Peptide Basics
Growth Hormone Peptides: GHRH Analogues, GHRPs and How They Differ From HGH
Growth hormone peptides are peptides that make the pituitary gland release its own growth hormone; they are not growth hormone itself. They come in two groups, set by the receptor they act on: copies of the hypothalamic hormone GHRH (sermorelin, tesamorelin, CJC-1295) and agonists of the ghrelin receptor (ipamorelin, GHRP-2, GHRP-6, hexarelin). This page sets out the body’s own growth hormone system, what each of the seven peptides is chemically, which two non-peptides get listed with them, and where each one stands with FDA and the anti-doping rules. Every figure is taken from U.S. labels, FDA records, UniProt, PubChem or the dated records each compound guide cites.
Growth hormone vs growth hormone peptides
Growth hormone, also called somatotropin or HGH, is one of the peptide hormones, but at 191 amino acids and about 22,000 daltons it is protein-sized. The approved medicine, somatropin, is made by recombinant DNA technology and its U.S. label states that its sequence is identical to growth hormone of pituitary origin.
“Growth hormone peptides” are something else: short peptides, 5 to 44 amino acids long, that act one step upstream. They do not replace growth hormone; they signal the pituitary to release more of its own. Scientists call them growth hormone secretagogues, substances that cause growth hormone to be secreted.
The body’s own system: four peptides
Growth hormone release is set by two signals that switch it on and one that switches it off. GHRH acts on the GHRH receptor of the pituitary, ghrelin on the growth hormone secretagogue receptor (GHS-R1a), and somatostatin holds both back. Every growth hormone peptide copies one of the two “on” signals. Shortest to longest, with the lengths UniProt gives for the human mature peptides:
| Peptide | Amino acids | Made in | Role |
|---|---|---|---|
| Somatostatin-14 | 14 | Hypothalamus and gut | The brake: switches growth hormone release off. A longer form, somatostatin-28, is cut from the same precursor. |
| Ghrelin | 28 | Mainly the stomach | Acts on the ghrelin receptor (GHS-R1a). Its third amino acid, a serine, carries a fatty acid. |
| GHRH (growth hormone-releasing hormone) | 44 | Hypothalamus | Acts on the GHRH receptor of the pituitary. Ends in a leucine amide. |
| Growth hormone (somatotropin) | 191 | Anterior pituitary | The hormone itself. Protein-sized, about 22,000 daltons. |
Sources: UniProt P61278 (somatostatin), Q9UBU3 (ghrelin), P01286 (GHRH), P01241 (somatotropin), Q02643 (GHRH receptor, 423 amino acids) and Q92847 (GHS-R1a, 366); NORDITROPIN label via openFDA. Read 2 November 2026.
Group 1: GHRH analogues
These peptides copy GHRH, all or part of it, and bind the GHRH receptor. The first 29 of its 44 amino acids are enough to act, which is why two of the three are built on that fragment. Natural GHRH is broken down within minutes; each analogue is an attempt to make it last.
| Peptide | Amino acids | What it is |
|---|---|---|
| Sermorelin | 29 | The first 29 amino acids of human GHRH, with a C-terminal amide. Approved by FDA as Geref in 1990 and 1997; every Geref product is now discontinued. |
| Tesamorelin | 44 | All 44 amino acids of human GHRH, with a trans-3-hexenoyl group on the first tyrosine. FDA-approved since 2010 as Egrifta, now Egrifta SV. |
| CJC-1295 | 29 + linker | GHRH(1-29) with four amino acids replaced. The form with DAC carries a reactive lysine that bonds to albumin in the blood; the form without DAC is sold as Mod GRF 1-29. No FDA approval. |
The Egrifta SV label states that tesamorelin binds and stimulates human GHRH receptors with potency similar to the body’s own hormone. At 44 amino acids, tesamorelin is now held by FDA as a biologics licence (BLA 022505) rather than a drug application: since 2020, U.S. rules treat a chain of more than 40 amino acids as a protein, a line our peptide vs protein page explains.
Sources: PubChem CID 16132413 (sermorelin) and 16137828 (tesamorelin); EGRIFTA SV label via openFDA (2026-07-29); Drugs@FDA BLA022505, NDA019863, NDA020443; PMID 15817669 and 16352683 via the CJC-1295 guide. Read 17 October to 2 November 2026.
Group 2: ghrelin-receptor agonists (GHRPs)
The second group are the growth hormone-releasing peptides, or GHRPs: synthetic chains of five or six amino acids, several of them in the mirror-image D form, that bind GHS-R1a. They were made before ghrelin was discovered in 1999, which is why the receptor is named after them rather than after the hormone. In each sequence below, NH2 marks the amide at the end of the chain and the figure in brackets is PubChem’s molecular weight.
| Peptide | Amino acids | What it is |
|---|---|---|
| Ipamorelin | 5 | Aib-His-D-2-Nal-D-Phe-Lys-NH2 (711.9). No FDA approval. |
| GHRP-2 (pralmorelin) | 6 | D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2 (818.0). No FDA approval. |
| GHRP-6 | 6 | His-Trp-Ala-Trp-Phe-Lys-NH2 (873.0). No FDA approval. |
| Hexarelin (examorelin) | 6 | His-D-2-methyl-Trp-Ala-Trp-D-Phe-Lys-NH2 (887.0). No FDA approval. |
Two ghrelin-receptor agonists that are not peptides. Macimorelin (Macrilen) is a small synthetic molecule taken by mouth; FDA approved it on 20 December 2017 to diagnose adult growth hormone deficiency, and Drugs@FDA now lists it as discontinued. Ibutamoren, sold as MK-677, appears in many lists of growth hormone peptides, but PubChem records it as a small molecule (C27H36N4O5S, 528.7) and Drugs@FDA lists no approval for it.
Sources: PubChem CID 9831659, 6918245, 4345065, 6918297, 9804938 and 178024; MACRILEN label via openFDA (2021-01-30); Drugs@FDA NDA205598. Read 2 November 2026.
Where each one stands with FDA and WADA
From the dated regulatory record in each compound guide. “503A” and “503B” are FDA’s two compounding routes; our peptide legality page explains what each category means.
| Peptide | FDA approval | Compounding record | WADA 2026 |
|---|---|---|---|
| Sermorelin | Approved 1990 and 1997 as Geref; all products discontinued | Not on the 503A category lists | S2.2.4 |
| Tesamorelin | Approved since 2010 (Egrifta, Egrifta SV) | Not on the 503A category lists | S2.2.4 |
| CJC-1295 | No approval | Advisory committee voted against the 503A list, Dec 2024 | S2.2.4 |
| Ipamorelin | No approval | Advisory committee voted against the 503A list, Oct 2024; 503B Category 2 (significant safety risks), Sep 2023 | S2.2.4 |
| GHRP-2 | No approval | 503A Category 3; 503B Category 2, Sep 2023 | S2.2.4 |
| GHRP-6 | No approval | 503A Category 3; 503B Category 2, Sep 2023 | S2.2.4 |
| Hexarelin | No approval | Not on the 503A category lists or the 503B safety-risk page | S2.2.4 |
Sources: Drugs@FDA; FDA 503A category lists (updated 14 May 2026); FDA compounding safety-risk page (22 April 2026); FDA Pharmacy Compounding Advisory Committee minutes, 29 October and 4 December 2024; WADA 2026 Prohibited List, class S2.2.4 (banned at all times). Read 17 to 20 October 2026.
Growth hormone peptides sold for research
Search results for “growth hormone peptides” are mostly clinics and sellers. Six of the seven peptides on this page have no current FDA approval, and a product sold for research use only is labelled not for human use. Our pages on what research peptides are and sermorelin vs ipamorelin go further, and each guide sets out one compound’s identity, research history and regulatory record.
Medibact does not manufacture or sell peptides. We supply USP-grade bacteriostatic water, made in the USA, for research use only, and publish reference material like this page.
Where this sits in the rest of the reference
FAQ
What are growth hormone peptides?
The phrase usually means peptides that make the pituitary gland release its own growth hormone, not growth hormone itself. They fall into two groups by the receptor they act on: analogues of growth hormone-releasing hormone (GHRH), such as sermorelin, tesamorelin and CJC-1295, and agonists of the ghrelin receptor, such as ipamorelin, GHRP-2, GHRP-6 and hexarelin. Of these seven, only tesamorelin is an FDA-approved medicine today.
Is growth hormone a peptide?
Growth hormone is a single chain of 191 amino acids, about 22,000 daltons, so it is usually called a protein, although MeSH files it under the peptide hormones. The approved medicine, somatropin, has a sequence identical to pituitary growth hormone and is made by recombinant DNA technology. The secretagogue peptides are much smaller: 5 to 44 amino acids.
What is the difference between a GHRH analogue and a GHRP?
They act on different receptors. A GHRH analogue copies the hypothalamic hormone GHRH and binds the GHRH receptor on the pituitary. A growth hormone-releasing peptide (GHRP) binds the growth hormone secretagogue receptor, GHS-R1a, whose natural ligand is the stomach hormone ghrelin. Both routes end in growth hormone release from the same pituitary cells.
Which growth hormone peptides are FDA-approved?
Tesamorelin, as Egrifta SV, is the only one of the seven on this page with a current FDA approval; its label covers the reduction of excess abdominal fat in adults with HIV and lipodystrophy. Sermorelin was approved as Geref in 1990 and 1997, but every Geref product is now listed as discontinued. Macimorelin (Macrilen), an oral ghrelin-receptor agonist approved in 2017 to diagnose adult growth hormone deficiency, is a small molecule rather than a peptide and is also listed as discontinued.
Is MK-677 a peptide?
No. MK-677, ibutamoren, is often listed with growth hormone peptides because it also acts on the ghrelin receptor, but PubChem records it as a small molecule, C27H36N4O5S, with a molecular weight of 528.7. Drugs@FDA lists no approval for it.
What does ghrelin have to do with growth hormone?
Ghrelin is a 28-amino-acid hormone made mainly in the stomach, and it is the natural ligand of the growth hormone secretagogue receptor. The synthetic GHRPs were made before ghrelin was found, which is why the receptor carries the name of the drugs rather than the hormone. UniProt records that ghrelin's third amino acid, a serine, carries a fatty acid: an octanoyl, hexanoyl or decanoyl group.
Why do CJC-1295 and tesamorelin last longer than natural GHRH?
Both are built to resist the enzymes that break GHRH down. Tesamorelin carries a hexenoyl group on its first amino acid. CJC-1295 has four amino acids replaced, and its DAC form bonds to albumin in the blood; the human pharmacokinetic study of that form (PMID 16352683) measured a half-life of 5.8 to 8.1 days. Our sermorelin vs ipamorelin page sets out the published half-life figures for those two.
Are growth hormone peptides banned in sport?
Yes. Class S2.2.4 of the World Anti-Doping Agency's 2026 Prohibited List names all seven peptides on this page — sermorelin, tesamorelin, CJC-1295, ipamorelin, GHRP-2, GHRP-6 and hexarelin — and bans them at all times, in and out of competition.
Is this medical advice?
No. This page explains what growth hormone peptides are, from public scientific and regulatory sources. It gives no dose, schedule, protocol or recommendation, and peptides sold for research are labelled research use only, not for human use. Medibact supplies USP-grade bacteriostatic water, made in the USA, and is not affiliated with any manufacturer of the products named here.
References: UniProt P01241, P01286, Q9UBU3, P61278, Q02643, Q92847; PubChem CID 9831659, 6918245, 4345065, 6918297, 16132413, 16137828, 9804938, 178024; U.S. labels via openFDA for EGRIFTA SV, MACRILEN and NORDITROPIN; Drugs@FDA; FDA compounding records; WADA 2026 Prohibited List; PubMed 15817669, 16352683. Read 17 October to 2 November 2026.
Educational use only — not medical advice. This guide summarizes information reported in published research and community practice for educational purposes. It is not medical advice and not a recommendation to use any compound. Any doses, schedules, or combinations shown are examples of what has been reported, not instructions for you. Many peptides described here are research compounds that are not FDA-approved for the uses discussed and may be investigational or restricted. Effects, risks, and legal status vary; individual needs and results vary. Consult a qualified, licensed healthcare professional before making any decision. Do not use this content to diagnose, treat, or dose yourself.