Growth hormone helps children grow in height and supports healthy metabolism. When a child does not have enough of this hormone, their growth may be slow. This is sometimes called growth failure. Replacing growth hormone is an important part of helping these children grow over time.
Synthetic human growth hormone has a long history of use in children with growth hormone deficiency. However, until recently, treatment required daily injections.
While daily injections can be effective, they can be challenging. Many families report discomfort with frequent injections, disruptions to daily routines, and trouble staying consistent with treatment. Over time, these challenges can affect how well the treatment works.
A newer treatment option is Ngenla (somatrogon), which was approved by the FDA in 2023. This article covers how Ngenla is used to treat growth failure in children with growth hormone deficiency.
How Does Ngenla Work for Growth Failure?
Children who do not produce enough growth hormone may not reach the expected height for their age. Ngenla works in a way similar to the natural growth hormone made by the body.
Ngenla attaches to the growth hormone receptor on the surface of cells. This triggers a series of signals inside the cells that tell the body to carry out growth-related processes and control how it uses and stores energy, which affects overall growth and metabolism. Ngenla also increases the levels of another hormone called insulin-like growth factor (IGF-1). Together, growth hormone and IGF-1 can cause changes in metabolism, support growth in height, and increase the speed of growth in children with growth hormone deficiency.
How Was Ngenla Studied for Growth Failure?
To test the effectiveness of Ngenla, a clinical trial was done to compare once-weekly Ngenla (somatrogon) with once-daily somatropin in children with growth hormone deficiency.
Children who had not yet reached puberty were able to join the study if they met certain criteria. Girls had to be aged between 3 and 11, and boys had to be aged between 3 and 12. Participants also needed to have a confirmed diagnosis of growth hormone deficiency based on two separate growth hormone tests. They could not have used growth hormone treatment before, and their bone age could not be more advanced than their actual age (meaning their bones were developing at a rate expected for their age and had not matured too quickly). In addition, their height, growth rate, and IGF-1 levels had to be lower than expected for their age and sex.
Some children were not allowed to join the study because of other health conditions. This included malnutrition, certain social or environmental causes of short stature, low birth weight or size, a history of cancer, or other medical conditions that could affect growth. Children with diabetes were also excluded if they had trouble following treatment plans or if their blood sugar was not well controlled.
In total, 224 children were enrolled in the study and received treatment. Characteristics of the children who took part in the study are outlined below:
- Children ranged in age from 3 to nearly 12 years, with an average age of about 8 years.
- About 72% of children were male, and the rest were female.
- Most children were White (75%), 20% were Asian, 1% were Black or African American, and less than 1% each were American Indian/Alaska Native and Native Hawaiian/Pacific Islander. Race information was missing for about 3% of participants.
- Nearly half (49%) the participants had peak growth hormone (GH) levels between 3 and 7 nanograms per milliliter (ng/mL), about a third (32%) had peak GH levels over 7 ng/mL, and 19% had levels 3 ng/mL or less. The average peak GH level was 5.61 ng per deciliter.
- The average bone age was about 5 years.
Children were randomly assigned to receive either once-weekly Ngenla or once-daily somatropin for 12 months. As it was an open-label study, everyone involved in the study was aware of the medicine each group was using. Throughout the study, doses were adjusted according to the participants’ body weight and/or IGF-1 levels. Changes in height, weight, bones, and IGF-1 levels were measured regularly throughout the trial.
What Are the Main Benefits of Ngenla Based on Studies (Primary Outcomes)?
The main goal of the study was to evaluate whether weekly Ngenla was inferior to (any worse than) daily somatropin for increasing height velocity in children with growth hormone deficiency. Height velocity describes how fast a child is growing in height over a certain period.
Noninferiority was defined using a margin of minus 1.8 centimeters (cm) per year. This means Ngenla would be considered noninferior if children grew at a rate that was no more than 1.8 cm per year slower than with somatropin.
The two treatments were compared by measuring children’s height at the start of the study and again at months 3, 6, 9, and 12. Height results were compared with standard growth rates. Height velocity (how fast children got taller) was calculated based on height changes from the start of treatment to months 6 and 12.
Results: After 12 months of treatment, children receiving Ngenla grew an average of 10.1 cm, while those receiving somatropin grew an average of 9.78 cm. The difference in height velocity between the two treatments was 0.33 cm per year.
This means that Ngenla was not inferior to somatropin for helping children grow taller over a year. In other words, the two treatments were similarly effective.
Keep in mind that you may not see the same results in your child. Discuss treatment expectations and monitoring steps with your child’s health care provider.
How Do I Use Ngenla?
Your health care provider will show you how to give Ngenla injections. Older children may be able to self-inject the medicine after proper training and with adult supervision. Parents/guardians should give the injections to younger children. Be sure to read Instructions for Use that come with Ngenla for step-by-step directions on how to prepare and inject Ngenla.
Ngenla is a liquid solution that comes in prefilled injection pens that are meant to be used by only one person and then thrown away when empty or 28 days after the first use. Before giving the injection, look at the medicine in the pen. Do not use it if you see flakes, particles, or a change in color. Do not shake the pen because shaking can damage the medicine.
Ngenla is given as an injection under the skin (subcutaneously) once a week. You should inject it on the same day each week, at any time of the day. Injection sites include the abdomen (belly), thighs, buttocks, or upper arms. Always rotate the injection site each week. Using the same spot repeatedly can cause loss of fat under the skin, which may affect how the medicine is absorbed and how the skin looks.
What Is the Dosage of Ngenla?
The typical dosage of Ngenla is 0.66 milligrams (mg) per kilogram (kg) of body weight, given once a week. Your child’s health care provider will calculate the exact dose based on your child’s current weight and will adjust it over time depending on your child’s growth. You should not calculate the dose or change it on your own.
Ngenla is available in two strengths:
- 24 mg in 1.2 mL (20 mg/mL) that allows the dose to be adjusted in 0.2 mg steps
- 60 mg in 1.2 mL (50 mg/mL) that allows the dose to be adjusted in 0.5 mg steps
Your child’s health care provider will prescribe the dose that best fits your child’s needs. If the dose requires more than one injection, each injection should be given at a different injection site.
If you want to change the day of the week that Ngenla is given, you can do so, as long as there are at least three days between doses. After choosing a new day, you should continue giving Ngenla once weekly on that day. It may be helpful to set an alarm to remind you when the dose is due.
Note that needles are not included with Ngenla and are sold or dispensed separately. Always use a new needle for each injection. Reusing needles can make injections more painful, increase the risk of infection, may affect dose accuracy, or could even cause the needle to break off during the injection.
Is Ngenla the Same as Somatropin?
Ngenla and somatropin are similar but not exactly the same. Both are recombinant versions of human growth hormone. (Recombinant means the medicine is created in the laboratory to be identical to natural human growth hormone.) Both are given as injections under the skin. And both are effective to help support growth in children with growth hormone deficiency.
The main difference is the dosing schedule. Somatropin must be injected every day. Ngenla lasts longer in the body and is given once a week, which may make treatment easier for children and their families.
If your child is switching from daily growth hormone injections, Ngenla can typically be started the day after the last daily dose of somatropin.
Talk with your health care provider if you are interested in switching from somatropin to Ngenla.
What Can I Do to Prevent or Manage Side Effects of Ngenla?
Most children tolerate Ngenla well. But, like all growth hormone treatments, it may cause side effects in some children. Many can be prevented or managed with careful monitoring and by knowing when to contact your child’s health care provider.
Regular follow-up visits and routine lab tests help catch problems early, often before they become serious. Below are risks to be aware of and practical steps you can take to help keep your child safe:
Attend Recommended Eye Exams and Blood Tests. Before starting Ngenla, your child will need an eye exam to check for swelling behind the eyes, called papilledema. If swelling is found, your child’s health care provider will first look for the cause and treat it before starting Ngenla.
In addition, blood tests may be used to check blood sugar, thyroid function, cortisol levels, and other lab values that can change with growth hormone therapy. If your child has diabetes, prediabetes, or risk factors for diabetes, blood sugar will need closer monitoring. Medicine doses for diabetes may need to be adjusted after starting Ngenla.
Watch for Growth-Related Bone and Joint Symptoms. Rapid growth may affect bones and joints. Slipped capital femoral epiphysis is a hip problem that can happen in growing children. It occurs when the top part of the thigh bone slips out of place at the hip joint while the bone is still growing. This can cause symptoms such as hip pain, knee pain, or trouble walking.
Tell your health care provider right away if your child develops a limp or ongoing hip or knee pain. If your child has scoliosis, spine checks are important because rapid growth can cause curves to worsen.
Fluid Retention Can Be a Temporary Side Effect. Fluid retention means the body is holding on to extra fluid. During treatment with Ngenla, some children may notice swelling, most often in the hands, feet, or face. This can sometimes put pressure on nearby nerves and cause symptoms such as tingling, numbness, or discomfort, especially in the hands or wrists.
These symptoms are usually temporary and are more likely to happen at higher doses. Let your child’s health care provider know if you notice swelling or your child complains of pain or tingling. The symptoms may improve on their own as the body adjusts to treatment, or the dose may need to be adjusted.
To help manage fluid retention, encourage your child to stay active and avoid excessively salty foods that can make swelling worse. Do not change the dose or stop treatment without talking to your health care provider.
Injection Site Reactions. The most common side effect of Ngenla is injection site reactions, such as pain, swelling, redness, itching, or bleeding. In studies, these reactions affected 42% of children using Ngenla. In comparison, 25% of children using daily somatropin experienced injection site reactions. As mentioned earlier, it’s important to rotate the injection site each week. Injection site reactions usually go away on their own, but here are simple ways to help manage bothersome discomfort:
- For pain or swelling: Ask your health care provider if it’s okay to apply a cool compress to the injection site to help reduce discomfort. They can also suggest an over-the-counter pain reliever that is safe for your child.
- For bleeding: If bleeding occurs, apply gentle pressure to the area until it stops. Once it stops, you can cover the area with a small bandage.
This is not a complete list of Ngenla side effects. Tell your health care provider if side effects feel severe, worsen, or do not improve.
Is There Any Cost Assistance Available?
A cost assistance program is available from Pfizer, the maker of Ngenla. It may reduce the amount you pay. Whether you qualify to enroll may depend on what type of insurance you have or if you are uninsured. Visit this website to see if you’re eligible for copay savings. You can also call 800-645-1280 to speak with a representative about financial support options.