Lonapegsomatropin
Lonapegsomatropin is an FDA-approved long-acting growth hormone prodrug. Lonapegsomatropin consists of unmodified somatropin bound to a methoxy polyethylene glycol carrier through a cleavable TransCon linker. The linker hydrolyses at physiological pH and temperature at a predictable rate, releasing native growth hormone continuously over the dosing week.
For research use only.
Key Facts
- CAS
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- Molecular Weight (MW)
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- Half-life
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- FDA status
- Approved
- Administration Route
- subcutaneous
- Frequency
- —
- Last updated
- Aug 30, 2026
- Reviewed
- Aug 30, 2026
Research summary
Once-weekly prodrug of somatropin approved for paediatric growth hormone deficiency, designed to release unmodified growth hormone rather than to act as a modified analog.
Peptide Library's Lonapegsomatropin profile summarises 5 cited studies listed in the Science section, the compound's regulatory status, and research-protocol parameters reported for it. It is a research reference, not medical advice.
Protocol
- Dosage Range
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- Frequency
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- Cycle
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- Administration Route
- subcutaneous
- Reconstitution Guide
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Science
Mechanism of Action
Lonapegsomatropin consists of unmodified somatropin bound to a methoxy polyethylene glycol carrier through a cleavable TransCon linker. The linker hydrolyses at physiological pH and temperature at a predictable rate, releasing native growth hormone continuously over the dosing week. Because the released hormone is structurally unmodified, its receptor interaction and tissue distribution match endogenous growth hormone.
Studies
- Efficacy and Safety of Somapacitan Relative to Somatrogon and Lonapegsomatropin in Pediatric Growth Hormone Deficiency: Systematic Literature Review and Network Meta-analysis
- Navepegritide combined with lonapegsomatropin for the treatment of children with achondroplasia: 52-week results from the phase 2 COACH trial
- Efficacy and Safety of Once-Weekly Lonapegsomatropin in Adults With Growth Hormone Deficiency: foresiGHt Trial Results
- Weekly Lonapegsomatropin in Treatment-Naïve Children With Growth Hormone Deficiency: The Phase 3 heiGHt Trial
- Children with Growth Hormone Deficiency Treated with Lonapegsomatropin Demonstrated Sustained Height Improvements for up to 6 Years: enliGHten Trial Final Results
Regulatory & research status
Lonapegsomatropin is an FDA-approved product for specific labelled indications. Approval does not extend to the research contexts described on this page, and approved products are prescription medicines.
| FDA status | Approved |
|---|---|
| Research status | Approved product (see FDA status) |
| Availability | Prescription-Only |
| WADA (sport) | Unknown / Not Listed |
| Library classification | FDA-Approved |
Benefits
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Potential Side Effects
No side effects listed yet for this entry.
Storage & stability
Lyophilized (freeze-dried) peptide powder is far more stable than the reconstituted solution. Keep sealed vials cold, dry and away from light; long-term storage is typically frozen, with short-term refrigeration for vials in use.
Once reconstituted in bacteriostatic water, keep the solution refrigerated, avoid repeated freeze–thaw cycles and agitation, and label the vial with the reconstitution date and concentration. Discard any solution that turns cloudy or shows particulates.
Degradation rates differ by sequence: peptides containing methionine, cysteine, asparagine or glutamine are more prone to oxidation and deamidation, so shelf life after reconstitution is compound-specific rather than universal.
Read the full guide: how to store peptides before and after reconstitution →
Source: Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Stability of protein pharmaceuticals: an update. Pharm Res. 2010;27(4):544–575. (PMID 20143256). General guidance for research handling; not product-specific instructions.
Lonapegsomatropin: frequently asked questions
What is Lonapegsomatropin?
Once-weekly prodrug of somatropin approved for paediatric growth hormone deficiency, designed to release unmodified growth hormone rather than to act as a modified analog.
How does Lonapegsomatropin work?
Lonapegsomatropin consists of unmodified somatropin bound to a methoxy polyethylene glycol carrier through a cleavable TransCon linker. The linker hydrolyses at physiological pH and temperature at a predictable rate, releasing native growth hormone continuously over the dosing week.
Is Lonapegsomatropin FDA approved?
Yes. Lonapegsomatropin is approved by the FDA, and approved products are prescription medicines. Approval is always for specific indications studied in clinical trials, so an approved status does not mean the compound is approved for every use it is discussed for. Research-chemical material sold under the same name is not the approved product.
What peptides are similar to Lonapegsomatropin?
Compounds most often compared with Lonapegsomatropin include Human Growth Hormone (Somatropin), Somapacitan, Somatrogon and Pegvisomant. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ.
References
- Efficacy and Safety of Somapacitan Relative to Somatrogon and Lonapegsomatropin in Pediatric Growth Hormone Deficiency: Systematic Literature Review and Network Meta-analysis — Adv Ther, 2024External reference
- Navepegritide combined with lonapegsomatropin for the treatment of children with achondroplasia: 52-week results from the phase 2 COACH trial — Eur J Endocrinol, 2026External reference
- Efficacy and Safety of Once-Weekly Lonapegsomatropin in Adults With Growth Hormone Deficiency: foresiGHt Trial Results — J Clin Endocrinol Metab, 2026External reference
- Weekly Lonapegsomatropin in Treatment-Naïve Children With Growth Hormone Deficiency: The Phase 3 heiGHt Trial — J Clin Endocrinol Metab, 2021External reference
- Children with Growth Hormone Deficiency Treated with Lonapegsomatropin Demonstrated Sustained Height Improvements for up to 6 Years: enliGHten Trial Final Results — Horm Res Paediatr, 2026External reference
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Compiled by Peptide Library Editorial · Reviewed Aug 30, 2026 · Updated Aug 30, 2026 · Version 1
This Lonapegsomatropin profile is compiled from published literature (5 cited studies linked above), public regulatory records and chemical registries. It describes what research reports; it is not medical advice, and nothing here is a dosing recommendation for humans. Peptide Library does not sell peptides. Editorial policy · How profiles are compiled · Report an error
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