Compound Notes · Jul 28, 2026
Ipamorelin vs Tesamorelin: Different Receptors, Seven Times the Size
Of all the pairs in this catalogue, this is the one with the least in common.
Two different receptor families
Ipamorelin acts at the growth hormone secretagogue receptor (GHS-R), the GHRP family.
Tesamorelin is an analogue of growth hormone releasing hormone, acting at the GHRH receptor.
Different receptors, different families, different design lineage. They appear together in the literature because both relate to growth hormone regulation, not because they are alternatives.
The size gap is the largest in this catalogue
| Ipamorelin | Tesamorelin | |
|---|---|---|
| Molecular formula | C38H49N9O5 | C221H366N72O67S |
| Molar mass | 711.86 g/mol | 5,135.87 g/mol |
| CAS | 170851-70-4 | 218949-48-5 |
| Sulfur | none | yes |
Tesamorelin is about 7.2 times heavier. Ipamorelin is a pentapeptide, five residues, one of the shortest and most reliably synthesised compounds anyone sells. Tesamorelin is a long chain with a sulfur-containing residue.
What that means for judging a supplier
For ipamorelin, high purity is close to expected. Five coupling steps do not leave much room for error, so a 99% figure tells you relatively little about a supplier's capability.
For tesamorelin, purity is genuinely informative. A long chain accumulates deletion sequences, and separating them requires real purification work. This is where a certificate with a chromatogram and a stated method earns its place, and where a bare number should not be trusted.
Tesamorelin's sulfur adds oxidation as a degradation route ipamorelin does not have, so it is the more demanding of the two to store: dark, minimal headspace, and a shorter working window in solution.
Testing status
Neither has an analysed lot at present. Current status per lot is on the lab results page.
Related
Supplied as laboratory reagents for research use only. Not approved by Health Canada for human or veterinary use.
Compounds covered here
- TesamorelinOut of stock
- IpamorelinOut of stock
Supplied as a laboratory reagent for research use only. Not for human or veterinary use.
Related reading
- Peptide Comparisons: The Full Index
Every side-by-side in one place, grouped by what the compounds actually have in common: receptor family, molecule class, or nothing but a reputation for being similar.
- TB-500 vs GHK-Cu: The Largest and Smallest in the Catalogue
A 4,963 g/mol peptide against a 402 g/mol copper complex. A twelvefold size difference changes everything about how the two are made, priced and handled.
- Tesamorelin vs CJC-1295: Two GHRH Analogues, Very Different Sizes
Same receptor family, same design idea, and a 1,700 g/mol gap between them. What that gap means for synthesis, purity and price.
- Ipamorelin vs CJC-1295: Two Different Molecule Classes
One is a small pentapeptide, the other is nearly five times its size and works on a different receptor family entirely. The comparison people make most often is between two things that are not the same kind of thing.