Skytrofa (lonapegsomatropin-tcgd) is a prescription drug that’s used to treat growth hormone deficiency (GHD) in certain children. It’s given by injection under the skin once weekly.

Skytrofa is a growth hormone medication. It’s used for children who aren’t growing as expected because their body doesn’t make enough growth hormone. Specifically, Skytrofa is approved for use in children ages 1 year and older who weigh at least 11.5 kilograms (kg). For reference, 1 kg is about 2.2 pounds (lb), so this is about 25 lb.

To learn more about Skytrofa’s uses, see the “What is Skytrofa used for?” section.

Skytrofa basics

Skytrofa contains the active ingredient lonapegsomatropin-tcgd.

Skytrofa is a biologic medication. A biologic is made from parts of living organisms. It’s available only as a brand-name drug and not in a generic or biosimilar form.

Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.

Biosimilars will have the same active ingredient core name as the brand-name drug. But they’ll have unique suffixes. This is why “-tcgd” appears at the end of the name of the active ingredient. This is to show that it’s distinct from biosimilars that may be created in the future.

Find answers to some commonly asked questions about Skytrofa.

How does Skytrofa compare with Norditropin?

Both Skytrofa and Norditropin (somatropin) are used to treat GHD in children. They belong to the same group of drugs (growth hormones) and work the same way to treat GHD.

The main difference between Skytrofa and Norditropin is how often you inject them. Norditropin injections are given every day or 6 days weekly. Skytrofa injections use a dosing schedule of 1 day weekly.

Skytrofa is a brand-name medication. Because of this, it may be more expensive than Norditropin. Norditropin is available in generic or biosimilar versions.

If your child is using Skytrofa and you’re interested in Norditropin, talk with your child’s doctor.

How does Skytrofa compare with Sogroya?

Skytrofa and Sogroya (somapacitan-beco) are similar medications. Both are growth hormone medications used to treat GHD in children. In addition, Sogroya is used to treat GHD in adults. (Skytrofa is not approved for use in adults.)

Skytrofa and Sogroya have the same dose frequency. Doses are once weekly as injections under the skin, but their forms are slightly different. Sogroya comes as a liquid solution in a prefilled pen. Skytrofa comes as a powder in cartridges that you load into an auto-injector device. It automatically mixes the powder with sterile water, and then you use it to inject the dose of Skytrofa.

Talk with your child’s doctor or pharmacist to learn more about how Skytrofa and other growth hormone medications compare.

Skytrofa is used to treat GHD in certain children. Specifically, Skytrofa is approved for use in children ages 1 year and older who weigh at least 11.5 kg, which is about 25 lb.

Growth hormone regulates the growth and development of your child’s body. Children with GHD grow less than expected because their bodies don’t make enough of this hormone. Without treatment, children with GHD may have short stature, delayed puberty, and other complications.

Skytrofa is a lab-made version of human growth hormone. It works by acting just like natural growth hormone and stimulates bone growth.

Like most drugs, Skytrofa may cause mild to serious side effects. The lists below describe some of the more common side effects that Skytrofa may cause. These lists don’t include all side effects possible.

Keep in mind that side effects of a drug can depend on:

  • your child’s age
  • other health conditions your child has
  • other medications your child takes

Your child’s doctor or pharmacist can tell you more about the potential side effects of Skytrofa. They also can suggest ways to help reduce side effects.

Mild side effects

Here’s a list of some of the mild side effects that Skytrofa can cause. To learn about other mild side effects, talk with your child’s doctor or pharmacist or read Skytrofa’s prescribing information.

Mild side effects of Skytrofa that have been reported include:

  • viral infection, such as the common cold
  • fever
  • cough
  • nausea and vomiting
  • diarrhea
  • pain in the abdomen
  • bruises or petechiae (small spots on the skin due to bleeding under the skin)
  • nosebleed
  • swollen or painful joints

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your child’s doctor or pharmacist.

Serious side effects

Serious side effects from Skytrofa can occur, but they aren’t common. If your child has serious side effects from Skytrofa, call their doctor right away. But if you think they’re having a medical emergency, you should call 911. Or call your local emergency number.

Serious side effects of Skytrofa that have been reported include:

  • high pressure and swelling in the brain
  • inflammation of the pancreas
  • serious bone problems, including:
Allergic reaction

For some people, Skytrofa can cause an allergic reaction. Allergic reactions weren’t reported during Skytrofa’s studies. But severe allergic reactions have occurred since the drug’s approval.

In general, symptoms of allergic reaction can be mild or serious.

What might help

If your child has mild symptoms of an allergic reaction, such as a mild rash, call their doctor right away. They may suggest a treatment to manage the symptoms. They can also determine whether your child should keep using Skytrofa.

If your child has symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911. Or call your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

Your child’s doctor can confirm whether your child has had a serious allergic reaction to Skytrofa. If so, they may have your child switch to a different treatment.

Your child’s doctor will recommend the dosage of Skytrofa that’s right for your child. Below are commonly used dosages, but always use the dosage your child’s doctor prescribes.

Form and strengths

Skytrofa comes as a powder in single-dose cartridges. A cartridge gets loaded into the Skytrofa auto-injector, which makes a liquid solution. You use the auto-injector to administer each dose as an injection under the skin.

Skytrofa is available in nine strengths:

  • 3 milligrams (mg)
  • 3.6 mg
  • 4.3 mg
  • 5.2 mg
  • 6.3 mg
  • 7.6 mg
  • 9.1 mg
  • 11 mg
  • 13.3 mg

Recommended dosage

Skytrofa’s dosage is based on your child’s body weight. Their doctor may calculate the dose or use the dosing chart provided in Skytrofa’s prescribing information. They will monitor your child’s growth and how well they tolerate the medication. If needed, they may adjust the dose over time.

The recommended dose of Skytrofa is 0.24 mg per kg of body weight (mg/kg). This dose is given once weekly.

As a dosage example, if a child weighs 15 kg (about 33 lb), their recommended dosage of Skytrofa would be 3.6 mg once weekly.

How to use

Your child’s doctor or another healthcare professional will show you how to give your child Skytrofa injections at home. Be sure to follow the doctor’s instructions.

You give Skytrofa by injection under the skin using an auto-injector. You’ll inject the drug into your child’s abdomen, buttock, or thigh.

The drugmaker’s website also has instructions and videos on how to use Skytrofa.

Questions about using Skytrofa

Below are some common questions about using Skytrofa.

  • Should your child use Skytrofa with food? Skytrofa can be injected at any time of day, with or without food.
  • Is there a best time of day to inject Skytrofa? Skytrofa can be injected at any time of day, as long as you use it on the same day of each week. This helps keep a consistent level of the drug in your child’s body, which helps Skytrofa work effectively.
  • What if you miss a dose of Skytrofa? If you miss a dose of Skytrofa, inject it as soon as possible. But if the missed dose is more than 2 days late, skip the missed dose. Then inject the regular dose on the next scheduled day. Doses of Skytrofa should be at least 5 days apart. You should not inject extra doses at once to make up for a missed dose. Doing so could raise your child’s risk of side effects.
  • Will your child need to use Skytrofa long term? Skytrofa is typically used as a long-term treatment while your child is still actively growing. Your child’s doctor will recommend when to stop Skytrofa, which is usually once your child is no longer growing taller. For information about long-term overdosage, refer to the “Overdose” section below.
  • How long does Skytrofa take to work? Skytrofa begins to work after the first dose. But you and your child may not notice the drug working for several months. Your child’s doctor will monitor your child’s height and growth rates throughout Skytrofa treatment. This helps them see whether the drug is working as expected.

Overdose

Do not use more Skytrofa than prescribed, as this can lead to harmful effects.

Symptoms of overdose

Symptoms caused by an overdose can result in immediate effects such as:

It’s important to know that long-term overdosage of growth hormone, such as Skytrofa, may cause gigantism. This condition involves excessive body growth.

What to do in case you use too much Skytrofa

Call your child’s doctor if you think they’ve used too much Skytrofa. You can also call 800-222-1222 to reach America’s Poison Centers or use its online resource. But if your child has severe symptoms, immediately call 911 or your local emergency number. Or go to the nearest emergency room.

Below is important information you should consider before using Skytrofa.

Interactions

Taking a drug with certain medications, vaccines, foods, and other things can affect how the drug works. These effects are called interactions.

Skytrofa can interact with several other medications.

Before starting Skytrofa treatment, talk with your child’s doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs your child takes. Also, tell them about any vitamins, herbs, and supplements your child takes. Sharing this information can help you avoid potential interactions.

Drug interactions

Below is a list of medications that can interact with Skytrofa. This list does not contain all drugs that may interact with Skytrofa. If you have questions about drug interactions that may affect your child, ask your child’s doctor or pharmacist.

Drug group or drug nameDrug examples
diabetes medications • insulin, such as insulin lispro (Humalog)
• metformin (Glumetza, Riomet, others)
oral estrogen medications • estradiol (Estrace)
• conjugated estrogens (Premarin)
corticosteroids • prednisone
• cortisone
numerous medications that get processed by certain liver enzymes• acetaminophen (Tylenol)
• dextromethorphan (Delsym)
• montelukast (Singulair)

Skytrofa and alcohol

Alcohol is not known to interact with Skytrofa.

Pregnancy and breastfeeding

It’s not known whether it’s safe to use Skytrofa during pregnancy or while breastfeeding. If pregnancy might be possible, talk with your child’s doctor before starting Skytrofa treatment.

Warnings

Skytrofa can sometimes cause harmful effects in people who have certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Skytrofa is a good treatment option for your child.

Talk with your child’s doctor about your child’s health history before they start Skytrofa. Be sure to tell them if any of the following factors apply to your child:

Whether or not you have health insurance, cost may be a factor when you’re considering Skytrofa. What you’ll pay for Skytrofa may depend on several things, such as your treatment plan and the pharmacy you use.

Here are a few things to consider regarding cost:

  • Cost information and savings coupons: You can visit Optum Perks to get price estimates of what you’d pay for some medications when using coupons from the site. (Note: Optum Perks coupons cannot be used with any insurance copays or benefits.)
  • Savings program: If you have questions about how to pay for your prescription, talk with your child’s doctor or pharmacist. The Ascendis Signature Access Program also may be available to assist you.

You can also check out this article to learn more about saving money on prescriptions.

Other drugs are available that can treat your child’s condition. If you’d like to explore an alternative to Skytrofa, talk with your child’s doctor. They can tell you about other medications that might work for your child.

The following drugs are similar to Skytrofa:

  • somatropin (Norditropin)
  • somapacitan-beco (Sogroya)
  • somatrogon-ghla (Ngenla)

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.