Somatrogon (Ngenla)
A once-weekly growth hormone fused to short hCG peptides. The US label covers children.
Checked 2026-10-22 against the US label Researched and written by Kymata Health Editorial Report an error
- Sold as
- Ngenla
- Full name
- somatrogon-ghla
- Maker
- Pfizer (developed with OPKO Health)
- Status
- Prescription only; US label since 2023
- Sport
- WADA S2, prohibited at all times
What is somatrogon?
Short answer
Somatrogon is human growth hormone fused to three copies of the C-terminal peptide of hCG, the pregnancy hormone. Those peptides slow its clearance, so it is injected once a week. Pfizer sells it as Ngenla; the US label covers children 3 and older with growth hormone deficiency.
How it lasts a week
The label describes one copy of the hCG C-terminal peptide (CTP) at the start of the GH chain and two at its end, giving a protein of about 40 kDa. The larger molecule is cleared more slowly: the effective half-life in children is 37.7 hours, and it stays in the circulation for about 8 days after the last dose. (Ngenla label)
Who is Ngenla approved for?
The US label's indications, in its own terms.
US label indications
1- Children aged 3 years and older with growth failure from too little GH. No adult indication in the US.
What dose does the Ngenla label give?
What the label states, for the patients it covers. Not a dose for anyone reading this: the prescriber sets it.
On the label
| Label wording, summarised | Source |
|---|---|
| 0.66 mg/kg of actual body weight, once weekly, under the skin. | (Ngenla label) |
How long does somatrogon last, and when is IGF-1 checked?
Pharmacokinetics
| Measure | Label value | Source |
|---|---|---|
| Effective half-life (children) | 37.7 h | (Ngenla label) |
| Time to peak | 6 to 25 h (median 11 h) | (Ngenla label) |
| Present after the last dose | About 8 days | (Ngenla label) |
| IGF-1 | Peaks about 2 days after a dose; the weekly average is reached about 4 days after | (Ngenla label) |
IGF-1 timing IGF-1 peaks about 2 days after a dose and averages its weekly level about 4 days after; the label gives no adult titration because it has no adult indication. (Ngenla label)
What are the warnings for Ngenla?
From the current US label. A clinician weighs them for each patient.
Status Prescription only. Ngenla has had a US label since 2023 (Pfizer (developed with OPKO Health)). WADA prohibits it at all times (S2). (Ngenla label; WADA Prohibited List 2026)
Warnings shared by every growth hormone label
| Topic | What the labels say |
|---|---|
| Acute critical illness | Contraindicated after open-heart or abdominal surgery, multiple trauma or acute respiratory failure; two ICU trials found higher mortality with GH. |
| Active cancer | Contraindicated with active malignancy; a preexisting one must be inactive and treated. Childhood cancer survivors given head radiation had more second tumours, mostly meningiomas. |
| Prader-Willi syndrome | Deaths reported in children with severe obesity, airway obstruction, sleep apnea or respiratory infection. |
| Glucose | Can lower insulin sensitivity and unmask impaired glucose tolerance or diabetes. |
| Intracranial hypertension | Papilledema, headache and visual changes, usually in the first 8 weeks; eye exams before and during treatment. |
| Fluid retention | Edema, joint and muscle pain, carpal tunnel: usually transient and dose dependent. |
| Adrenal and thyroid | May unmask low cortisol (central hypoadrenalism) or central hypothyroidism; thyroid tests during treatment. |
| Children: hips and spine | Slipped capital femoral epiphysis and progression of scoliosis during rapid growth. |
| Other | Pancreatitis (rare), lipoatrophy at a repeated site, contraindicated in active proliferative or severe non-proliferative diabetic retinopathy. |
Frequently asked questions
Questions
- Can adults use Ngenla?
- The US label covers only children aged 3 and older with growth hormone deficiency.
- Why does somatrogon last a week?
- It carries three short peptides from hCG, which make the molecule larger (about 40 kDa) and slow its clearance: the effective half-life in children is 37.7 hours.
- Is somatrogon banned in sport?
- Yes. WADA lists somatrogon under S2, prohibited at all times.
The growth hormone family
GH itself, the drugs that make the pituitary release more of it, and IGF-1 downstream. Half-lives are human values.
Three ways to raise GH
| Class | Acts on |
|---|---|
| GHRH analog | GHRH receptor on the pituitary (cAMP) |
| Ghrelin-receptor agonist | Ghrelin receptor (GHS-R1a) in hypothalamus and pituitary |
| Growth hormone (daily) | GH receptor directly; bypasses the pituitary |
| Growth hormone (weekly) (this page) | GH receptor directly, released over a week |
| IGF-1 | IGF-1 receptor, downstream of GH |
Compared
16 agents| Agent | Class | Labelled product | Half-life (human) | Taken |
|---|---|---|---|---|
| Somatropin (rhGH) | Growth hormone (daily) | Genotropin, Humatrope, Norditropin, Omnitrope, Zomacton, Serostim | 2 to 3.8 h (SC, across labels) (Humatrope label) | Daily injection (label) |
| Somapacitan | Growth hormone (weekly) | Sogroya | about 2 to 3 days (adults) (Sogroya label) | Weekly injection (label) |
| Somatrogon | Growth hormone (weekly) | Ngenla | 37.7 h (effective, children) (Ngenla label) | Weekly injection (label) |
| Lonapegsomatropin | Growth hormone (weekly) | Skytrofa | about 31 h (prodrug, children) (Skytrofa label) | Weekly injection (label) |
| Tesamorelin | GHRH analog | Egrifta SV, Egrifta WR | 8 to 38 min (by formulation and study) (Egrifta WR label) | Daily injection (label) |
| Sermorelin | GHRH analog | None | 6 to 7 min IV (EU product information) (Geref 50 SPC (HPRA)) | Daily injection in studies |
| CJC-1295 with DAC | GHRH analog | None | 5.8 to 8.1 days (Teichman 2006, JCEM) | Weekly or every other week in studies |
| CJC-1295 without DAC (mod GRF 1-29) | GHRH analog | None | No human value published | No human study published |
| Ipamorelin | Ghrelin-receptor agonist | None | 2 h (IV infusion) (Gobburu 1999, Pharm Res) | Single IV infusions in the human study |
| GHRP-2 | Ghrelin-receptor agonist | None | No human value published | IV test doses in studies |
| GHRP-6 | Ghrelin-receptor agonist | None | 2.5 h (IV) (Cabrales 2013, Eur J Pharm Sci) | IV test doses in studies |
| Hexarelin | Ghrelin-receptor agonist | None | No human value published | IV test doses in studies |
| MK-677 (ibutamoren) | Ghrelin-receptor agonist | None | No human value published | Daily by mouth in studies; GH raised over 24 h |
| Macimorelin | Ghrelin-receptor agonist | Macrilen | 4.1 h (Macrilen label) | One oral dose, as a diagnostic test (label) |
| Mecasermin (rhIGF-1) | IGF-1 | Increlex | 5.8 h (children) (Increlex label) | Twice daily with a meal (label) |
| IGF-1 LR3 | IGF-1 | None | No human value published | No human study published |
GH axis guides5
- Growth hormone: the GH axisHow GH is controlled, every agent compared
- GH pulse simulatorDose times against the natural sleep and exercise GH pulses, modelled from half-lives
- Long-acting growth hormones explainedThree once-weekly products, three different ways of making GH last a week.
- Somatropin brands comparedOne molecule, several names, and which are still on the US market.
- IGF-1 monitoring on GH-axis treatmentWhy IGF-1 is the test, when to draw it on weekly GH, and what the labels say to do with it.