cardiometabolic Risk Factor Waist Circumference

    Change in waist circumference from baseline

    Time frame: 52 weeks

  2. Changes in Cardiometabolic Risk Factor Blood Pressure

    Change blood pressure from baseline

    Time frame: 52 weeks

  3. Changes in Cardiometabolic Risk Factor Glucose

    Change in glucose from baseline

    Time frame: 52 weeks

  4. Changes in Cardiometabolic Risk Factor Lipids

    Change in lipids from baseline

    Time frame: 52 weeks

  5. Changes in Cardiometabolic Risk Factor Hemoglobin A1C

    Change in hemoglobin A1C from baseline

    Time frame: 52 weeks

07

Study locations

8 of 8 sites recruiting
08

References and documents

Individual participant data

Plan to share: Yes — De-identified individual-level data including baseline characteristics, outcome measures and adverse events.

Supporting information: Study protocol, Statistical analysis plan, Informed consent form

No publications or documents are linked to this record.

09

Timeline

1 registry update since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Started Jun 2026 (actual). Primary completion is estimated for Jan 2028, 19 months after the start.

How these figures are worked out, and which studies are left out of them.

Registered
Dec 5, 2025
First posted
Dec 15, 2025
StartActual
Jun 3, 2026
Primary completionEst.
Jan 2028
CompletionEst.
Jan 2028
Last update
Oct 7, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Sites
2 sites added
Show 2 added (2 United States)
  • Nemours Children's Hospital · Wilmington, United States
  • Novak Center for Children's Health · Louisville, United States
Oct 7, 2026
Show all 1 update
  1. Oct 7, 2026
    2 sites added
    Show 2 added (2 United States)
    • Nemours Children's Hospital · Wilmington, United States
    • Novak Center for Children's Health · Louisville, United States
    + 2 other changes: verification date and contact details

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

10

Registry details

Key details

Study ID
NCT07282340
Lead sponsor
Russell McCulloh, MD
Collaborators
National Institutes of Health (NIH), IDeA States Pediatric Clinical Trials Network
Responsible party
Russell McCulloh, MD (Associate Vice chancellor for Clinical Research, UNMC, Heartland DCOC) — Sponsor-investigator
First posted
Dec 15, 2025
Start date
Jun 3, 2026
Primary completion
Jan 2028 (estimated)
Completion
Jan 2028 (estimated)
Last update
Oct 7, 2026

Study contacts

Aubrey VanStory
Contact
aubrey.vanstory@unmc.edu
402-559-4815
Russell McCulloh, MD
study director · UNMC

Oversight

Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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Studies of the drug tested here: Phentermine

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