Structural and analytical reference
A laboratory identity reference comparing ipamorelin and sermorelin by residue count, structural family, terminal chemistry and analytical evidence.
Ipamorelin is a five-residue synthetic secretagogue. Sermorelin is the amidated GHRH/GRF(1–29) peptide. They have different sequences and structural classes, even when discussed in the same research literature.
Compare the declared identities
| Attribute | Ipamorelin | Sermorelin |
|---|---|---|
| Design class | Synthetic pentapeptide secretagogue | GHRH/GRF(1–29) peptide |
| Residue count | 5 | 29 |
| Sequence description | Aib-His-D-2-Nal-D-Phe-Lys-NH2 | N-terminal 1–29 fragment of human GHRH, amidated |
| Terminal feature | C-terminal amide | C-terminal amide |
| Documentation concern | Nonstandard residues and stereochemistry | Exact fragment, terminal amide and supplied salt form |
GRF and GHRH are names encountered in the growth hormone-releasing factor/hormone literature. A shared research context does not make the two peptides the same molecule.
Why a shared amide is not equivalence
The C-terminal amide is one structural attribute. It does not erase a 24-residue difference in backbone length or the difference in residue composition. The expected mass must be based on the whole declared structure, not just a common terminal group.
For ipamorelin, shorthand that drops Aib or the D-residue designations loses relevant identity information. For sermorelin, an unmodified fragment label must still specify the terminal form. A salt name such as acetate addresses a different layer of composition.
Molecular mass and salt form
A molecular-weight number can describe a neutral peptide, a salt representation or an analytical ion, depending on the record. Average molecular mass and monoisotopic mass also use different conventions. Compare like with like before treating numerical agreement as identity evidence.
A weighed powder can include counterions and residual moisture. A pure-looking chromatogram does not establish that every milligram of powder is peptide. The supplied material’s composition and quantitative assay basis should be declared separately.
A documentation checklist
- Full peptide identity, fragment boundaries and terminal groups.
- Counterion declaration and the basis of any content measurement.
- Lot and sample identifiers consistent across the record.
- Mass assignment and suitable chromatographic evidence for the actual sample.
Historical regulated-product documents are useful for identifying sermorelin chemistry. They do not certify an unrelated research material or authorize a different supplier’s product for clinical use. A research comparison remains an analytical reference, not a treatment selection guide.
Frequently asked questions
Is sermorelin another name for ipamorelin?
No. They are different peptide identities with 29- and five-residue backbones, respectively.
Is sermorelin the same as modified GRF(1–29)?
The same fragment length does not establish the same sequence. Check any substitutions and terminal chemistry explicitly.
Does an acetate label mean an N-acetyl peptide?
No. An acetate counterion and a covalently attached acetyl group are different chemical features.
Continue learning
Sources and scope
- Raun et al. (1998), ipamorelin discovery. Primary sequence and receptor-class reference; no dosing guidance is reproduced here.
- FDA historical Geref chemistry documentation. Identifies sermorelin as GRF(1–29)-NH2; a regulated formulation reference, not documentation for an SRL vial.
This original SRL reference uses the linked scientific and labeling records for molecular or analytical context. It does not reproduce an experimental protocol or certify a supplier batch. Prepared October 2, 2026.
