Ins and Outs of Using Obesity Meds in Pediatric Patients

ORLANDO, Fla. — The rationale for using obesity medications in pediatric patients is that it’s using “a biological intervention to treat a biologically based disease,” according to Claudia Fox, MD, MPH, an associate professor of pediatrics and co-director of the Center for Pediatric Obesity Medicine at the University of Minnesota, Minneapolis. At the American Academy of Pediatrics (AAP) 2024 National Conference, Fox provided an overview of what obesity medications are approved for in youth and how to determine which medications may be best for different patients.

“This field is changing so rapidly that even over the course of the last 3 or 4 months, the verbiage around what we should be calling these interventions has changed,” Fox noted. Instead of “anti-obesity” medications, “most of us are now using the term obesity medications to highlight or to reduce chances of stigma and bias that can come along with this topic.”

Jessica Ivers, MD, a pediatrician at Swedish Pediatrics in Seattle, said she found the session very informative, particularly because she doesn’t think many pediatricians currently feel very comfortable prescribing obesity medications.

“It answered questions that any general pediatrician would have, and it’s kind of a new field that people are learning about,” Ivers said. “I think we just need more education. It’s just too new, and people haven’t had the education and the support from colleagues to [use the medications].”

Fox first reminded attendees of precisely what obesity is: A chronic, relapsing, multifactorial, neurobehavioral disease that involves the accumulation and/or distribution of excess body fat that results in impaired health. AAP clinical practice guidelines currently advise that youth aged 12 years or older who have obesity be offered weight loss pharmacotherapy as an adjunct to lifestyle treatment, taking into consideration the indications, risks, and benefits of each medication.

That doesn’t necessarily mean every child aged 12 years or older with a body mass index (BMI) of at least the 95th percentile should be prescribed one of these medications, Fox said. But pediatricians should start becoming familiar with the options and recognize that part of reducing the stigma of this disease is emphasizing that these medications are prescribed not for “weight loss” but to treat the disease of obesity, Fox said. The guidelines advise “early, intensive care” and focusing on the whole child, “using a family-centered and non-stigmatizing approach that acknowledges obesity’s biologic, social, and structural drivers.”

Offer the Full Spectrum of Care Early On

Early intervention means starting obesity treatment at diagnosis, without watchful waiting or the previously recommended staged approach. Instead of trying lifestyle therapy for 3-6 months, then considering the addition of medication, and then considering bariatric surgery, “we should be offering the full spectrum of obesity care as appropriate for that individual patient,” Fox said.

Some children with severe obesity may need the combination of lifestyle therapy and pharmacotherapy right up front, whereas another might be able to try lifestyle therapy alone for a while first. “What we know is that for most interventions, whether it is lifestyle therapy, a medication, or bariatric surgery, early response typically predicts longer-term response,” Fox said. A study conducted by her group, for example, found that a 3% BMI reduction after 1 month with lifestyle therapy was very predictive of clinically meaningful BMI reduction at 1 year.

As with any medical treatment, physicians need to weigh the risks of the medication — short-term side effects and unknown long-term risks (or benefits) — against the risks of not treating. Because obesity is a progressive disease, “if we don’t treat it, most will develop comorbid conditions, or worsening of their already present comorbid conditions, and this does indeed lead to shortened life expectancy,” Fox said. Those who should be treated with medication are obviously those in whom the benefits outweigh the risks, Fox said, which depends on their age, their comorbidities, the severity of obesity, and the safety and efficacy of medication options.

“If I have a patient who has maybe class 2 obesity but no other comorbid conditions, I may be less inclined to start an obesity medication than a kid who has class 1 obesity and obstructive sleep apnea, for instance,” Fox said. “Some of the medications are very, very potent and effective. If you have a kid who maybe has less severe forms of obesity, perhaps they don’t need something that’s so potent.”

BMI trajectory is also a factor to consider. She said she may not be too concerned about a 16-year-old who has always been at the 95th percentile and is otherwise healthy, but the situation is different for a 16-year-old who used to be in the 25th percentile and has rapidly progressed to the 50th and then 75th percentiles in a trajectory heading straight up.

Another factor that may come into play is the patient and family preferences, though Fox noted that weight bias and stigma often interfere here. If obesity medications are brought up, the family may bring up the need for more exercise and better meal prep at home.

“They have this sense that they just need to try harder, that if they did that, the obesity would somehow get better on its own,” Fox said. “That’s an internalized bias that it’s somehow their fault, rather than realizing that this is indeed a biological disorder.”

Finally, clinicians may want to consider the child’s response to lifestyle therapy and whether they have already had bariatric surgery because these medications can be prescribed in people who did not have an adequate response to surgery.

Overview of the Medications

There are currently six obesity medications approved by the US Food and Drug Administration (FDA) for use in youth: Phentermine, orlistat, liraglutide, phentermine/topiramate, semaglutide, and setmelanotide.

Of these, orlistat is rarely used now because it results in the least amount of change in BMI (about a 3% loss change in BMI), has a lot of gastrointestinal side effects, often is not covered by insurance, and is expensive out of pocket. Setmelanotide is indicated only in those aged 6 years or older who have obesity due to Bardet-Biedl syndrome or one of three other rare genetic conditions: A POMC, LEPR, or PCSK1 deficiency. Fox therefore focused on the other medications besides these two.

While nearly all the currently available obesity medications are only approved in those aged 12 years or older, Fox noted that studies are ongoing at younger ages, so some of these medications may receive approval in younger populations in the future. The only one currently available for a younger age is liraglutide, which is approved down to 6 years old in children with type 2 diabetes.

“Very young kids who have very severe forms of obesity need intervention, and unfortunately, at this point, we really don’t have much to offer them,” Fox said.

Fox highlighted six key factors to consider in selecting a medication for those aged 12 years or older, though one of these, in the US healthcare system, can tend to trump all the others. Those factors are mechanism of action, side effect profile, effects on other diagnoses, patient/family preferences, provider comfort, and finally — the potentially overruling one — insurance coverage and access.

“These days, insurance coverage and access are really the number-one driver when I’m seeing a patient,” Fox said. “The first thing I do is look at their insurance and then also look at what kind of updates our pharmacist has given us about which medication is currently in stock.”

Each medication has different properties that should be considered with the child’s health profile. For example, topiramate is a carbonic anhydrase inhibitor so likely shouldn’t be prescribed in a child who is taking any other carbonic anhydrase inhibitor. Fox said she probably wouldn’t prescribe phentermine in a child with severe anxiety because it might enhance the anxiety effect. But if a child has migraines, she may be more inclined to try phentermine/topiramate first because the topiramate may help with the migraines. Similarly, if a child has type 2 diabetes or prediabetes, she may lean toward one of the glucagon-like peptide 1 (GLP-1) agonist drugs.

Liraglutide and Semaglutide

Liraglutide and semaglutide are both GLP-1 receptor agonists administered subcutaneously to reduce appetite, increase satiety, slow gastric emptying, and reduce the food reward response in the brain. Liraglutide can result in up to 4.5%-5% change in BMI, and semaglutide, the most potent of all the medications, can result in up to a 17% change in BMI.

Liraglutide and semaglutide are both approved for patients aged 12 years or older who weigh at least 60 kg and have a BMI of at least the 95th percentile. Liraglutide is also approved for those aged 10 years or older with type 2 diabetes. Both are contraindicated in those with a family history of medullary thyroid cancer or multiple endocrine neoplasia II. The risks to watch for include pancreatitis and gallbladder disease. Also keep in mind if you have a patient with type 1 diabetes and insulin resistance, prescribing a GLP-1 agonist is appropriate, but their insulin needs will decrease, necessitating close monitoring of their blood glucose, Fox noted.

These GLP-1 medications can be considered for those who have insurance coverage for them, who have diabetes or prediabetes, who are comfortable with daily (liraglutide) or weekly (semaglutide) injections, who have food cravings, and who have poor satiety or satiation. Without insurance, these medications are very expensive.

The most common side effects include injection site reactions and nausea, vomiting, and diarrhea, though all these usually fade and can be minimized with small portions and slower eating if needed. Less common possible side effects can include abdominal pain, constipation, headache, dizziness, fatigue, and hypoglycemia. If patients develop severe belly pain that radiates to their back, they should be assessed for pancreatitis.

It’s also important to demonstrate for patients how to do the injections, Fox said. Liraglutide dosing begins at 0.6 mg daily for a week, followed by a week at 1.2 mg, a week at 1.8 mg, a week at 2.4 mg, and then 3 mg daily. Semaglutide dosing starts at 0.25 mg weekly for 4 weeks, then going up each subsequent month as needed to 0.5 mg, then 1 mg, then 1.7 mg, and finally 2.4 mg. Though there’s no standard follow-up schedule for these medications, Fox suggested considering monthly visits for the first 3 months and then every 2-3 months to assess heart rate and blood pressure, the injection site, adherence, side effects, and the effect on BMI and eating.

“Are they getting appetite suppression, but not too much appetite suppression?” Fox said. “Just like in eating disorder treatment, we want our patients to eat regularly spaced meals. If their appetite is so suppressed that they are hardly eating anything, that’s a problem.”

Fox also offered the following additional pearls about these medications:

• Though manufacturers have struggled to keep up with demand, the shortages of these medications are improving. However, beware the compounding pharmacies filling the gap because compounded medications are not FDA-approved, and quality control issues are a concern.
• Prior authorizations are usually needed, and common reasons for denial to anticipate include lack of documentation on not having contraindications, the patient not following a low-calorie diet or engaging in physical activity, and the patient not having seen a registered dietitian.
• Patients should expect gastrointestinal side effects, but ondansetron can be prescribed to lessen the intensity.

Phentermine/Topiramate

Phentermine/topiramate extended-release is a once daily oral tablet, with the phentermine acting to reduce appetite (by simulating the release of norepinephrine) and the topiramate reducing caloric intake and food reward response (by increasing gamma-aminobutyric acid activity). It’s approved for those aged 12 years or older with a BMI of at least the 95th percentile and should be considered in those with strong hunger, low energy, binge eating disorder, or migraines, as well as those who have insurance coverage for it. It can result in up to a 10% change in BMI.

Contraindications include pregnancy, substance use, cardiovascular disease (though it’s okay in patients with controlled hypertension), hyperthyroidism, glaucoma, and monoamine oxidase inhibitor (MAOI) use. Fox emphasized the teratogenic effects, so patients capable of pregnancy need to be on reliable birth control. The most common side effects include paresthesia, dizziness, dysgeusia, insomnia, and constipation.

A risk of topiramate is kidney stones, so patients should drink a lot of water, especially in hot weather, Fox said. Other risks can include metabolic acidosis, suicidality, poor cognitive function, high blood pressure, and renal impairment.

“If your patient is struggling academically, I might use this medication a bit more cautiously, particularly when the dose gets above 100 mg a day,” Fox said. “That’s when the cognitive effects tend to emerge more strongly.”

Patients with congenital heart disease should meet with their cardiologist before starting this medication, and although patients taking selective serotonin reuptake inhibitors (SSRIs) can take this, there is a potential increased risk for serotonin syndrome because phentermine has a little bit of serotonergic activity, she said.

Before prescribing, do an exam to ensure the patient doesn’t have a heart murmur, isn’t hypertensive, isn’t pregnant, has normal kidney function, and has bicarbonate in a reasonable range. Dosing begins with a daily 3.75/23-mg capsule for 2 weeks, followed by 2 weeks at 7.5 mg/46 mg. As with the GLP-1 drugs, Fox advises considering monthly follow-ups for the first 3 months and then visits every 2-3 months. Each visit should include the assessment of cardiovascular health, heart rate, blood pressure, side effects, pregnancy risk, and the medication’s effect on BMI and eating. If the patient is tolerating a dose of 7.5 mg/46 mg, it can be increased to 11.25 mg/69 mg for 2 weeks and then to 15 mg/92 mg. Bicarbonate and creatinine should be checked every 6-12 months; if bicarbonate

Fox noted that this drug is expected to go off patent in late 2024 or in 2025, which will substantially reduce the cost. It’s also possible to prescribe phentermine and topiramate separately, which may reduce costs or help with insurance coverage and can allow for evening dosing of topiramate.

Phentermine

Phentermine alone is only approved for those older than 16 years who have a BMI of at least 30, or at least 27 with weight-related comorbidities, and it’s not approved for use longer than 12 weeks. It results in a BMI change of up to 5%. It should be considered in those with strong hunger and low energy and in those who don’t have adequate insurance coverage because out-of-pocket costs can be as little as $5/mo.

Contraindications are the same as those for the combined pill above: Substance use, cardiovascular disease, hyperthyroidism, glaucoma, MAOI use, and agitation. Again, take caution with patients who have hypertension, have congenital heart disease, or take SSRIs or insulin.

Side effects can include palpitations, tachycardia, dry mouth, headache, insomnia, and anxiety. The dose starts at 15 mg daily, and Fox advises following a similar follow-up as with the other medications, at which clinicians should assess BMI, the medication’s effect on eating, cardiovascular health, and side effects and have a discussion about off-label use. Off-label use refers to prescriptions lasting longer than 12 weeks, but it’s arguably safer than attention-deficit/hyperactivity disorder stimulants because of the lower addiction potential, Fox said.

What Else to Know

Because obesity is a chronic disease, treatment will be ongoing, Fox noted. A lot of people will ask when or where the “off-ramp” for these medications is, but many people will need these medications long term just as someone with other chronic diseases requires lifetime pharmacotherapy. The treatment intensity will vary based on disease severity and individual characteristics, Fox said.

For those feeling overwhelmed by the options, Fox advises clinicians to start by picking one medication to learn and then spending the time to read the FDA package insert in full. Get samples and then closely follow patients to learn that medication well before moving on to learn another. She also noted the opportunity for pediatricians to see a pediatric obesity medicine fellowship.

No external funding was used for the presentation. Fox is a site principal investigator for clinical trials sponsored by Novo Nordisk and Eli Lilly. Ivers had no disclosures.

Tara Haelle is a Dallas-based science journalist.