Phentermine's Impact on Treatment in Teens

NCT07282340 | Not Yet Recruiting Phase 2 DMC FDA Drug

• 2 other identifiers: STUDY00161879U24OD038400
• Study Type: interventional
• Target: 240
• Locations: 0 countries
• Sites: N/A

Brief 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.

Conditions

Childhood Obesity

Keywords

Adolescent Obesity; Pediatric Obesity; Weight Loss; BMI Reduction; Phentermine

Outcome Measures

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.

  52 weeks

Secondary Outcomes (2)

• Number of Treatment-Emergent Adverse Events (TEAEs)

  52 weeks

• Number of Treatment-Emergent Adverse Events of Special Interest (TEAESIs)

  52 weeks

Other Outcomes (5)

• Changes in Cardiometabolic Risk Factor Waist Circumference

  52 weeks

• Changes in Cardiometabolic Risk Factor Blood Pressure

  52 weeks

• Changes in Cardiometabolic Risk Factor Glucose

  52 weeks

Study Arms (2)

Phentermine 16 mg Group

EXPERIMENTAL

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

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.

Drug: Placebo

Interventions

Phentermine DRUG

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.

Phentermine 16 mg Group

Placebo DRUG

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.

Placebo Group

Eligibility Criteria

• Age: 12 Years - 17 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Child (0-17)

You may qualify if:

• 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.

You may not qualify if:

• 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;

Sponsors & Collaborators

• IDeA States Pediatric Clinical Trials Network: collaborator
• Russell McCulloh, MD: lead
• National Institutes of Health (NIH): collaborator

MeSH Terms

Conditions

Pediatric Obesity; Weight Loss

Interventions

Phentermine

Condition Hierarchy (Ancestors)

Obesity; Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Body Weight Changes

Intervention Hierarchy (Ancestors)

Amphetamines; Phenethylamines; Ethylamines; Amines; Organic Chemicals

Study Officials

• Russell McCulloh, MD

  UNMC

  STUDY DIRECTOR

Central Study Contacts

Aubrey VanStory

CONTACT

402-559-4815; aubrey.vanstory@unmc.edu

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: This is a double-blind study. Participants, care providers, investigators, and outcomes assessors are blinded to treatment assignment. Only the site pharmacist is unblinded to facilitate dispensing of phentermine or placebo. Randomization is centralized and stratified by sex using a permuted block design. Blinding is maintained throughout the study unless unblinding is required for safety reasons.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: NETWORK
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Associate Vice chancellor for Clinical Research, UNMC

Model Details: 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

Study Record Dates

• First Submitted: December 5, 2025
• First Posted: December 15, 2025
• Study Start: December 1, 2025
• Primary Completion (Estimated): January 1, 2028
• Study Completion (Estimated): January 1, 2028
• Last Updated: December 15, 2025

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF