Ngenla (Somatrogon)
Long-acting growth hormone for once-weekly subcutaneous injection
Ngenla (somatrogon) is a long-acting growth hormone administered as a once-weekly subcutaneous injection for children and adolescents aged 3 years and older with growth hormone deficiency. Unlike traditional daily growth hormone injections, Ngenla requires only one injection per week, significantly reducing the treatment burden for patients and families. It is manufactured by Pfizer and was approved by the European Medicines Agency (EMA) in 2022.
Quick Facts
Key Takeaways
- Ngenla is a once-weekly growth hormone injection, replacing the need for daily shots in children with growth hormone deficiency.
- The recommended dose is 0.66 mg per kg body weight, given on the same day each week using a prefilled injection pen.
- The most common side effects are headache, injection site reactions, and fever, which typically resolve on their own.
- Store refrigerated (2–8°C) and use within 28 days after first use. Do not freeze.
- Regular monitoring of thyroid function, blood sugar levels, and growth progress is essential during treatment.
What Is Ngenla and What Is It Used For?
Quick Answer: Ngenla contains somatrogon, a modified form of human growth hormone given as a once-weekly injection to children and adolescents (aged 3+) who do not produce enough growth hormone on their own and are not growing at a normal rate.
Ngenla (somatrogon) belongs to the class of growth hormone medicines used in pediatric endocrinology. The active substance, somatrogon, is a modified form of naturally occurring human growth hormone (hGH). Natural growth hormone is essential for the growth and development of bones and muscles, and it plays a critical role in regulating body composition, including the proper balance of fat and muscle tissue.
Growth hormone deficiency (GHD) is a condition in which the pituitary gland does not produce adequate amounts of growth hormone. This can lead to significantly slower growth in children compared to their peers. Without treatment, children with GHD may not reach their expected adult height. GHD affects approximately 1 in 4,000 to 1 in 10,000 children worldwide, according to estimates from the Endocrine Society.
Somatrogon is manufactured using recombinant DNA technology. This means it is produced in cells that have been genetically modified in a laboratory to synthesize the growth hormone analogue. The key structural modification in somatrogon is the fusion of human growth hormone with the C-terminal peptide (CTP) of human chorionic gonadotropin (hCG). This modification extends the half-life of the molecule, allowing it to be administered once weekly rather than daily, which represents a significant advancement in growth hormone therapy.
Clinical trials, including the pivotal phase 3 study (the global OPD study), demonstrated that Ngenla administered once weekly achieved comparable growth rates to daily somatropin injections in treatment-naive children with GHD. The annualized height velocity at 12 months was statistically non-inferior to daily growth hormone therapy, confirming that the convenience of weekly dosing does not compromise therapeutic efficacy.
Ngenla is indicated exclusively for the treatment of growth failure due to inadequate secretion of endogenous growth hormone in pediatric patients aged 3 years and older. It is not indicated for other causes of short stature, and it should not be used after the growth plates (epiphyses) have closed.
What Should You Know Before Taking Ngenla?
Quick Answer: Ngenla must not be used in patients with active tumors, closed growth plates, or during acute critical illness. Regular medical monitoring is essential, and several conditions require special precautions before starting treatment.
Contraindications
There are several situations in which Ngenla must not be used. Understanding these contraindications is critical for patient safety. Do not use Ngenla in any of the following circumstances:
- You or your child is allergic to somatrogon or any of the other ingredients in this medicine.
- There is an active tumor (cancer). Tumors must be inactive and cancer treatment must be completed before starting Ngenla.
- Growth has stopped because the growth plates have closed (closed epiphyses), meaning the bones have stopped growing.
- The patient is acutely critically ill, such as from complications after open heart surgery, abdominal surgery, acute respiratory failure, or multiple trauma.
If you or your child is about to undergo or has recently undergone major surgery, or is being hospitalized for any reason, inform all healthcare providers that growth hormone therapy is being used. Growth hormone can affect the body's response to critical illness, and temporary discontinuation may be necessary.
Warnings and Precautions
Several medical conditions and situations require careful monitoring and discussion with a healthcare provider before and during treatment with Ngenla. These warnings are based on clinical experience with growth hormone therapies more broadly, as well as specific data from the Ngenla clinical development program.
Allergic Reactions: If a serious allergic reaction occurs, stop using Ngenla and contact a healthcare provider immediately. Serious allergic reactions including hypersensitivity, anaphylaxis, and angioedema (difficulty breathing or swallowing, or swelling of the face, lips, throat, or tongue) have been reported. Seek emergency medical attention if you notice difficulty breathing, facial or throat swelling, skin rash, or fever after injection.
Adrenal Insufficiency: Patients receiving replacement therapy with adrenocortical hormones (glucocorticoids) should be monitored regularly, as the glucocorticoid dose may need adjustment. Growth hormone can reduce the effectiveness of glucocorticoid replacement.
Thyroid Function: Growth hormone therapy can unmask previously undiagnosed central hypothyroidism or worsen existing hypothyroidism. Thyroid function should be monitored periodically, and thyroid hormone replacement should be initiated or adjusted as needed to ensure Ngenla works properly.
Prader-Willi Syndrome: Patients with Prader-Willi syndrome should not be treated with Ngenla unless they have confirmed growth hormone deficiency. There have been reports of sudden death in patients with Prader-Willi syndrome who were treated with growth hormone, particularly in those with severe obesity, history of respiratory impairment, sleep apnea, or unidentified respiratory infection.
Glucose Metabolism: Growth hormone can increase blood sugar levels (hyperglycemia). Patients should be monitored for changes in glucose metabolism. In patients with diabetes mellitus or those on insulin or other antidiabetic medications, the dose of these medications may need adjustment. Patients with diabetes and severe or worsening diabetic eye disease (retinopathy) should not be treated with Ngenla.
Tumor History: Patients with a history of any type of tumor should be monitored closely. While there is no conclusive evidence that growth hormone therapy increases the risk of tumor recurrence, vigilance is warranted.
Intracranial Hypertension: If visual changes, severe or recurrent headaches accompanied by nausea or vomiting, or problems with muscle coordination or swallowing occur (especially at the start of treatment), contact a healthcare provider immediately. These may be signs of a temporary increase in intracranial pressure (pseudotumor cerebri).
Pancreatitis: If severe abdominal pain develops during treatment, seek medical attention as this may indicate inflammation of the pancreas (pancreatitis).
Scoliosis: Patients who develop a sideways curvature of the spine (scoliosis) should be monitored more frequently by a healthcare provider, as scoliosis may progress during periods of rapid growth.
Slipped Capital Femoral Epiphysis: If a child begins to limp or develops hip or knee pain during the growth period, seek immediate medical attention. This may indicate slipped capital femoral epiphysis, a condition that can occur during periods of rapid growth.
Pregnancy and Breastfeeding
Ngenla has not been studied in pregnant women, and it is not known whether somatrogon can cause harm to an unborn baby. Therefore, Ngenla should be avoided during pregnancy. Women of childbearing potential should use reliable contraception while using Ngenla.
It is not known whether somatrogon passes into breast milk. If you are breastfeeding or planning to breastfeed, discuss this with your healthcare provider. Together, you can decide whether to discontinue breastfeeding or discontinue Ngenla, considering the benefit of breastfeeding for the infant and the benefit of treatment for you.
Ngenla does not affect the ability to drive vehicles or operate machinery. No special precautions are necessary.
How Does Ngenla Interact with Other Drugs?
Quick Answer: Ngenla can interact with glucocorticoids, insulin and other antidiabetic drugs, thyroid hormones, oral estrogens, ciclosporin, and antiepileptic medications. Dose adjustments of these drugs may be required during growth hormone therapy.
Always inform your healthcare provider about all medications being used, including prescription drugs, over-the-counter medicines, and herbal supplements. Several important drug interactions have been identified with growth hormone therapy, and careful monitoring with potential dose adjustments is essential.
| Interacting Drug | Effect | Action Required |
|---|---|---|
| Glucocorticoids (e.g., hydrocortisone, prednisolone) | May reduce growth-promoting effect of Ngenla | Regular monitoring; glucocorticoid dose may need adjustment |
| Insulin & antidiabetic agents | Ngenla may increase blood sugar, reducing efficacy of diabetes medications | Monitor blood glucose; insulin or antidiabetic dose may need adjustment |
| Thyroid hormones (e.g., levothyroxine) | Growth hormone may unmask or worsen hypothyroidism | Monitor thyroid function; thyroid hormone dose may need adjustment |
| Oral estrogen (oral contraceptives, HRT) | Oral estrogen may reduce IGF-1 response to growth hormone | Ngenla dose may need to be increased |
| Ciclosporin | Growth hormone may alter ciclosporin metabolism | Monitor ciclosporin levels; dose adjustment may be needed |
| Antiepileptic drugs (e.g., carbamazepine, valproate) | Growth hormone may alter metabolism of antiepileptic drugs | Monitor seizure control; antiepileptic dose may need adjustment |
The interactions listed above are based on pharmacological mechanisms shared by all growth hormone products, as well as specific guidance from the Ngenla Summary of Product Characteristics (SmPC). Healthcare providers should review all concomitant medications at each visit and consider potential interactions when initiating or adjusting any of the drugs listed above.
What Is the Correct Dosage of Ngenla?
Quick Answer: The recommended dose of Ngenla is 0.66 mg per kg body weight, administered once weekly by subcutaneous injection. The dose is individualized by the prescribing physician based on the child's weight.
Ngenla should only be prescribed by a physician experienced in growth hormone therapy who has confirmed the diagnosis of growth hormone deficiency. The dosage is weight-based and given once per week on the same day each week. This weekly dosing schedule is a significant improvement over traditional daily growth hormone injections.
Recommended Dose
Children and Adolescents (aged 3 years and older)
Dose: 0.66 mg/kg body weight, once weekly
Route: Subcutaneous injection (under the skin)
Injection sites: Abdomen, thighs, buttocks, or upper arms. Rotate injection sites with each dose.
Pen sizes: 24 mg pen (delivers 0.2–12 mg per injection) and 60 mg pen (delivers 0.5–30 mg per injection).
| Body Weight | Weekly Dose (0.66 mg/kg) | Recommended Pen |
|---|---|---|
| 15 kg | 9.9 mg | 24 mg pen |
| 25 kg | 16.5 mg | 60 mg pen |
| 35 kg | 23.1 mg | 60 mg pen |
| 50 kg | 33.0 mg | 60 mg pen (may require 2 injections) |
If a patient has been previously treated with daily growth hormone injections, the physician will instruct the patient to wait until the day after the last daily injection before giving the first dose of Ngenla, and then continue with Ngenla once weekly.
How to Administer Ngenla
Ngenla is supplied as a prefilled multi-dose injection pen. Before using the pen for the first time, a healthcare provider will demonstrate the proper injection technique. The injection should be given subcutaneously (under the skin) and must not be injected into a blood vessel or muscle.
The best injection sites are the abdomen, thighs, buttocks, or upper arms. When injecting in the upper arms or buttocks, this should be done by a caregiver (typically a parent). Rotate the injection site with each dose to reduce the risk of injection site reactions. If more than one injection is needed to deliver the full dose (when the dose exceeds the maximum single-injection capacity of the pen), use different injection sites for each injection.
Preparing a New Pen (Priming)
Each new pen must be primed before the first use to remove air bubbles and ensure accurate dosing. To prime: turn the dosing dial to 0.4, hold the pen with the needle pointing up, gently tap the cartridge holder to move any bubbles to the top, then press the injection button until a drop of liquid appears at the needle tip. If no drop appears, repeat the priming process up to 5 times. If still no liquid is visible, try with a new needle. If the pen still does not prime, contact your healthcare provider and use a new pen.
Weekly Injection Day
Ngenla should be injected on the same day each week. Record which day you administer the injection to maintain consistency. If you need to change the day, ensure at least 3 days have passed since the last injection, then continue on the new day each week going forward.
Missed Dose
- 3 days or less since the missed dose: Take it as soon as you remember, then continue with the next injection on the regular scheduled day.
- More than 3 days since the missed dose: Skip the missed dose entirely and take the next injection on the regular scheduled day.
- Never take a double dose to make up for a forgotten injection.
Overdose
If too much Ngenla has been injected, contact a healthcare provider immediately. An overdose may cause blood sugar levels to drop initially (hypoglycemia) and subsequently rise (hyperglycemia). Long-term overdosage could result in signs and symptoms consistent with the known effects of excess human growth hormone, such as overgrowth of certain body parts (acromegaly) and fluid retention.
Stopping Treatment
Do not stop using Ngenla without consulting your healthcare provider. Premature discontinuation of growth hormone therapy may result in the child not reaching their full growth potential. Your healthcare provider will determine the appropriate time to stop treatment based on growth velocity, bone age, and other clinical factors.
What Are the Side Effects of Ngenla?
Quick Answer: The most common side effects are headache, injection site reactions, and fever. Most side effects are mild to moderate and resolve without treatment. Serious allergic reactions are rare but require immediate medical attention.
Like all medicines, Ngenla can cause side effects, although not everyone will experience them. The side effects observed in clinical trials with Ngenla are consistent with the known safety profile of growth hormone therapies. Below is a comprehensive overview organized by frequency of occurrence.
Very Common
May affect more than 1 in 10 patients
- Headache
- Injection site reactions (bleeding, inflammation, itching, pain, redness, soreness, tingling, tenderness, or warmth)
- Fever (pyrexia)
Common
May affect up to 1 in 10 patients
- Decreased number of red blood cells (anemia)
- Increased number of eosinophils in the blood (eosinophilia)
- Decreased thyroid hormone levels (hypothyroidism)
- Allergic inflammation of the conjunctiva (allergic conjunctivitis)
- Joint pain (arthralgia)
- Pain in arms or legs (pain in extremity)
Uncommon
May affect up to 1 in 100 patients
- Adrenal insufficiency (the adrenal glands do not produce enough steroid hormones)
- Skin rash
Other Potential Side Effects (reported with other growth hormone products)
Not observed with Ngenla but known from the growth hormone class
- Type 2 diabetes mellitus
- Increased intracranial pressure (causing severe headache, visual disturbances, or vomiting)
- Numbness or tingling (paresthesia)
- Joint or muscle pain (arthralgia, myalgia)
- Breast enlargement in males (gynecomastia)
- Fluid retention (manifesting as swollen fingers or ankles)
- Facial swelling
- Pancreatitis (inflammation of the pancreas causing abdominal pain, nausea, vomiting, or diarrhea)
- Tissue growth (benign or malignant neoplasms)
Stop using Ngenla and seek emergency medical care if you experience signs of a severe allergic reaction, including difficulty breathing, swelling of the face, mouth, or tongue, widespread rash, or high fever. In very rare cases, the preservative metacresol contained in Ngenla may cause inflammation (swelling) of the muscles. Report any muscle pain or pain at the injection site to your healthcare provider.
If you experience any side effects, talk to your healthcare provider, pharmacist, or nurse. This includes any possible side effects not listed here. Reporting side effects helps regulatory authorities continuously monitor the benefit-risk balance of the medicine.
How Should You Store Ngenla?
Quick Answer: Store Ngenla in a refrigerator (2–8°C) before and after first use. After opening, use within 28 days. It can be kept at room temperature (up to 32°C) for up to 4 hours per injection, maximum 5 times total. Never freeze.
Proper storage of Ngenla is essential to maintain the effectiveness and safety of the medicine. The prefilled injection pen contains a biological product that is sensitive to temperature, light, and physical handling.
Before First Use
- Store in a refrigerator at 2–8°C (36–46°F).
- Keep in the outer carton to protect from light.
- The pen may be removed from the refrigerator and kept at room temperature (up to 32°C / 90°F) for up to 4 hours before use.
- Do not use if the solution appears cloudy, dark yellow, or contains flakes or particles.
- Do not shake the pen, as this may damage the medicine.
- Do not use after the expiration date printed on the pen label and carton.
After First Use
- Use within 28 days of the first injection.
- Store in the refrigerator (2–8°C) between uses with the pen cap on.
- Do not freeze the pen.
- Do not store the pen with a needle attached.
- May be kept at room temperature (up to 32°C) for up to 4 hours per injection, for a maximum of 5 occasions total.
- Return the pen to the refrigerator after each use.
- Discard the pen after 28 days, even if it still contains unused medicine.
- Discard if the pen has been exposed to temperatures above 32°C, or if it has been out of the refrigerator for more than 4 hours at any single occasion.
Write the date of first use on the pen label to help remember when to discard it. A small amount of medicine may remain in the pen after all doses have been correctly administered; this is normal and should not be used. Dispose of used pens and needles in a sharps container, not in household waste or sewage.
Keep this medicine out of the sight and reach of children. Do not dispose of medicines via wastewater or household waste. Ask your pharmacist how to properly dispose of medicines no longer being used, in accordance with local regulations.
What Does Ngenla Contain?
Quick Answer: Ngenla contains somatrogon as the active ingredient, available in 24 mg and 60 mg prefilled pens. Inactive ingredients include trisodium citrate dihydrate, citric acid monohydrate, L-histidine, sodium chloride, poloxamer 188, metacresol, and water for injections.
Active Ingredient
Somatrogon — a modified form of human growth hormone produced using recombinant DNA technology. It is a fusion protein consisting of human growth hormone and the C-terminal peptide of human chorionic gonadotropin (hCG), which extends its duration of action to enable once-weekly dosing.
Available Strengths
| Pen | Concentration | Total Content | Dose Range per Injection | Dose Increments |
|---|---|---|---|---|
| 24 mg pen (purple cap) | 20 mg/mL | 24 mg in 1.2 mL | 0.2 mg to 12 mg | 0.2 mg |
| 60 mg pen (blue cap) | 50 mg/mL | 60 mg in 1.2 mL | 0.5 mg to 30 mg | 0.5 mg |
Inactive Ingredients (Excipients)
- Trisodium citrate dihydrate (buffer)
- Citric acid monohydrate (pH adjustment)
- L-histidine (stabilizer)
- Sodium chloride (tonicity agent)
- Poloxamer 188 (surfactant)
- Metacresol (preservative)
- Water for injections (solvent)
Sodium content: This medicine contains less than 1 mmol (23 mg) sodium per dose, meaning it is essentially sodium-free.
Metacresol note: Ngenla contains the preservative metacresol. In very rare cases, metacresol may cause inflammation (swelling) in the muscles. If muscle pain or pain at the injection site occurs, inform your healthcare provider.
Appearance
Ngenla is a clear and colorless to slightly light yellow solution for injection in a prefilled pen. The 24 mg pen has a purple cap, dosing button, and label. The 60 mg pen has a blue cap, dosing button, and label. Each pack contains 1 prefilled injection pen.
Marketing Authorization Holder and Manufacturer
Marketing Authorization Holder: Pfizer Europe MA EEIG, Boulevard de la Plaine 17, 1050 Brussels, Belgium.
Manufacturer: Pfizer Manufacturing Belgium NV, Rijksweg 12, 2870 Puurs-Sint-Amands, Belgium.
Frequently Asked Questions About Ngenla
The primary advantage of Ngenla is its once-weekly dosing schedule. Traditional growth hormone treatments require daily injections, which can be burdensome for children and families. Ngenla reduces the number of injections from approximately 365 per year to just 52, significantly improving treatment convenience and potentially improving adherence. Clinical studies have shown that Ngenla achieves comparable growth rates to daily growth hormone therapy.
Ngenla is currently approved only for use in children and adolescents aged 3 years and older with growth hormone deficiency. It is not indicated for use in adults. Once the growth plates have closed and linear growth has ceased, treatment with Ngenla should be discontinued. Adults with growth hormone deficiency may be treated with other growth hormone products approved for adult use.
The duration of treatment with Ngenla depends on the individual child's growth response and when their growth plates close. Treatment typically continues throughout childhood and adolescence until a satisfactory adult height is achieved, growth velocity has decreased significantly, or the growth plates have closed. This may span several years. Your child's healthcare provider will monitor growth regularly and determine when treatment should be stopped.
The Ngenla pen is compatible with pen needles ranging from 4 mm to 8 mm in length and between 30G and 32G in gauge. Specifically tested compatible needles include: NovoFine Plus (32G), NovoFine (31G), BD Ultra-Fine and BD Micro-Fine (31G), and safety needles such as BD AutoShield Duo (30G) and NovoFine AutoCover (30G). Always use a new sterile needle for each injection. Your healthcare provider can recommend the most appropriate needle type for you or your child.
No. Ngenla is specifically indicated for children and adolescents with confirmed growth hormone deficiency (GHD). It is not approved for the treatment of short stature due to other causes such as Turner syndrome, chronic kidney disease, small for gestational age, or idiopathic short stature. A thorough diagnostic evaluation, including growth hormone stimulation tests, must confirm GHD before treatment is initiated.
If the pen does not contain enough medicine for a full dose, you have two options: (1) inject the remaining amount from the current pen, then use a new pen to deliver the rest of the dose (subtracting the amount already injected), or (2) discard the current pen and use a new pen for the full dose. If your dose exceeds the maximum single-injection capacity of the pen (12 mg for the 24 mg pen, 30 mg for the 60 mg pen), you will need to give more than one injection using different injection sites.
References
- European Medicines Agency (EMA). Ngenla (somatrogon) — Summary of Product Characteristics. Last updated 2025. Available at: EMA - Ngenla.
- Deal CL, Tony M, Höybye C, et al. Growth Hormone Research Society workshop summary: consensus guidelines for recombinant human growth hormone therapy in Prader-Willi syndrome. J Clin Endocrinol Metab. 2013;98(6):E1072-E1087. doi:10.1210/jc.2012-3888.
- Pfizer Inc. Ngenla (somatrogon-ghla) prescribing information. U.S. Food and Drug Administration. 2023.
- Bright GM, Do MT, McKew JC, et al. Development of somatrogon, a long-acting growth hormone: results of phase 3 clinical trials. J Clin Endocrinol Metab. 2022;107(9):e3990-e3998.
- Endocrine Society. Clinical practice guideline: evaluation and treatment of adult growth hormone deficiency. J Clin Endocrinol Metab. 2019;104(11):4785-4794.
- World Health Organization (WHO). WHO Model List of Essential Medicines — 23rd List. Geneva: WHO; 2023.
- Fisher BG, Acerini CL. Understanding the growth hormone therapy adherence paradigm: a systematic review. Horm Res Paediatr. 2013;79(4):189-196. doi:10.1159/000350251.
- National Institute for Health and Care Excellence (NICE). Human growth hormone (somatropin) for the treatment of growth failure in children. Technology appraisal guidance [TA188]. 2010; reviewed 2023.
Medical Editorial Team
Medical Content
Written by iMedic Medical Editorial Team — specialists in endocrinology and pediatric medicine with documented clinical experience.
Medical Review
Reviewed by iMedic Medical Review Board — independent panel following EMA, FDA, and Endocrine Society guidelines.
Evidence Level: 1A (systematic reviews and randomized controlled trials). Guideline Adherence: EMA SmPC, FDA PI, Endocrine Society. Conflicts of Interest: None. Last Reviewed: .