Atomoxetine in Melanocortin Obesity Syndrome

Recruiting now · Phase 2 · Has a placebo group

Conditions studied: Melanocortin Obesity Syndrome, MCOS

In brief

This is a phase 2 randomized placebo-controlled crossover trial to determine the safety and efficacy of atomoxetine for treating obesity caused by loss-of-function variants in the melanocortin-4 receptor (MC4R), the most common cause of genetic obesity disorders. Atomoxetine was selected for this pilot trial because it has been shown to increase brain-derived neurotrophic factor (BDNF) within the central nervous system and in peripheral circulation. Targeting BDNF is a specific strategy for treating MC4R abnormalities because BDNF functions as a downstream mediator of MC4R signaling.

Key facts

Study ID

NCT06899178

Run by

Icahn School of Medicine at Mount Sinai

People needed

20

Starts

2026-09-01

Expected to finish

2028-06-01

Last updated by the study team

2026-08-07

Who can join

Age: 6 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Age 6 years and above
• Documented MC4R variant classified as pathogenic, likely pathogenic, or variant of uncertain significance per ACMG criteria. If testing was done in a research lab, it will be confirmed by a CLIA-approved lab prior to randomization.
• Obesity defined as BMI ≥30 kg/m2 in adults or ≥95th percentile for age and sex in children

You may not qualify if…

• Use of atomoxetine, viloxazine (another selective norepinephrine-reuptake inhibitor), methylphenidate, amphetamine, dextroamphetamine, lisdexamfetamine, phentermine, or any other stimulant medication in the past 30 days. If on other ADHD medications, such as guanfacine and clonidine, must be on a stable dose for >3 months.
• Weight loss >5% in the past 3 months.
• Initiation of new weight loss program, including diet or medications. If on weight loss medications, must be on a stable dose for >3 months.
• Inability to swallow capsules.
• History of hypersensitivity to atomoxetine.
• Narrow angle glaucoma.
• History of pheochromocytoma.
• Uncontrolled Stage 2 hypertension (≥95th percentile + 12 mmHg or >140/90, whichever is lower) at screening. If on antihypertensive medication, must be on stable dose for >3 months.
• Hepatic insufficiency including cirrhosis and acute hepatitis (AST or ALT >3x upper limit of normal)
• Uncontrolled asthma requiring albuterol more than once weekly over the past 3 months
• History of a cardiac arrhythmia (not including bradycardia)
• Current use of monoamine oxidase inhibitors
• Pregnancy or intention to become pregnant during the next year
• History of Major Depressive Disorder in the past 2 years, lifetime history of suicide attempt, history of any suicidal behavior in the past month, history of other severe psychiatric disorders (e.g. schizophrenia, bipolar disorder)
• PHQ-9 score is ≥15 or suicidal ideation of type 4 or 5 (C-SSR) in the past month
• Unable to comply with study procedures in the opinion of the investigator

Where it is running

• Mount Sinai Hospital — New York, New York, United States (enrolling)
• Nationwide Children's Hospital — Columbus, Ohio, United States
• Vanderbilt University Medical Center — Nashville, Tennessee, United States

Full record on ClinicalTrials.gov

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