Somapacitan is a long-acting form of human growth hormone (GH) made by Novo Nordisk and sold as Sogroya. It is the same 191-amino-acid protein as natural GH with one amino acid swapped and a small fatty side chain attached. That side chain grips albumin, the most common protein in blood, so the drug stays in circulation for days and only needs to be injected once a week instead of once a day.
The FDA approved Sogroya in August 2020 for adults with GH deficiency and in April 2023 for children with GH deficiency. The current label (revised February 2026) also covers children with short stature from three other causes. The label states plainly that it is not indicated for adults who are not GH deficient, and no trial has tested it for muscle or performance in healthy people.
This page summarizes what the FDA label, the phase 3 trials and regulators report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Drug class | Long-acting human growth hormone analog (albumin-binding) |
| Brand / approval | Sogroya (Novo Nordisk); FDA BLA 761156, approved August 28, 2020; EU authorization March 31, 2021 |
| Route | Subcutaneous injection, once weekly |
| Strengths | Prefilled pens of 5 mg, 10 mg and 15 mg per 1.5 mL |
| Labeled adult dose | Start 1.5 mg once weekly, titrate by IGF-1; maximum 8 mg once weekly |
| Labeled pediatric dose | 0.16 mg/kg/week (GH deficiency); 0.24 mg/kg/week (SGA, Noonan syndrome, idiopathic short stature) |
| Half-life (label) | About 2–3 days in adults with GH deficiency; about 34–37 h in children |
| Key mechanism fact | Reversible binding to albumin (over 99% protein bound) slows elimination |
| US status | Prescription biologic; not a controlled substance |
| WADA status | Prohibited at all times; named in class S2.2.3 |
What it is
Somapacitan (US name somapacitan-beco) is recombinant human GH produced in E. coli. Its protein part has 191 amino acids, the same length as natural GH. One leucine at position 101 is replaced by cysteine, and an albumin-binding side chain, made of an albumin binder and a hydrophilic spacer, is attached at that position. The whole molecule weighs 23,305 g/mol, of which the side chain is 1,191 g/mol (Sogroya label).
It acts like natural GH. It binds the GH receptor on target cells. Some effects come directly from that signal, and others come from insulin-like growth factor 1 (IGF-1), which the liver makes in response. IGF-1 is the blood marker doctors use to adjust the dose (Sogroya label).
For background on GH itself, including the daily somatropin products, its effects in GH-deficient and healthy adults, and its wider risks, see the HGH (human growth hormone) page. This page focuses on what is different about the weekly form. Drugs that make the body release more of its own GH, such as tesamorelin and ibutamoren, work by a different route.
How it compares with daily somatropin (Sogroya label; Johannsson et al., JCEM 2020):
| Feature | Somapacitan (Sogroya) | Daily somatropin |
|---|---|---|
| Structure | GH with one amino acid change plus an albumin-binding side chain | Identical to pituitary GH |
| Injections | Once weekly | Once daily |
| Elimination half-life | About 2–3 days (adults) | Much shorter (see the HGH page) |
| IGF-1 pattern | Peaks 2–4 days after each dose; larger peak-to-trough swings | Smaller peak-to-trough swings |
Pharmacokinetics
From the label’s clinical pharmacology section (Sogroya label):
| Parameter | Value |
|---|---|
| Time to peak concentration | 4–24 h in adults with GH deficiency; 8–25 h in children with GH deficiency |
| Time to steady state | 1–2 weekly doses |
| Protein binding | Over 99% |
| Volume of distribution (V/F) | About 14.6 L in adults with GH deficiency; 1.7 L in children with GH deficiency |
| Elimination half-life | About 2–3 days in adults with GH deficiency; about 34 h in children with GH deficiency; 36–37 h in children with SGA, Noonan syndrome or ISS |
| Washout | Cleared within one week after stopping |
| Excretion | About 81% in urine and 13% in feces, as breakdown products; no intact drug excreted |
IGF-1 peaks 2–4 days after each injection. For that reason the label says to draw IGF-1 for dose adjustment 3–4 days after the prior dose. In adults the IGF-1 response is less than dose-proportional (Sogroya label).
A radiolabel study gave seven healthy men a single 6 mg dose. Over 28 days, 94.0% of the dose was recovered, mostly in urine (80.9%), and no intact somapacitan was found in urine or feces. The body breaks the molecule down by cutting the linker between the protein and its side chain (Helleberg et al., Eur J Pharm Sci 2021).
Exposure differs by group (Sogroya label):
- Women, especially on oral estrogen, have lower exposure than men at the same dose.
- Adults over 65 have higher exposure than younger adults.
- Moderate liver impairment (Child-Pugh B) raised exposure (AUC) about 4.7-fold.
- Severe kidney impairment or hemodialysis raised exposure about 1.6–1.75-fold.
- Higher body weight lowers exposure.
Approved medical use
The current FDA label covers (Sogroya label):
- Adults: replacement of GH in adults with GH deficiency (the original 2020 approval) (FDA approval letter, 2020).
- Children aged 2.5 years and older with growth failure due to GH deficiency (added April 28, 2023) (FDA supplement approval letter, 2023).
- Children aged 2.5 years and older with short stature born small for gestational age (SGA) without catch-up growth by age 2, growth failure in Noonan syndrome, or idiopathic short stature (ISS), listed in the February 2026 label revision.
In the EU, Sogroya was authorized on March 31, 2021, for adults with GH deficiency and is also used in children from 3 years of age with growth failure due to GH deficiency (EMA).
Labeled dosing
| Population | Starting dose | Adjustment | Maximum |
|---|---|---|---|
| Adults with GH deficiency | 1.5 mg once weekly | Raise by about 0.5–1.5 mg every 2–4 weeks, guided by response and IGF-1 | 8 mg once weekly |
| Adults 65 and older | 1 mg once weekly | Smaller steps | 8 mg once weekly |
| Women on oral estrogen | 2 mg once weekly | As for adults | 8 mg once weekly |
| Adults with moderate liver impairment | 1 mg once weekly | Smaller steps | 4 mg once weekly |
| Children with GH deficiency | 0.16 mg/kg once weekly | Individualized by growth response | Not stated |
| Children with SGA, Noonan syndrome or ISS | 0.24 mg/kg once weekly | Individualized by growth response | Not stated |
The label does not recommend Sogroya for anyone with severe liver impairment or for children with moderate liver impairment. Treatment should be supervised by a clinician experienced in GH deficiency, and a fundoscopic (back of the eye) exam is required before starting (Sogroya label).
What the research shows
Adults with GH deficiency (REAL 1)
REAL 1 was a phase 3 trial in 17 countries. It randomized 301 adults with untreated GH deficiency to weekly somapacitan, weekly placebo (both double-blind) or open-label daily GH for 34 weeks, followed by a 52-week extension. The primary endpoint was the change in truncal (trunk) fat percentage, measured by DXA (dual-energy x-ray absorptiometry). The mean somapacitan dose was 2.56 mg/week (Johannsson et al., JCEM 2020).
Results at week 34 (observed mean changes; adjusted difference vs placebo with 95% CI):
| Outcome | Somapacitan (n=120) | Daily GH (n=119) | Placebo (n=61) | Somapacitan vs placebo |
|---|---|---|---|---|
| Truncal fat, percentage points | −1.16 | −2.47 | +0.63 | −1.53 (95% CI −2.68 to −0.38) |
| Visceral fat, % change | −9.4% | −8.3% | +6.3% | −15.7 (95% CI −23.4 to −8.0) |
| Total lean body mass | +1.38 kg | +1.44 kg | +0.31 kg | +1.14 kg (95% CI 0.46–1.83) |
| Appendicular skeletal muscle mass | +0.56 kg | +0.51 kg | −0.12 kg | +0.68 kg (95% CI 0.34–1.02) |
Somapacitan beat placebo on the primary endpoint. Compared with daily GH, the drop in truncal fat was smaller, while the changes in visceral fat and lean mass were similar. These effects were maintained through week 86. Mean IGF-1 SDS (standard deviation score, the number of standard deviations from the age- and sex-matched average) rose from −2.54 to −0.17 on somapacitan, while it stayed near −2.6 on placebo (Sogroya label; Johannsson et al., JCEM 2020).
These gains were measured in people who lacked GH to start with. The trial measured body composition and IGF-1, not strength or performance. A gain of about 1 kg of DXA lean mass over 34 weeks in GH-deficient adults says nothing about what the drug would do in someone with normal GH levels.
Children with GH deficiency (REAL 4)
REAL 4 randomized 200 untreated prepubertal children with GH deficiency, aged 2.5–11 years, 2:1 to somapacitan 0.16 mg/kg/week or daily somatropin (Norditropin) 0.034 mg/kg/day for 52 weeks (Miller et al., JCEM 2022). Height velocity was 11.2 cm/year with somapacitan vs 11.7 cm/year with daily GH, a difference of −0.5 cm/year (95% CI −1.1 to 0.2). This met the trial’s noninferiority criterion (Sogroya label).
Other causes of short stature in children
A phase 3 “basket” trial (one protocol, several conditions) compared somapacitan 0.24 mg/kg/week with daily somatropin for 52 weeks (Sogroya label):
| Condition | n | Somapacitan height velocity | Daily somatropin height velocity | Difference (95% CI) |
|---|---|---|---|---|
| Born SGA | 142 | 11.0 cm/year | 9.4 cm/year (0.035 mg/kg/day); 11.1 cm/year (0.067 mg/kg/day) | +1.6 (0.91 to 2.23); −0.1 (−0.75 to 0.60) |
| Noonan syndrome | 77 | 10.4 cm/year | 9.2 cm/year (0.050 mg/kg/day) | +1.2 (0.32 to 2.03) |
| Idiopathic short stature | 88 | 10.2 cm/year | 10.5 cm/year (0.050 mg/kg/day) | −0.3 (−1.00 to 0.42) |
The label notes that some comparator doses were below the maximum daily somatropin dose approved in the US for those conditions. In the same basket trial, 105 girls with Turner syndrome grew 9.0 cm/year on somapacitan vs 9.5 cm/year on daily GH, which met noninferiority (Mauras et al., JCEM 2026). Turner syndrome is not a labeled US indication for Sogroya.
Pooled evidence
A 2026 meta-analysis pooled 10 randomized trials (920 participants, children and adults) comparing somapacitan with daily Norditropin. It found no difference in height velocity (mean difference 0.12 cm/year, 95% CI −0.65 to 0.89) or in adverse events (risk ratio 1.03, 95% CI 0.88–1.20). IGF-1 SDS was slightly higher with somapacitan (mean difference 0.24, 95% CI 0.02–0.46) (Azhar et al., Endocrine 2026).
Side effects and risks
Sogroya has no boxed warning. Most of its warnings are drawn from experience with daily somatropin (Sogroya label).
Common side effects in adults
Adverse reactions in over 2% of adults and at least 1 percentage point more often than placebo, over 34 weeks (Sogroya label):
| Reaction | Somapacitan (n=120) | Placebo (n=61) |
|---|---|---|
| Back pain | 10% | 3.3% |
| Joint pain (arthralgia) | 6.7% | 1.6% |
| Indigestion (dyspepsia) | 5% | 3.3% |
| Sleep disorder | 4.2% | 1.6% |
| Dizziness | 4.2% | 1.6% |
| Peripheral edema (swelling) | 3.3% | 1.6% |
| Adrenal insufficiency | 3.3% | 1.6% |
| High blood pressure | 3.3% | 1.6% |
| Weight increase | 3.3% | 0% |
| Anemia | 2.5% | 0% |
More somapacitan users moved from normal to high phosphate (17.5% vs 4.9%) and creatine kinase (9.2% vs 6.6%). These changes were intermittent and did not progress. In REAL 1, injection-site reactions occurred in 6.7% on somapacitan, 5.9% on daily GH and 9.8% on placebo, and serious adverse events in 5.8%, 9.2% and 8.2% (Johannsson et al., JCEM 2020).
In children with GH deficiency, the most common reactions were nasopharyngitis (16.7% vs 16.2% on daily GH), headache (12.1% vs 8.8%), fever (9.1% vs 11.8%) and pain in the arms or legs (9.8% vs 2.9%) (Sogroya label).
Glucose and diabetes
The label warns that GH can lower insulin sensitivity, especially at higher doses, and that new type 2 diabetes has been reported with somatropin. It advises periodic glucose checks. A post hoc analysis of three adult phase 3 trials found no new cases of diabetes with somapacitan. Among untreated patients, fasting glucose, insulin and insulin resistance (HOMA-IR) rose more with daily GH than with somapacitan at 34 weeks, but not at 86 weeks. HbA1c did not differ (Takahashi et al., Pituitary 2023). This analysis was sponsored by the manufacturer.
Other labeled warnings
- Increased deaths in acute critical illness. Higher mortality has been reported with somatropin after open-heart or abdominal surgery, multiple trauma, or acute respiratory failure. These are contraindications.
- Tumors. Risk of progression with active cancer; second tumors (mostly meningiomas) in childhood cancer survivors treated with head radiation; watch existing moles for change.
- Intracranial hypertension (raised pressure around the brain), with headache, vision changes and papilledema (swelling of the optic disc), usually in the first 8 weeks.
- Fluid retention, including edema and carpal tunnel symptoms, usually transient and dose-dependent.
- Unmasked adrenal or thyroid deficiency. Cortisol may fall and thyroid function may worsen after starting GH, so glucocorticoid or thyroid doses may need to rise.
- In children: slipped capital femoral epiphysis (a hip growth-plate slip), worsening of existing scoliosis, and pancreatitis.
- Severe allergic reactions, including anaphylaxis and angioedema (reported with somatropin).
- Lipohypertrophy or lipoatrophy (fat lumps or dents) if the same site is used repeatedly.
Overdose may cause low then high blood sugar and fluid retention. Long-term overdose could cause signs of gigantism or acromegaly (Sogroya label).
Antibodies
No anti-somapacitan antibodies were found in the adult trials. In children with GH deficiency, 12.1% tested positive at some point during the first year, mostly at a single time point. No neutralizing antibodies were detected, and antibodies had no clinically significant effect (Sogroya label).
Interactions
| Drug | What happens |
|---|---|
| Glucocorticoid replacement (especially cortisone acetate, prednisone) | GH inhibits the enzyme that activates them; maintenance or stress doses may need to rise |
| Oral estrogen | Blunts the IGF-1 response; higher Sogroya doses may be needed |
| Insulin and other diabetes drugs | Doses may need adjustment because GH lowers insulin sensitivity |
| Drugs cleared by cytochrome P450 | GH may change their clearance; monitor |
Who should not use it
The label lists these contraindications (Sogroya label):
- acute critical illness after open-heart or abdominal surgery, multiple trauma, or acute respiratory failure;
- active malignancy;
- hypersensitivity to somapacitan or its ingredients;
- active proliferative or severe non-proliferative diabetic retinopathy;
- children with closed growth plates;
- children with Prader-Willi syndrome who are severely obese or have severe breathing problems.
No human pregnancy data exist for Sogroya. In rats and rabbits, it was not teratogenic at exposures about 12 times the maximum human dose (Sogroya label).
Monitoring
The label’s monitoring points:
| What | When |
|---|---|
| Fundoscopic eye exam | Before starting, then periodically |
| IGF-1 (adults) | 3–4 days after a dose, to guide titration; reduce dose if above the age- and sex-specific range |
| Blood glucose | Periodically, more closely with diabetes or risk factors |
| Thyroid function | Periodically |
| Cortisol / glucocorticoid needs | In patients with known or suspected adrenal insufficiency |
| Height velocity (children) | Ongoing; reassess if growth does not improve, especially in year 1 |
Legal status and use outside medicine
In the US, Sogroya is a prescription biologic. Its label states that it is not a controlled substance (Sogroya label).
In sport, the WADA Prohibited List bans GH and its analogs at all times, in and out of competition. Class S2.2.3 names somapacitan, lonapegsomatropin and somatrogon as examples of GH analogs (WADA 2026 Prohibited List).
All published efficacy trials of somapacitan enrolled people with GH deficiency or children with short stature. Healthy-volunteer studies have looked only at pharmacokinetics. There is no controlled evidence on muscle, strength, fat loss or recovery in people with normal GH levels, and its risks in that setting are those of GH excess.
Key takeaways
- Weekly GH, not a new hormone. Somapacitan is human GH with one amino acid change and an albumin-binding side chain, which stretches the adult half-life to about 2–3 days.
- Approved for deficiency and short stature. The FDA label covers adults with GH deficiency and children 2.5 years and older with GH deficiency, SGA, Noonan syndrome or ISS.
- Similar results to daily GH. In trials, growth in children and lean-mass and visceral-fat changes in adults were broadly similar to daily somatropin, with a smaller drop in truncal fat in adults.
- Dosing follows IGF-1. Adults start at 1.5 mg weekly (1 mg if over 65, 2 mg on oral estrogen) and titrate to a maximum of 8 mg, with IGF-1 drawn 3–4 days after a dose.
- Same class warnings as GH. These include glucose intolerance, fluid retention, joint pain, raised intracranial pressure and tumor concerns, and it is banned in sport under WADA S2.2.3.
Sources
- Novo Nordisk. Sogroya (somapacitan-beco) injection, prescribing information (revised 02/2026). DailyMed.
- US Food and Drug Administration. BLA 761156 approval letter, Sogroya (somapacitan-beco) injection. August 28, 2020. FDA.
- US Food and Drug Administration. BLA 761156/S-005 supplement approval letter, Sogroya (somapacitan-beco). April 28, 2023. FDA.
- European Medicines Agency. Sogroya (somapacitan): EPAR. EMA.
- Johannsson G, Gordon MB, Højby Rasmussen M, et al. Once-weekly somapacitan is effective and well tolerated in adults with GH deficiency: a randomized phase 3 trial. J Clin Endocrinol Metab. 2020;105(4):e1358–e1376. PubMed.
- Miller BS, Blair JC, Rasmussen MH, et al. Weekly somapacitan is effective and well tolerated in children with GH deficiency: the randomized phase 3 REAL4 trial. J Clin Endocrinol Metab. 2022;107(12):3378–3388. PubMed.
- Mauras N, Boettcher C, Højby M, et al. Once-weekly somapacitan enhances linear growth in girls with Turner syndrome: a randomized controlled phase 3 study. J Clin Endocrinol Metab. Published online August 1, 2026. doi:10.1210/clinem/dgag309. PubMed.
- Azhar S, Daniyal M, Memon RR, et al. Once-weekly somapacitan vs. daily norditropin in GHD: a systematic review and meta-analysis of efficacy and safety in children and adults. Endocrine. 2026;91(1):177. PubMed.
- Takahashi Y, Biller BMK, Fukuoka H, et al. Weekly somapacitan had no adverse effects on glucose metabolism in adults with growth hormone deficiency. Pituitary. 2023;26(1):57–72. PubMed.
- Helleberg H, Bjelke M, Damholt BB, et al. Absorption, metabolism and excretion of once-weekly somapacitan, a long-acting growth hormone derivative, after single subcutaneous dosing in human subjects. Eur J Pharm Sci. 2021;167:106030. PubMed.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026. WADA.