NCT05176626

Long-term Effectiveness of the Antiobesity Medication Phentermine

• Status: Active Not Recruiting
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 870 (actual)
• Sponsor: Wake Forest University Health Sciences · Academic / Other
• Sex: All
• Age: 18 Years – 70 Years
• Healthy volunteers: Not accepted

Summary

The purpose of this research study is to understand the long-term effects of the drug phentermine on weight, blood pressure, other health outcomes, and safety. Phentermine has been approved by the US Food and Drug Administration (FDA) for weight management since 1959, but it has not been approved for long-term use (i.e., treatment lasting more than 12 weeks). This trial is designed to learn about the long-term effects of phentermine for up to 2 years because obesity is a chronic disease and expert guidelines recommend long-term use of anti-obesity medications as one treatment option.

Detailed description

The Long-term Effectiveness of the Anti-obesity medication Phentermine (LEAP) trial, a placebo-controlled, randomized trial, will be conducted at 5 clinical sites across the United States. All participants will be provided with an evidence-based online lifestyle intervention, and participants receiving 24 mg/day of phentermine vs. a placebo for up to 24 months will be compared in an intent-to-treat fashion. The co-primary outcomes of percent weight loss and change in systolic blood pressure at 24 months will be examined. Also, between group changes in drivers of energy balance, including resting metabolic rate, caloric intake, physical activity and dietary composition will be compared. To explore the effects of weight loss on cardiometabolic health, changes in heart rate, hemoglobin A1c, lipids, waist circumference, atherosclerotic cardiovascular disease (ASCVD) risk score, and novel ECG markers of cardiac strain will be compared. Overall adverse event and serious adverse event rate, including rates of incident cardiovascular disease or death, will be measured.

Conditions

• Obesity
• Obesity; Drug
• Lifestyle, Healthy

Interventions

Type	Name	Description
BEHAVIORAL	Online Lifestyle Behavioral Therapy	Participants will receive access to the WW™ digital application for the duration of their participation. The WW™ digital application can be accessed using a smartphone, tablet or personal computer and includes functions such as food journaling, progress charts, lifestyle coaching , ability to manually enter exercise data or link with a fitness tracking device, incentives for behavior change, recipes, and local restaurant recommendations using GPS. Over the course of 12 clinic visits with an obesity provider, participants will be prescribed a dietary plan based on the WW™ app and will be asked to journal dietary intake.
DRUG	Phentermine Hydrochloride 8 MG	At the randomization visit, participants will be started on 8 mg PO daily of phentermine or placebo, with a recommendation to take the medication in the morning. They will be provided with detailed instructions on how to increase their dose of study drug over the subsequent weeks. After one week, participants will increase to 16 mg daily. After the second week, participants will further increase their dose to 24 mg daily and at the 1-month in-person follow-up, participants who tolerate the 24 mg dose will be maintained on this as the maximum daily dose for a total of 24 months. For participants who do not tolerate an escalation in medication dose due to side effects, adverse events, and/or elevations in blood pressure and/or heart rate, the study clinician may adjust the dose and/or delay dose escalation. Study clinicians will work with participants to achieve and sustain the maximum dose tolerated.

Timeline

• Start date: 2022-06-30
• Primary completion: 2026-12-31
• Completion: 2026-12-31
• First posted: 2022-01-04
• Last updated: 2026-03-31

Locations

4 sites across 1 country: United States

Regulatory

• FDA-regulated drug study