Growth Hormone Secretagogues

Growth hormone secretagogues, GHRH analogs and hGH fragments, supplied as lyophilised powder for laboratory research use only. The compounds in this category act on the somatotropic axis, and they divide cleanly into two mechanistic groups that are constantly discussed as if they were one.

Two receptors, not one

GHRH analogs act at the growth hormone releasing hormone receptor. Sermorelin is GRF(1-29) amide — the first 29 residues of the native 44-residue hormone, C₁₄₉H₂₄₆N₄₄O₄₂S, about 3,357.9 g/mol, CAS 86168-78-7. CJC-1295 without DAC, also called Mod GRF(1-29), is the same fragment with four substitutions — [D-Ala2, Gln8, Ala15, Leu27] — each chosen to resist a specific degradation route. Tesamorelin is the full 44-residue sequence with a trans-3-hexenoyl group on the N-terminus.

Secretagogues act at the growth hormone secretagogue receptor GHSR-1a, a different receptor with a different signalling pathway. Ipamorelin is a pentapeptide, C₃₈H₄₉N₉O₅, about 711.9 g/mol, CAS 170851-70-4, and three of its five residues are non-standard.

Because the two groups engage different receptors, a study using one is not a study of the other, and combining them is a different experiment again rather than a stronger version of either. See GHRH analogs versus growth hormone secretagogues and Ipamorelin and GHSR-1a selectivity.

The DAC distinction, which is the commonest sourcing error

CJC-1295 exists in two forms that are routinely conflated. Without DAC it is C₁₅₂H₂₅₂N₄₄O₄₂ at about 3,367.9 g/mol, CAS 863288-34-0. With the drug affinity complex it is C₁₆₅H₂₆₉N₄₇O₄₆ at about 3,647.2 g/mol, CAS 446262-90-4 — a difference of roughly 280 Da and a completely different half-life profile. The mass on the certificate is what tells you which one you have. See what the DAC modification changes.

Fragments

AOD-9604 is a modified hGH(177-191) fragment with an added N-terminal tyrosine, C₇₈H₁₂₃N₂₃O₂₃S₂, about 1,815.1 g/mol, CAS 221231-10-3. A fragment of a hormone is not a low dose of that hormone; it is a distinct molecule with its own binding profile. See AOD-9604 and the hGH fragment.

Analysis and handling

Several compounds in this category contain non-standard or D-amino acids, which means amino-acid analysis after hydrolysis cannot confirm the sequence — identity rests on mass and on the synthesis route. Products are third-party tested for HPLC purity; certificates are published on product pages and on the certificates of analysis page, and vials are matched to their certificate by cap and crimp colour. See how HPLC and mass spectrometry verify purity and what sets a peptide’s half-life.

Supplied for laboratory research use only. Not approved by the FDA; not manufactured to pharmaceutical GMP standards; not for human or veterinary use.