Research library / Compounds

What is ?

A five-residue peptide described in 1998 as the first selective growth hormone secretagogue.

is a synthetic pentapeptide that causes the pituitary to release growth hormone. Novo Nordisk scientists described it in 1998 as the first selective growth hormone secretagogue, because in their animal studies it released growth hormone without raising stress hormones. Prism Labs supplies it as a 10 mg lyophilized vial.

Prism Labs editorial · Updated September 10, 2026 · 3 min read

Lyophilized vial10mg · 99.71% purity$49.99View product

What it is

Its sequence is Aib–His–D-2-Nal–D-Phe–Lys–NH2. Three of the five residues are non-standard: Aib (α-aminoisobutyric acid), D-2-naphthylalanine and D-phenylalanine. The reference record lists the formula C38H49N9O5 and a molecular weight of 711.9 g/mol (PubChem CID 9831659).

Sources: [1] PubChem · reference structure · [2] European Journal of Endocrinology · 1998

Where it came from

It came from a Novo Nordisk chemistry program built on the growth hormone-releasing peptides (GHRPs), small synthetic peptides known to release growth hormone. It was identified in a series of compounds lacking the Ala–Trp pair at the center of GHRP-1.

In 1999, researchers identified the body’s own ligand for the receptor these peptides act on: ghrelin, a 28-amino-acid peptide from the stomach.

Sources: [2] European Journal of Endocrinology · 1998 · [3] Nature · 1999

Lyophilized vial from Prism Labs — Every lot ships with its own certificate of analysis.

What “selective” means

Earlier GHRPs released growth hormone but also raised ACTH and cortisol. In the 1998 swine studies, GHRP-6 and GHRP-2 did both, while did not raise ACTH or cortisol beyond the levels seen with GHRH itself, even at many times the amount needed to release growth hormone.

None of the secretagogues tested changed FSH, LH, prolactin or TSH. That profile, similar to GHRH’s, is why the paper called it the first selective growth hormone secretagogue.

Sources: [2] European Journal of Endocrinology · 1998

What researchers have studied

Most of its literature is preclinical:

Growth hormone release in rat pituitary cells, anesthetized rats and swine, in the 1998 paper.
Longitudinal bone growth in rats, in 1999.
The ghrelin receptor (GHS-R) it acts through.

These are observations in laboratory models. They are not evidence about any use in people. It is also one half of .

Sources: [2] European Journal of Endocrinology · 1998 · [4] Growth Hormone & IGF Research · 1999 · [3] Nature · 1999

How it is supplied and stored

ships as a lyophilized (freeze-dried) powder in 10 mg vials. The powder is stable at room temperature in transit. For lab use it is reconstituted with bacteriostatic water such as .

Concentration is content divided by volume: 10 mg in 2 mL gives 5 mg per mL. The reconstitution calculator handles other combinations.

For storage before and after reconstitution, see how to store lyophilized peptides.

How to verify a batch

Every lot has its own certificate of analysis from an independent lab. Read three results separately:

Identity: confirms the expected compound was detected.
Purity: the share of the measured material that is the intended compound.
Content: the amount measured, compared with the label.

Then match the lot number on your vial or bottle to the report, and use the report’s verification link to confirm it with the testing lab. Step by step: how to read a peptide COA.