Sermorelin vs tesamorelin: two lengths of the same hormone
Sermorelin and tesamorelin are both built on the sequence of human growth-hormone-releasing hormone: sermorelin is its first 29 residues with a C-terminal amide, and tesamorelin is the full 44-residue sequence with an added N-terminal hexenoyl group.[1],[2]
Because both are recorded as agonists at the GHRH receptor, the comparison turns on length and N-terminal chemistry rather than on receptor target.[3],[2]
The page lays out the identity records, the enzyme-cleavage literature that explains the N-terminal change, and each compound's U.S. regulatory entry.
Identity side by side
| Attribute | Sermorelin | Tesamorelin |
|---|---|---|
| Also recorded as[3],[2] | GRF(1-29)NH2; hGRF(1-29); GHRH (1-29) amide | TH9507; trans-3-hexenoyl GHRH (1-44) amide |
| FDA UNII[1],[2] | 89243S03TE | MQG94M5EEO |
| CAS Registry Number[3],[2] | 86168-78-7 | 218949-48-5 |
| Length[1],[2] | 29 residues | 44 residues |
| Sequence (one-letter)[1],[2] | YADAIFTNSYRKVLGQLSARKLLQDIMSR | YADAIFTNSYRKVLGQLSARKLLQDIMSRQQGESNQERGARARL |
| N-terminus[1],[2] | Unmodified tyrosine | (3E)-3-hexenoyl group on tyrosine 1 |
| C-terminus[1],[2] | Argininamide (position 29) | Leucinamide (position 44) |
| Molecular formula[3],[2] | C149H246N44O42S | Not stated (registry figures omit the modification) |
| Receptor recorded[3],[2] | GHRH receptor | GHRH receptor |
| Dipeptidyl peptidase IV[4],[5] | GRF(1-29)NH2 cleaved to GRF(3-29)NH2 | Reported resistant to DPP-IV deactivation |
| U.S. regulatory entry[6],[7] | Drugs@FDA, NDA 019863 and NDA 020443 | Drugs@FDA, BLA 022505 |
How do the two sequences line up?
Laid against each other, the registry sequences agree across all 29 residues of sermorelin, and tesamorelin then continues for fifteen more, ending QQGESNQERGARARL.[1],[2]
Sermorelin closes with an amidated arginine at position 29, whereas tesamorelin closes with leucinamide at position 44.[1],[2]
The one addition tesamorelin makes to the human sequence is a trans-3-hexenoyl group on tyrosine 1, which the TH9507 nonclinical paper calls a minimal modification of hGRF1-44NH2.[5],[2]
What receptor and enzyme pathway do they share?
Both are recorded at the GHRH receptor, first cloned in 1992, which bound human GHRH with high affinity and raised cAMP when expressed in human kidney 293 cells.[3],[2],[8]
That receptor belongs to the secretin/glucagon/VIP subfamily, and in rat and human pituitary its immunoreactivity was confined to somatotropes.[9]
The two diverge at dipeptidyl peptidase IV: GRF(1-29)NH2 is degraded mainly by that enzyme in plasma to GRF(3-29)NH2, a product the source calls inactivated.[4]
TH9507 was reported to resist the same enzyme, and its N-terminal modification slowed in-vitro breakdown in rat, dog and human plasma relative to natural hGRF1-44NH2.[5]
What do the U.S. regulatory records say?
Both compounds have Drugs@FDA records, but the status recorded under each is different.[6],[7]
Drugs@FDA lists two approved applications for sermorelin acetate, and the products under both are listed as discontinued. PepGenex research materials are not those products, are not FDA approved, and are not for human or veterinary use. Source: Drugs@FDA, Applications NDA 019863 and NDA 020443. Checked 2026-09-24.
An FDA approved drug product containing tesamorelin exists. PepGenex research materials are not that product, are not FDA approved, and are not for human or veterinary use. Source: Drugs@FDA, Application BLA 022505. Checked 2026-09-24.
What does this comparison not establish?
The cleavage findings for the two molecules come from different laboratories and matrices, so as a set they describe a mechanism rather than a measured stability difference between them.[4],[5]
Clinical publications on each compound used different populations and endpoints, and they stay on the individual compound pages.
Limitations
The receptor statements describe the natural hormone's receptor; no receptor-binding measurement for tesamorelin itself is cited.[2]
The sermorelin structure-activity literature scanned a norleucine-substituted analogue rather than sermorelin itself, so it is not cited on this page.[10]
Compound profiles
References
- U.S. FDA Global Substance Registration System (GSRS), Sermorelin, UNII 89243S03TE. UNII 89243S03TE · CAS 86168-78-7
- Tesamorelin research profile, PepGenex Science (identity and records, with their sources).
- Sermorelin research profile, PepGenex Science (identity and records, with their sources).
- Bai JP, Chang LL. The involvement of dipeptidyl peptidase IV in brush-border degradation of GRF(1-29)NH2 by intestinal mucosal cells. J Pharm Pharmacol. 1995;47(8):698-701. PMID 8583376 · DOI 10.1111/j.2042-7158.1995.tb05863.x
- Ferdinandi ES, Brazeau P, High K, et al. Non-clinical pharmacology and safety evaluation of TH9507, a human growth hormone-releasing factor analogue. Basic Clin Pharmacol Toxicol. 2007;100(1):49-58. PMID 17214611 · DOI 10.1111/j.1742-7843.2007.00008.x
- Drugs@FDA, Applications NDA 019863 and NDA 020443. Checked 2026-09-24
- Drugs@FDA, Application BLA 022505. Checked 2026-09-24
- Mayo KE. Molecular cloning and expression of a pituitary-specific receptor for growth hormone-releasing hormone. Mol Endocrinol. 1992;6(10):1734-1744. PMID 1333056 · DOI 10.1210/mend.6.10.1333056
- Morel G, Gallego R, Boulanger L, Pintos E, Garcia-Caballero T, Gaudreau P. Restricted presence of the growth hormone-releasing hormone receptor to somatotropes in rat and human pituitaries. Neuroendocrinology 1999. PMID 10461027 · DOI 10.1159/000054467
- Cervini LA, Donaldson CJ, Koerber SC, Vale WW, Rivier JE.. Human growth hormone-releasing hormone hGHRH(1-29)-NH2: systematic structure-activity relationship studies.. Journal of Medicinal Chemistry 1998. PMID 9513600 · DOI 10.1021/jm970618s