Sermorelin — GHRH(1-29)NH2 | 29-Amino Acid Growth Hormone-Releasing Hormone Analog
Research-Grade Compound
Sermorelin is a synthetic 29-amino-acid peptide corresponding to the biologically active N-terminal fragment of growth hormone-releasing hormone, formally designated GHRH(1-29)NH2 or GRF(1-29)NH2. Molecular formula C149H246N44O42S, molecular weight 3,357.9 Da, CAS 86168-78-7.
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In-depth research overview, mechanism of action, and study applications.
This Certificate of Analysis was issued by an independent third-party laboratory. Peptide.Express does not conduct in-house testing. Results are provided as-is from the testing facility and confirm batch identity, purity, and analytical methodology. For questions about specific CoA results, contact [email protected].
What is Sermorelin?
Sermorelin is a synthetic 29-amino-acid peptide corresponding to the biologically active N-terminal fragment of growth hormone-releasing hormone, formally designated GHRH(1-29)NH2 or GRF(1-29)NH2. Molecular formula C149H246N44O42S, molecular weight 3,357.9 Da, CAS 86168-78-7.
The 1-29 truncation is not an approximation of GHRH — it is the functional core. Work through the 1980s established that the C-terminal residues of the 44-amino-acid hormone contribute little to receptor binding, and that the first 29 residues retain essentially full activity at GHRH-R. Sermorelin is what is left when you delete the part that does not do the binding. Everything about how it behaves at the receptor follows from that.
Sermorelin was the first GHRH analog to reach FDA approval, marketed as Geref for pediatric growth hormone deficiency and, in a separate formulation, as a diagnostic agent for pituitary function. Geref was withdrawn from the US market in 2008. The withdrawal is generally described as a commercial decision rather than a safety action, and no replacement approval followed. One consequence is that the sermorelin literature is old: most of the human pharmacology dates from the late 1980s and 1990s, and modern head-to-head comparisons against tesamorelin or CJC-1295 essentially do not exist. Researchers reading across between these compounds are comparing datasets separated by two decades of methodological change.
How Does Sermorelin Work? Mechanism of Action
Sermorelin binds GHRH-R on anterior pituitary somatotrophs — the same receptor engaged by endogenous GHRH, and the same receptor tesamorelin and CJC-1295 No DAC target. The receptor is a class B GPCR coupled to Gs. Binding activates adenylyl cyclase, cAMP rises, protein kinase A is activated, and PKA phosphorylates CREB while calcium influx through voltage-gated channels triggers exocytosis of stored GH granules.
The pulsatile character of the resulting GH release is the property researchers select sermorelin for. Somatostatin from the hypothalamus continues to oppose somatotroph firing as GH rises, so output arrives in pulses that track the endogenous rhythm rather than as a sustained elevation. Recombinant GH administration flattens that rhythm and suppresses the somatotroph. Whether pulse architecture matters for a given endpoint depends entirely on the model — but if it does, a GHRH analog is the only way to preserve it.
Sermorelin is the least stable of the three GHRH analogs in this catalog, and deliberately so — it carries no protective modification. Native GHRH is cleaved by dipeptidyl peptidase IV at the Ala2 position, and sermorelin, retaining that same N-terminal region unmodified, is cleaved the same way. Reported plasma half-life is on the order of 10 to 20 minutes. CJC-1295 No DAC substitutes four residues to slow that cleavage and roughly doubles the figure; tesamorelin caps the N-terminus outright. Sermorelin sits at the short end of the series, which makes it a useful negative control when the research variable is stability rather than receptor engagement.
A gap worth naming: the downstream IGF-1 response to sermorelin is less thoroughly characterised in modern assay conditions than tesamorelin's is. The direction of the effect is not in question — GHRH-R agonism raises GH, GH raises hepatic IGF-1 — but the quantitative literature is thinner and older. Protocols that need a defined IGF-1 dose-response should build one rather than assume one.
Research Applications of Sermorelin
GHRH Receptor Pharmacology
- Receptor-binding studies: as the minimal fully active GHRH fragment, sermorelin is the natural reference ligand for GHRH-R affinity and structure-activity work.
- cAMP accumulation assays: pituitary somatotroph and transfected-cell preparations give the proximal second-messenger readout without any GH measurement involved.
- Structure-activity comparison: running sermorelin against CJC-1295 No DAC isolates the contribution of the four stabilising substitutions, since the two share the same 29-residue backbone.
Somatotropic Axis and Pituitary Function Models
- Pituitary reserve assessment: sermorelin's original diagnostic role was probing somatotroph responsiveness, and that use survives in research models of pituitary function.
- Pulse-architecture studies: preserved somatostatin counter-regulation makes sermorelin a tool for questions about GH pulse frequency and amplitude rather than total exposure.
- Age-related somatotropic decline: the axis becomes less responsive with age in animal models, and GHRH-R agonists are the standard probe for characterising where in the axis the change sits.
Comparative and Combination Design
- Half-life series: sermorelin, CJC-1295 No DAC and tesamorelin form a graded stability series at a single receptor, which is difficult to construct with any other peptide class.
- GHRH-R plus GHSR-1a co-stimulation: pairing sermorelin with ipamorelin activates two independent second-messenger systems converging on the same cell.
- Secretagogue versus direct GH arms: including a sermorelin arm alongside a recombinant GH arm separates receptor-mediated pulsatile signaling from GH exposure alone.
Sermorelin vs Tesamorelin
| Feature | Sermorelin | Tesamorelin |
|---|---|---|
| Identity | GHRH(1-29)NH2, unmodified active fragment | Full-length GHRH analog, N-terminally stabilized |
| Amino acid count | 29 | 44 |
| Molecular formula | C149H246N44O42S | C221H366N72O67S |
| Molecular weight | 3,357.9 Da | 5,135.9 Da |
| CAS number | 86168-78-7 | 218949-48-5 |
| Structural modification | None — C-terminal amide only | Trans-3-hexenoyl group at the N-terminus |
| Receptor target | GHRH-R | GHRH-R |
| Second messenger | cAMP-PKA | cAMP-PKA |
| Approximate plasma half-life | 10–20 minutes | Tens of minutes (per FDA label) |
| DPP-IV susceptibility | Cleaved at the Ala2 position | N-terminal cap blocks cleavage |
| FDA status | Approved as Geref; withdrawn from the market in 2008 | Approved as Egrifta, currently marketed |
| Human data vintage | Largely late 1980s and 1990s | Phase 3 program published 2008 onward |
| WADA status | Prohibited at all times | Prohibited at all times |
These two are the same pharmacology at different levels of engineering. Sermorelin is GHRH stripped to its active core and left unprotected; tesamorelin is the full hormone with a chemical guard on the cleavage site. If the research question is about GHRH-R itself, sermorelin is the cleaner ligand. If it is about producing a sustained downstream IGF-1 response, the stability difference dominates.
Sermorelin Technical Specifications
| Compound Name | Sermorelin |
|---|---|
| Designation | GHRH(1-29)NH2 | GRF(1-29)NH2 |
| Common Synonyms | Sermorelin acetate, GRF 1-29, Geref (withdrawn brand name) |
| Classification | Synthetic GHRH analog (N-terminal 1-29 fragment) |
| Receptor Target | GHRH-R (growth hormone-releasing hormone receptor) |
| CAS Number | 86168-78-7 |
| Molecular Formula | C149H246N44O42S |
| Molecular Weight | 3,357.9 Da |
| Amino Acid Count | 29 |
| Sequence Note | GRF(1-29) NH2 — 29-amino-acid GHRH analog with a C-terminal amide |
| Approximate Plasma Half-Life | 10–20 minutes (reported) |
| Purity | ≥99% by HPLC |
| Purity Confirmation | LC-MS/MS molecular weight verification |
| Endotoxin Testing | LAL (Limulus Amebocyte Lysate) method |
| Physical Form | Lyophilized powder |
| Appearance | White to off-white powder |
| Reconstitution | Bacteriostatic water or sterile 0.9% sodium chloride |
| Storage (lyophilized) | -20°C, desiccated, protected from light |
| Storage (reconstituted) | 2–8°C, use within 14–28 days |
| Shelf Life | 24 months from manufacture (lyophilized) |
| Testing Methods | HPLC, LC-MS/MS, LAL Endotoxin |
| Documentation | Certificate of Analysis (CoA) per batch |
| FDA Status | Prior approval as Geref; withdrawn from the US market in 2008. No current approval. |
| WADA Status | Prohibited at all times (growth hormone releasing factors) |
| Intended Use | In-vitro laboratory research only |
How to Reconstitute Sermorelin for Research
Sermorelin dissolves readily — at 3,357.9 Da it is a mid-sized peptide with good aqueous solubility and it rarely needs the full 90 seconds. The more common handling error with sermorelin is not dissolution but concentration arithmetic: 29-residue GHRH analogs are usually supplied in small vial masses, so a 1 mL versus 2 mL diluent choice changes the working concentration by a factor of two and is easy to lose track of across a batch of vials.
- Allow the vial to reach room temperature before opening.
- Draw the calculated volume of bacteriostatic water. For the 10 mg vial, 2 mL yields 5 mg/mL and 5 mL yields 2 mg/mL.
- Swab the septum with alcohol and allow 30 seconds to dry.
- Inject the diluent slowly against the inner vial wall rather than onto the lyophilized cake.
- Swirl gently until fully dissolved — usually 45–60 seconds for sermorelin. Do not shake or vortex.
- Inspect the solution. It should be clear and colorless with no particulate. Discard if cloudy or discolored.
- Label the vial with the reconstitution date and the resulting concentration in mg/mL.
- Store at 2–8°C and use within 14–28 days. Avoid repeated freeze-thaw cycles.
Diluent: bacteriostatic water for peptide reconstitution. Full protocol: step-by-step peptide reconstitution guide. Concentration maths: peptide reconstitution calculator.
Frequently Asked Questions — Sermorelin
What is sermorelin?
Is sermorelin the same as GHRH?
Is sermorelin the same as Geref?
What is the difference between sermorelin and tesamorelin?
What is the difference between sermorelin and CJC-1295?
Does sermorelin increase growth hormone?
What is sermorelin's half-life?
How does sermorelin work at the molecular level?
Why is the sermorelin research literature so old?
Is sermorelin WADA prohibited?
What purity standard does Peptide.Express use for sermorelin?
What testing does sermorelin undergo before shipping?
How should sermorelin be stored before and after reconstitution?
Where is the Certificate of Analysis for sermorelin?
Research References
- Prakash A, Goa KL. "Sermorelin: A Review of its Use in the Diagnosis and Treatment of Children with Idiopathic Growth Hormone Deficiency." BioDrugs, 1999. Read the sermorelin clinical review on PubMed
- Mayo KE. "Molecular Cloning and Expression of a Pituitary-Specific Receptor for Growth Hormone-Releasing Hormone." Molecular Endocrinology, 1992. Read the GHRH receptor cloning and cAMP-signaling study on PubMed
- Wehrenberg WB, Ling N. "In Vivo Biological Potency of Rat and Human Growth Hormone-Releasing Factor and Fragments of Human Growth Hormone-Releasing Factor." Biochemical and Biophysical Research Communications, 1983. Read the GRF fragment structure-activity study on PubMed
- For contrast, the tesamorelin clinical dataset is the closest thing to modern human pharmacology for any GHRH analog. Falutz J, et al. AIDS, 2008. Read the tesamorelin long-term safety study on PubMed
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