Growth hormone-releasing peptide 6

GHRP-6 in Canada

Also known as Growth hormone-releasing peptide 6 · Growth hormone-releasing hexapeptide · His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 · SKF-110679

GHRP-6 is a synthetic six-amino-acid peptide and the first growth hormone-releasing peptide shown to work in a living animal. It acts on the ghrelin receptor to trigger a pulse of growth hormone from the pituitary, and it is the GHRP with the most pronounced hunger effect — a property that follows directly from the receptor it shares with ghrelin. Canada Peptides carries research-grade GHRP-6 as a lyophilised vial, priced and shipped in CAD for laboratory and research use only.

Quick facts

Class: Synthetic hexapeptide; ghrelin receptor (GHS-R1a) agonist
Structure: 6 amino acids · His-D-Trp-Ala-Trp-D-Phe-Lys-NH2 · ~873 Da · two D-amino acids
Half-life: Short — reported on the order of 15–60 minutes after intravenous dosing; the GH pulse it triggers lasts roughly 1–2 hours
Route in research: Intravenous, subcutaneous, intranasal and oral in human studies; subcutaneous and intraperitoneal in animal work
Cadence in research: Single doses in most human studies; once to three times daily in animal and mechanistic protocols
Storage: Lyophilised: refrigerated, dark. Reconstituted: refrigerated, used within weeks
Status in Canada: No Health Canada market authorisation or DIN. Research use only

Pharmacology

GHRP-6 is an agonist at GHS-R1a, a G-protein-coupled receptor expressed in the anterior pituitary and the hypothalamus. Activation in the pituitary drives calcium influx in somatotroph cells and releases stored growth hormone; activation in the hypothalamus is thought to increase GHRH release and suppress somatostatin, which is why the effect is amplified by, and partly dependent on, an intact hypothalamus. The result is a discrete GH pulse rather than a sustained elevation, and the pituitary's normal feedback — via IGF-1 and somatostatin — remains in place.

The same receptor explains the side profile. GHS-R1a in the arcuate nucleus signals through NPY and AgRP neurons, the circuit ghrelin uses to drive hunger, and GHRP-6 activates it. Studies in humans reported increased hunger and food intake after GHRP-6 that ghrelin research later reproduced almost exactly. Cortisol and prolactin release follow from receptor activity in the hypothalamic–pituitary–adrenal axis and in lactotroph cells respectively; GHRP-6 produces smaller rises than GHRP-2 or hexarelin and larger ones than ipamorelin.

A second, less-known thread is cytoprotection. Ghrelin receptors and the related CD36 scavenger receptor are expressed in cardiac and other tissues, and a Cuban group has published rodent and pig studies reporting that GHRP-6 reduced infarct size and protected against ischaemia–reperfusion injury and organ fibrosis. This work is smaller, largely from one institute, and has not been tested in humans.

Pharmacokinetically the peptide is short-lived. The two D-amino acids protect it from rapid peptidase cleavage compared with a native hexapeptide, but plasma half-life after intravenous dosing is still reported in the range of tens of minutes, and the GH pulse it triggers peaks around 15–30 minutes and returns to baseline within roughly two hours. Oral and intranasal bioavailability was measured in early human work and found to be low but sufficient to raise GH — one reason the compound was once considered as an oral GH secretagogue before non-peptide molecules took that role.

GHRP-6 FAQ

Is GHRP-6 for sale in Canada?

Yes. Research-grade GHRP-6 is available in Canada from Canada Peptides as a lyophilised vial, priced and shipped in CAD. It is supplied strictly for laboratory and research use, not for human consumption.

What is GHRP-6?

GHRP-6 is a synthetic six-amino-acid peptide developed in Cyril Bowers's laboratory and reported in 1984 as the first synthetic peptide to release growth hormone in a living animal. It acts on the ghrelin receptor, GHS-R1a, and triggers a pulse of growth hormone from the pituitary.

What does the research on GHRP-6 actually show?

A large human physiology literature confirms that GHRP-6 reliably raises growth hormone, synergises with GHRH, and also increases hunger, cortisol and prolactin. What it does not contain is any adequately powered trial of a clinical outcome over time.

What is the half-life of GHRP-6?

Short. Plasma half-life after intravenous dosing is reported on the order of tens of minutes, and the growth hormone pulse it triggers peaks within 15–30 minutes and returns to baseline in roughly two hours. Human pharmacokinetic data for repeated subcutaneous dosing is sparse.

How was GHRP-6 dosed in studies?

Human physiology studies most often used a single 1 µg/kg intravenous bolus, sometimes combined with 1 µg/kg GHRH. There is no validated human dose for any therapeutic purpose, and this page does not recommend one; the material sold here is for research use only.

Why does GHRP-6 cause hunger?

Because it activates the same receptor ghrelin uses to signal hunger in the hypothalamus. The appetite effect was documented in human studies before ghrelin was discovered and is the main reason GHRP-6 is distinguished from ipamorelin, which was designed to avoid it.

What side effects does GHRP-6 research report?

Single-dose human studies report increased hunger, flushing, transient drowsiness and modest rises in cortisol, ACTH and prolactin, with no serious adverse events. There is no long-term human safety data, which is why the FDA declined to permit it in compounded medicines in 2023.

Is GHRP-6 legal in Canada?

GHRP-6 is not a controlled substance in Canada, but it has no Health Canada approval for human use and no DIN. It may be sold for laboratory research, which is how it is sold here. It is prohibited for tested athletes under WADA's S2 category.

GHRP-6 in Canada

Quick facts

GHRP-6 — for sale in Canada

What is GHRP-6?

Evidence at a glance

Pharmacology

Identity and chemistry

Storage and stability

Research indications

Research protocols

Interactions and stacking in research

Reconstitution and handling

Side effects and safety signals

Regulatory status in Canada

Further reading

GHRP-6 FAQ

Research references