GHRP-6

What it is

GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide, a chain of six amino acids, and one of the original growth hormone-releasing peptides. It was first described in 1984 and was the first hexapeptide of its kind to be studied extensively in humans. It stimulates growth hormone (GH) release and produces a pronounced increase in appetite through ghrelin-receptor activation.

In the PeptidesAI encyclopedia it is categorized under growth hormone.

How it's thought to work

GHRP-6 is an agonist of the ghrelin receptor, also called the growth hormone secretagogue (GHS) receptor. It stimulates GH release and strongly signals hunger. In healthy men, submaximal doses of GHRP-6 combined with growth hormone-releasing hormone (GHRH) stimulated GH release synergistically, which is the sense in which it is described as synergistic with GHRH analogs.

What the research says

The 1984 report of the hexapeptide described a dose-related GH release in the laboratory and in animals, without release of LH, FSH, TSH or prolactin. In a 1990 study of 18 men, GHRP-6 given by intravenous injection raised GH in a dose-related way and acted synergistically with GHRH. No adverse clinical effects or laboratory abnormalities were reported with it, and serum prolactin and cortisol rose about two-fold only at the highest dose tested. A later review describes the GH-releasing effect of GHRPs as reproducible but partly desensitizing.

GHRP-6 is not FDA-approved.

Reported side effects

The PeptidesAI encyclopedia lists a pronounced increase in appetite, water retention, tingling, and mild cortisol and prolactin elevation at higher doses. The cortisol and prolactin rise at the highest dose is consistent with what the 18-man study reported.

Reconstitution

GHRP-6 is supplied as a lyophilized (freeze-dried) powder and is typically reconstituted with bacteriostatic (BAC) water before use. It commonly comes in 5 mg and 10 mg vials. The amount of peptide in the vial is fixed; the water added only changes how concentrated the solution is.

Worked example. A 5 mg vial is 5,000 mcg. Reconstituted with 2 mL of BAC water, that works out to 5,000 mcg ÷ 2 mL = 2,500 mcg/mL. On a U-100 insulin syringe, where each unit is 0.01 mL, each unit holds 2,500 × 0.01 = 25 mcg. Use the peptide reconstitution calculator to work out the concentration and units for any vial size and water volume.

Important notes

GHRP-6 is not FDA-approved. The encyclopedia lists strong appetite stimulation among its features.

Sources

1. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone. Bowers CY et al. Endocrinology, 1984. Preclinical
2. Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone. Bowers CY et al. J Clin Endocrinol Metab, 1990. Human trial
3. Growth hormone-releasing peptides. Ghigo E et al. Eur J Endocrinol, 1997. Review

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Frequently asked questions

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