NCT07282340 · Russell McCulloh, MD
Phentermine's Impact on Treatment in Teens
(PhITT)
What this study is about
PhITT is a Phase IIb, conducted at multiple hospitals, randomly assigned, where neither patients nor doctors know which treatment is given, compared against an inactive treatment clinical trial evaluating the effectiveness and safety of phentermine (16 mg daily) in adolescents aged 12 to \<18 years with obesity.
View original scientific description
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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 (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.
Exclusion criteria
- include, but are not limited to:
- 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;
- 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.
Where
- Albuquerque, New Mexico
- Columbia, South Carolina
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 16, 2026 · Source of record for eligibility and locations