Somatrogon (Ngenla)_Dosage, benefits & legal status
Also known as Ngenla, somatrogon-ghla, MOD-4023
Weekly because it is wrapped in carbohydrate, not because it is modified cleverly.
Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.
What is Somatrogon (Ngenla)?
Plain language first. The technical label stays, but it never stands alone.Overview
This is the third design for a weekly growth hormone, and the crudest in concept: take growth hormone and attach three copies of a tail borrowed from a pregnancy hormone, chosen because those tails carry heavy sugar chains that make the kidneys slow to clear the molecule. It works, and it is approved, but it has one indication and has not gained another since 2023, and it matched daily growth hormone rather than beating it. Its dose number, 0.66 mg/kg, is the largest of the three, and that is not because it is a stronger drug: it is because the number weighs the entire fusion protein, most of which is not growth hormone.
Somatrogon is a fusion protein produced in Chinese hamster ovary cells. The label describes one copy of the C-terminal peptide from the beta chain of human chorionic gonadotropin at the N-terminus, plus two copies in tandem at the C-terminus, giving three CTP copies in total around a growth hormone core. The approximate molecular weight is 40 kilodaltons, a substantial part of which is O-linked carbohydrate carried on those CTP segments. The population pharmacokinetic effective half-life is 37.7 hours, and the label states this allows for weekly dosing. The dose is 0.66 mg/kg once weekly, counting the whole fusion protein. The only United States indication is pediatric growth hormone deficiency from age 3.
What it's used for
Growth failure from inadequate secretion of growth hormone in children aged 3 years and older. That is its only United States indication; there is no adult indication.
How does Somatrogon (Ngenla) work?
What it does in the body, and where.The design question for a weekly growth hormone is how to stop the kidneys clearing it within hours. This product answers it with bulk and sugar.
- 01Three tails from a pregnancy hormoneHuman chorionic gonadotropin, the hormone a pregnancy test detects, carries a C-terminal peptide on its beta chain that is unusually heavily decorated with sugar chains. That segment is what keeps hCG in circulation. Somatrogon attaches three copies of it to growth hormone: one at the front and two in tandem at the back, per the label.
- 02Why sugar slows clearanceThe kidney filters by size and charge. O-linked sugar chains add both bulk and negative charge, so the molecule is filtered far more slowly than bare growth hormone. The finished glycoprotein is about 40 kilodaltons against roughly 22 for growth hormone itself, and a substantial share of that extra mass is carbohydrate rather than protein.
- 03What that means for manufacture, and for supplySugar chains are added by cells, not chemists. The product has to be grown in Chinese hamster ovary cells that attach the carbohydrate correctly, so there is no synthetic route to it at all. That is the concrete reason this compound does not appear in research-peptide channels: unlike a short peptide, nobody can make it on a synthesizer.
- 04The weakest half-life story of the threeThe label reports a population pharmacokinetic estimated effective half-life of 37.7 hours and says this allows for weekly dosing. Two cautions. It is the longest of the three figures but still well under two days. Also, an effective half-life derived from a population model is a weaker kind of number than a directly observed terminal half-life, so it should not be set beside the other labels' figures as though all three were measured the same way.
A schematic of the compound's mechanism, not a diagnostic image.
What else is it used for?
Each group carries its own evidence level.Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.
The thinnest regulatory record of the three
FDA-approved- RegulatoryApproved June 2023 for pediatric growth hormone deficiency from age 3, and no indication has been added since. It carries no efficacy supplements.
- RegulatoryIt is the only one of the three long-acting growth hormones with no adult indication in the United States.
- Human trialIts pivotal trial showed non-inferiority to daily somatropin on height velocity, not superiority.
How it lasts, and why it cannot be synthesized
FDA-approved- RegulatoryThree copies of the hCG beta chain C-terminal peptide, one at the N-terminus and two in tandem at the C-terminus, carrying O-linked sugar chains that slow kidney clearance. Approximately 40 kilodaltons in total.
- RegulatoryPopulation pharmacokinetic effective half-life of 37.7 hours. The longest of the three products, and still under two days. An effective half-life from a population model is a weaker figure than a directly observed one.
- lab-analysisSugar chains are attached by cells, so the product requires mammalian cell culture and has no synthetic route. That is the concrete reason it does not appear in research-peptide supply.
An identity detail that is not in the US label
none- No dataThe total residue count of 275, with growth hormone at positions 29 to 219 and CTP segments at 1 to 28, 220 to 247 and 248 to 275, comes from Japan's regulatory review. Neither the United States nor the European documents state a residue count.
The dose is the thing most often misread. 0.66 mg/kg a week looks like a far larger dose than somapacitan's 0.24 or Skytrofa's 0.24, and it is not delivering proportionally more growth hormone: the number weighs an entire fusion protein whose extra mass is three sugar-laden peptide tails. Second, this is routinely described as a growth hormone analog, and the label does use that phrase, but it is a fusion protein rather than a modified hormone, and the distinction matters for how it is made and why it lasts. Third, the 37.7 hour half-life is an effective half-life estimated from a population model rather than an observed terminal half-life, so comparing it directly with the other labels' numbers overstates how comparable they are. Fourth, a total residue count of 275 circulates for this molecule; it is real but comes from Japan's regulatory review, not from the US or EU labels.
The published record
Papers and trials about Somatrogon (Ngenla)
Searched: somatrogon, Ngenla, MOD-4023.
Left out: growth hormone (tens of thousands of unrelated records); somatropin (has its own slug as HGH); CTP (an abbreviation colliding with cytidine triphosphate and many unrelated terms); chorionic gonadotropin (the hormone the tails come from, with its own enormous fertility literature and its own slug as HCG); fusion protein (an architecture shared with hundreds of unrelated biologics).
57 papers tagged human · 32 not reviews or lab · 12 clinical trial publications
9 registered trials · 3 with posted results
Furthest stage reached: Approved in the US
Counted from Europe PMC indexing, not read by a person; a human tag can land on reviews, commentary or lab papers; clinical trial publications is the narrower count.
At a glance
Four things to know about Somatrogon (Ngenla)
Evidence
FDA-approved
Category
Growth hormone
Common vial
Varies
Half-life
About 38 hours
How much, and do you cycle it?
The range, and whether you take breaks.0.66 mg/kg weekly, once weekly. Continuous weekly dosing while growth plates are open FDA label
Growth hormone replacement in children is continuous treatment while the growth plates remain open. No cycling scheme applies.
How long does it stay in the body?
The half-life, and where the figure comes from.About 38 hoursFDA label
The label gives a mean population pharmacokinetic estimated effective half-life of 37.7 hours and states that this allows for weekly dosing. It is the longest of the three long-acting growth hormones and still under two days. Note that an effective half-life from a population model is a different kind of measurement from an observed terminal half-life.
Source: Ngenla prescribing information, population pharmacokinetic estimate
You can compare this against the whole library to see where it sits.
How is it given?
Dosing context and source notes.Supplied as a pen or prefilled syringe, so there is nothing to mix.
Label dose: 0.66 mg/kg per week.
0.66 mg/kg once weekly on actual body weight. The figure weighs the entire fusion protein, including three heavily glycosylated CTP segments, so it is roughly three times somapacitan's and Skytrofa's numbers without delivering three times the growth hormone. A missed dose may be given within 3 days. Recorded as a prescribing fact, not as guidance.
How do you store it?
Before mixing, and after.Follow the storage on the product label.
Somatrogon (Ngenla) is supplied as a finished product, so its label sets the storage. Pens, prefilled syringes, implants, tablets and ready-made solutions are used as supplied. Kits that include a powder are mixed just before the dose and usually used straight away, not kept for weeks. Many injectable products go in the fridge and must not be frozen, while others are kept at room temperature, so check the pack or ask the pharmacist.
What are the side effects and cautions?
Known cautions and warnings for this compound.Who should avoid it
- Any use outside a prescription: it requires mammalian cell culture with correct sugar attachment and cannot be synthesized, and we found no vendor offering it
- Adults, since there is no adult indication in the United States
- Comparing its 0.66 mg/kg against the other two products' numbers, because it weighs the whole fusion protein
Stop and get help
- Signs of raised pressure inside the skull, such as persistent headache with vision changes or vomiting
- Signs of an allergic reaction to the injection
Common effects
- Injection-site reactions, headache and joint pain, as with growth hormone treatment generally
Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.
Is Somatrogon (Ngenla) approved?
And where the numbers on this page come from.Yes. Somatrogon (Ngenla) is FDA approved and available on prescription in the United States. It is also approved in the European Union, Japan, and Canada.
- Approval statusFDA-approved
- RouteUnder the skin (weekly injection)
- Checked30 October 2026
- Approved outside the USEuropean Union, Japan, Canada.This does not change the United States position above.
- DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
- Vial sizeFrom what vendors typically list; not a recommendation.
- Sources
What has happened recently
FDA-approved under BLA 761184 in June 2023 for pediatric growth hormone deficiency in children aged 3 and older. It carries no efficacy supplements, meaning no indication has been added since approval and there is no adult use in the United States. That is the clearest difference between this product and the other two weekly growth hormones, both of which cover adults and one of which gained three new pediatric indications in February 2026. The 2026 WADA Prohibited List names somatrogon in section S2.2.3 as a growth hormone analog. The United Kingdom's Advisory Council on the Misuse of Drugs assessed it in 2025; the few post-marketing reports the medicines regulator described concern non-adherence rather than performance use. One identity detail worth care: the total residue count of 275, with the growth hormone core at positions 29 to 219 and CTP segments at 1 to 28, 220 to 247 and 248 to 275, appears in Japan's regulatory review rather than in the United States or European documents, so it should be attributed there.
Banned in drug-tested sport. Most research peptides are prohibited under WADA's S0 category, which covers any substance with no approval from any regulatory authority for human use. That means a compound can be banned without ever being named on the prohibited list. Check with your own anti-doping authority rather than assuming absence from the list means permitted.
You can compare this against the whole library, or read how to check a seller.
What else is like Somatrogon (Ngenla)?
Others in Growth hormone peptides, side by side.If you're weighing Somatrogon (Ngenla), it's worth reading Tesamorelin, Ipamorelin, and CJC-1295 no DAC (Mod GRF 1-29) in the same class.
Weekly because it is wrapped in carbohydrate, not because it is modified cleverly.
- Dose
- 0.66 mg/kg weekly
- How often
- Once weekly
An approved shot proven to shrink stubborn belly fat.
- Dose
- 1.28 up to 2 mg per day, depending on which product you have
- How often
- Daily
A gentle shot that nudges your body to release its own growth hormone.
- Dose
- 0.2 up to 0.3 mg per dose (start low, increase slowly)
- How often
- Daily, often at night
A short-acting growth-hormone pulse, usually paired with ipamorelin.
- Dose
- 0.1 mg per dose
- How often
- Daily to 2x daily
Guides for this compound
- How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
- How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
- mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Sources
- Ngenla (somatrogon-ghla) prescribing information(2026)The label, read through the FDA's own label API. Describes a fusion protein produced in Chinese Hamster Ovary cells with one copy of the C-terminal peptide from the beta chain of human chorionic gonadotropin at the N-terminus and two copies in tandem at the C-terminus, and an approximate molecular weight of 40 kDa. The label states no total residue count. Indication: pediatric patients aged 3 years and older with growth failure due to inadequate secretion of endogenous growth hormone, and no other indication. Dose 0.66 mg/kg once weekly on actual body weight. The mean population pharmacokinetic estimated effective half-life is 37.7 hours, and the label says this allows for weekly dosing. A missed dose should be given within 3 days, and if more than 3 days have passed the dose is skipped. No boxed warning appears.
- WADA 2026 Prohibited List, section S2.2.3(2026)Section S2.2.3 names lonapegsomatropin, somapacitan and somatrogon among the growth hormone analogs, and AOD-9604 and hGH 176-191 among the fragments. Section S2.2.4 names tesamorelin, sermorelin, CJC-1295, ipamorelin and ibutamoren, also called MK-677.
- Maniatis and colleagues, Journal of the Endocrine Society, treatment burden study(2022)Treatment Burden of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Randomized Study, volume 6, issue 10, article bvac117. Cited because the argument for a weekly growth hormone rests on burden rather than on better growth: this product matched daily treatment on height velocity, so the case for it is the injection count. DOI resolved at Crossref.
Beyond these, 99 records are indexed. Browse the records