Sermorelin vs Ipamorelin: Two Routes to Growth Hormone Release Compared

Sermorelin and ipamorelin are two of the most compared growth hormone research peptides, and the reason is simple: both cause the pituitary gland to release growth hormone (GH), but they get there through completely different receptors. Sermorelin is a shortened copy of the body’s own GH-releasing hormone (GHRH). Ipamorelin is a small synthetic peptide that acts on the ghrelin receptor. This guide compares their structure, receptors, published research and regulatory history side by side.

All compounds discussed are sold for laboratory research use only. This page summarizes published research and is not guidance for human or veterinary use.

At a glance

Two different routes to the same hormone

GH release from the pituitary is controlled by more than one signal. GHRH from the hypothalamus switches it on, somatostatin switches it off, and ghrelin, a hormone made mostly in the stomach, adds a third input through its own receptor. Sermorelin and ipamorelin each copy one of the “on” signals.

• Sermorelin binds the GHRH receptor, the same receptor the body’s own GHRH uses. Its activity depends on that pathway working normally.
• Ipamorelin binds the ghrelin receptor, first identified in the pituitary and hypothalamus as the target of synthetic GH-releasing peptides (Howard et al., 1996).

Because they use different receptors, the two pathways can act at the same time. Early human studies with the GH-releasing peptide GHRP-6 found that it and GHRH released GH synergistically when given together, and the authors concluded the two act independently (Bowers et al., 1990). That finding is why GHRH analogs and ghrelin-receptor agonists are often studied as a pair.

Sermorelin: a shortened copy of natural GHRH

Human GHRH is a 44-residue peptide, isolated and sequenced in the early 1980s (Ling et al., 1984; Thorner, 2008). Researchers found that the first 29 residues carry the full activity at the receptor, and that fragment, with an amide at the end, is sermorelin. Its receptor was later cloned and characterized in pituitary cells (Mayo, 1992).

Sermorelin was developed into an FDA-approved product called Geref, used for diagnosing and treating growth hormone deficiency in children (Prakash and Goa, 1999). The manufacturer discontinued it in 2008, and in 2013 the FDA formally determined that it was not withdrawn for reasons of safety or effectiveness. The material sold for research is a reagent, not that drug product. See the sermorelin research overview.

Ipamorelin: a selective ghrelin-receptor agonist

Ipamorelin came out of Novo Nordisk’s work on growth hormone secretagogues in the 1990s. Its defining paper described it as the first selective GH secretagogue: in animal studies it released GH at a potency similar to GHRP-6, but unlike older secretagogues it did not significantly raise ACTH or cortisol, even at doses well above those needed for GH release (Raun et al., 1998).

In rats, ipamorelin increased longitudinal bone growth (Johansen et al., 1999). In healthy human volunteers, a pharmacokinetic study measured a terminal half-life of about 2 hours and a single GH peak after each infusion (Gobburu et al., 1999). Its only published Phase II trial tested it for a different purpose, recovery of gut function after bowel surgery, and found no statistically significant difference from placebo (Beck et al., 2014). It has never been approved as a drug. See the ipamorelin research overview.

Where their research overlaps

• Same end point: both are studied for their effect on GH release from the pituitary, and on IGF-1 downstream of it.
• Both are short-acting: neither has a built-in mechanism to extend circulation, unlike CJC-1295 with DAC. See CJC-1295 with DAC vs without DAC.
• Same anti-doping category: GHRH analogs and GH secretagogues are both on the WADA Prohibited List.

How researchers choose between them

• Studying the GHRH pathway: sermorelin acts directly on the GHRH receptor and has the longer clinical history, including an approved product.
• Studying the ghrelin-receptor pathway: ipamorelin is the more selective tool, with published data showing GH release without the cortisol and ACTH changes seen with older secretagogues.
• Studying both pathways together: because the two receptors act independently, many study designs pair a GHRH analog with a ghrelin-receptor agonist. The most common pairing uses CJC-1295 without DAC; see the CJC-1295 and ipamorelin research overview.
• Comparing GHRH analogs: for how sermorelin stacks up against longer-acting GHRH analogs, see Sermorelin vs CJC-1295 vs Tesamorelin.

What the research does not show

Sermorelin’s clinical data comes mostly from pediatric growth hormone deficiency, and the approved product was discontinued years ago. Ipamorelin’s human data is limited to small pharmacokinetic studies and one Phase II trial that did not meet its goal. There are no head-to-head studies comparing the two, and no long-term safety data for either in healthy adults. Much of what circulates online comparing them is anecdotal rather than published. Neither compound’s research supports any use outside a laboratory.

Verify what you’re working with

At roughly 3,358 and 712 g/mol, sermorelin and ipamorelin are easy to tell apart by mass spectrometry, which is how identity testing confirms what is in a vial. Every Rogue batch is tested by an independent, ISO 17025 accredited U.S. lab, and the QR code on each vial opens that batch’s report on the lab’s own website. See how to read a peptide COA or browse the COA Library.

View Sermorelin on Rogue Compounds

View Ipamorelin on Rogue Compounds

References

1. Ling N, Esch F, Böhlen P, et al. Isolation, primary structure, and synthesis of human hypothalamic somatocrinin: growth hormone-releasing factor. Proc Natl Acad Sci U S A. 1984;81(14):4302-4306. PMID 6431406
2. Thorner MO. The discovery of growth hormone-releasing hormone: an update. J Neuroendocrinol. 2008;20(6):653-654. PMID 18601685
3. 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
4. Prakash A, Goa KL. Sermorelin: a review of its use in the diagnosis and treatment of children with idiopathic growth hormone deficiency. BioDrugs. 1999;12(2):139-157. PMID 18031173
5. U.S. Food and Drug Administration. Determination that GEREF (sermorelin acetate) injection products were not withdrawn from sale for reasons of safety or effectiveness. Federal Register. March 4, 2013. Notice 2013-04827
6. Howard AD, Feighner SD, Cully DF, et al. A receptor in pituitary and hypothalamus that functions in growth hormone release. Science. 1996;273(5277):974-977. PMID 8688086
7. Bowers CY, Reynolds GA, Durham D, et al. Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. J Clin Endocrinol Metab. 1990;70(4):975-982. PMID 2108187
8. Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561. PMID 9849822
9. Johansen PB, Nowak J, Skjaerbaek C, et al. Ipamorelin, a new growth-hormone-releasing peptide, induces longitudinal bone growth in rats. Growth Horm IGF Res. 1999;9(2):106-113. PMID 10373343
10. Gobburu JV, Agersø H, Jusko WJ, Ynddal L. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharm Res. 1999;16(9):1412-1416. PMID 10496658
11. Beck DE, Sweeney WB, McCarter MD. Prospective, randomized, controlled, proof-of-concept study of the ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients. Int J Colorectal Dis. 2014;29(12):1527-1534. PMID 25331030