RESEARCH MONOGRAPH · KDC-MN-079

Sermorelin

May 9, 2026 Kodiac biolabs Research Revised May 30, 2026 2 min read

Our opinion on this compound

75/100

First-generation GHRH analog, mechanism-perfect for restoring physiological GH pulsing, just short half-life

Sermorelin is GHRH 1-29 amide, the N-terminal 29 amino acid fragment of growth hormone-releasing hormone that retains full receptor agonist activity. Roger Guillemin and Wylie Vale at Salk characterized the parent GHRH in the late 70s, and the truncated active fragment became sermorelin (Geref) in the 80s and 90s as the first commercially viable GHRH analog.

What we like is honestly the mechanism elegance. Sermorelin activates the pituitary GHRHR exactly like endogenous GHRH does, which means it generates physiological GH pulses, preserves the somatostatin feedback loop, and doesn't override the negative feedback regulation the way exogenous recombinant hGH does. So you get IGF-1 elevation while keeping the GH-axis architecture intact, which is meaningfully different from pharmacological hGH replacement. For studying GH-axis pharmacology while preserving feedback regulation, this is the cleanest tool.

What we dont like is the half-life. Sermorelin has a serum half-life of roughly 10-15 minutes due to DPP-4 cleavage of the N-terminal residues, which means the GH pulse is short and the dosing has to be timed (typically evening to align with the physiological pulse). The short duration is exactly why Theratechnologies developed tesamorelin with the trans-3-hexenoyl modification to block DPP-4 cleavage, and why CJC-1295 was developed with a DAC modification for week-long activity. Sermorelin is the original, but it's been pharmacokinetically superseded.

Sourcing is reasonable for the 29-residue peptide. Standard Fmoc-SPPS handles it well, HPLC purity at 98%+ is widely achievable, and reputable vendors do clean work. Watch for the common issue of incomplete deprotection at the N-terminus, since DPP-4 is going to chew that end anyway.

For research where physiological GH pulsing is desired and the short half-life isn't a problem (or is actually useful for studying pulse pharmacology), sermorelin remains a sensible choice. The mechanism story is clean and the GH-axis preservation is the key feature that gets lost in conversations dominated by long-acting analogs.

Evidence: 75
Mechanism: 90
Reliability: 78
Safety: 80
Sourcing: 80
Value: 70
Signal: 65
Staying power: 65

Plain-language summary Intrigue 60 / 100

Sermorelin is the first 29 amino acids of growth hormone releasing hormone (the active portion). It triggers natural pulsatile growth hormone release from the pituitary. Approved historically for pediatric growth hormone deficiency before being discontinued in 2008. Not stocked by Kodiac. This monograph is provided for research and educational reference.

Intrigue 0–100 blends mechanism novelty, evidence strength, and translational potential. Kodiac editorial, not peer-reviewed.

GHRH 1-29 analog

A 29-amino-acid synthetic fragment of GHRH (residues 1-29) used for growth hormone deficiency diagnosis and treatment.

Abstract

Sermorelin (GRF 1-29; CAS 86168-78-7; molecular weight 3357.93) is a synthetic peptide consisting of the first 29 amino acids of human growth hormone releasing hormone (GHRH). The 1-29 fragment retains essentially all the GH-stimulating activity of full-length GHRH (44 residues) and was the basis for the FDA approval (under the trade name Geref) for GH deficiency in children. The brand-name product was discontinued in 2008 for commercial reasons; sermorelin is now compounded for clinical use in some jurisdictions and sold as a research chemical. The compound is administered subcutaneously and stimulates pituitary GH release through GHRH receptor activation, distinct from the ghrelin receptor agonism of GHRPs. Combination of sermorelin with a GHRP (ipamorelin, GHRP-2) produces synergistic GH release. Pharmacokinetics: plasma half-life 11 to 12 minutes; subcutaneous bioavailability good. Reported research dose ranges in the literature are around 0.3 mcg/kg subcutaneously.

Mechanism of action

GHRH receptor agonist (1-29 fragment retains GH-releasing activity). Synergistic with ghrelin receptor agonists.

Reported research dose ranges

Around 0.3 mcg/kg SC, or 200-500 mcg fixed dose (reported research dose ranges in the literature).

References

Walker RF. Sermorelin: a better approach to management of adult-onset growth hormone insufficiency? Clin Interv Aging 2006.

Read the full monograph

The full reference document covers compound identification, discovery and developmental history, mechanism of action, pharmacokinetics, reported research dose ranges, sourcing and quality verification, reconstitution and handling, stack interaction considerations, and a curated reference list. Available as a research-use-only PDF download.

KDC-MN-079

The full reference document is provided strictly for research use only. It reports research dose ranges from the published literature, not instructions for use in humans or animals.

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FOR RESEARCH USE ONLY. Not for medical, diagnostic, or therapeutic purposes. Not for human consumption. All information is provided for research and educational purposes only.

Kodiac sells research compounds for investigative use only.

Sermorelin

Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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Abstract

Mechanism of action

Reported research dose ranges

References

Read the full monograph

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