GHRP-2: Reference Overview and Reconstitution Notes

GHRP-2 (pralmorelin) is a man-made peptide (a short chain of building blocks called amino acids) that researchers study for its role in triggering growth hormone release. It is for research only and is not approved by the FDA in the United States.

GHRP-2

What it is

GHRP-2, also known as pralmorelin, is a man-made hexapeptide (a chain of exactly six amino acids) that belongs to the growth hormone releasing peptide (GHRP) family. Its amino acid sequence is D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2, its molecular weight is about 818 g/mol, and its CAS number (a unique ID number assigned to each chemical) is 158861-67-7.

Research context and categorization

GHRP-2 belongs to a group called growth hormone secretagogues. These are compounds that prompt the body to release its own growth hormone. GHRP-2 does this by acting on the ghrelin receptor (also called the growth hormone secretagogue receptor, or GHSR). Think of the receptor like a lock and GHRP-2 as a key. When it fits the lock, the pituitary gland (a small gland at the base of the brain) releases growth hormone.

Mechanisms and Appetite Effects

In research settings, GHRP-2 is studied mainly for the way it triggers bursts of growth hormone and for its effect on a downstream marker called IGF-1 (a protein the body produces in response to growth hormone). Researchers have also looked at it as a tool for testing whether the pituitary gland is releasing growth hormone properly.

GHRP-2 is also studied for its connection to appetite signaling, because the ghrelin receptor is tied to hunger signals. However, GHRP-2 tends to produce weaker appetite effects than a related compound called GHRP-6.

Regulatory and Approval Status

Japan has approved GHRP-2 (as pralmorelin) for one narrow use: as a diagnostic test for growth hormone deficiency. A "diagnostic" use means it helps check whether something is working normally, not treat a condition. Outside that narrow approval, other uses discussed in research or in fitness circles are not proven and not approved by the FDA. Any claims about performance, recovery, or body composition linked to GHRP-2 should be treated as unproven.

Key point: While Japan has approved GHRP-2 strictly as a diagnostic test agent for growth hormone deficiency, it remains an unapproved investigational compound in the United States and most other countries.

Status

• Regulatory status: Research-only in the United States and not FDA-approved. Japan allows it (as pralmorelin) for one specific diagnostic test, but it is not approved for general treatment anywhere.
• Sport status: Banned under the WADA Prohibited List (the global anti-doping rules for competitive sport). It falls under class S2 (Peptide Hormones, Growth Factors, Related Substances and Mimetics), specifically in the growth hormone secretagogue category, and is banned at all times, both in and out of competition.

Reconstitution notes (general)

GHRP-2 typically comes as a lyophilized (freeze-dried) powder. Think of it like a bouillon cube: the water has been removed so the material stays stable on the shelf. Before lab use, it is mixed back into liquid form using bacteriostatic water. This step is called reconstitution.

The working concentration follows a simple relationship: concentration equals the milligrams of peptide in the vial divided by the milliliters of water added. For example, adding 2 mL of water to a 5 mg vial gives a concentration of 2.5 mg/mL. To work out volumes for a specific target concentration, use the calculator at peptide calculator.

Dilution and handling notes (compound-specific)

Solubility and Reconstitution Volume

GHRP-2 is a short, simple hexapeptide. It dissolves easily and fully in bacteriostatic water. It does not form a gel, turn cloudy, or drop out of solution the way some larger or more complex peptides can.

A common approach is to reconstitute a 5 mg or 10 mg vial with about 1 to 3 mL of bacteriostatic water. The choice is mostly about convenience rather than any solubility limit. A smaller volume makes the solution more concentrated, while using 2 mL or 3 mL makes it easier to read small volumes on a graduated syringe (a syringe with measurement markings along the side).

Mixing Best Practices

Bacteriostatic water (which contains about 0.9 percent benzyl alcohol as a preservative) is preferred over plain sterile water. The preservative slows breakdown of the peptide after the vial is opened. When mixing, follow these key steps:

• Aim the stream of water at the inside glass wall of the vial, not directly at the powder.
• Swirl gently rather than shaking. Shaking creates foam, and vigorous agitation can damage the fragile peptide chains.
• Make sure the final solution looks clear and colorless.

If the liquid stays cloudy or shows visible particles after gentle swirling, something is wrong with the material or the mixing process. That is not normal behavior for this compound.

Handling and storage

Store the freeze-dried powder, and the reconstituted solution, in a refrigerator at 2 to 8 C and away from direct light. Wipe the rubber stopper on the vial with an alcohol swab before drawing from it, and write the reconstitution date on the label.

Once mixed, GHRP-2 is far less stable than the dry powder. A refrigerated working window of about 4 weeks is a common reference point, with longer-term storage handled by freezing. Discard the vial if the contents become cloudy or discolored, or if floating particles appear.

Related reading

• GHRP-6
• Hexarelin
• Humanin
• How Reconstitution Works
• How Long Does a Reconstituted Vial Last?

Tools and supplies

• peptide calculator
• Bacteriostatic Water 30 ml
• Gansulin Metal Reusable Pen
• 3 ml Glass Cartridges (10-pack)
• Complete Starter Kit

Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.

Frequently asked questions

What is GHRP-2 and how does it work in research?

GHRP-2 is a synthetic hexapeptide (MW ~818 g/mol, CAS 158861-67-7) that binds the ghrelin receptor (GHSR), prompting pituitary growth hormone release; it is studied as a growth hormone secretagogue for laboratory research only.

Is GHRP-2 FDA-approved or legal for research use?

GHRP-2 is not FDA-approved. Japan permits it narrowly as a diagnostic agent (pralmorelin) for GH deficiency testing. It remains investigational in the US and is banned by WADA under class S2 at all times.

How is lyophilized GHRP-2 reconstituted for laboratory use?

Add bacteriostatic water to the lyophilized vial; working concentration (mg/mL) equals mg of peptide divided by mL of water added. Example: 5 mg + 2 mL = 2.5 mg/mL. Follow aseptic technique per laboratory protocol.

More in our bacteriostatic water and diluents collection.

What the research community gets wrong about GHRP-2

• GHRP-2 is not the same as GHRP-6. They are often swapped in notes and labels, but they have different amino acid sequences and behave differently at the bench. In the published literature GHRP-2 is described as producing weaker appetite signaling than GHRP-6, so treating the two as interchangeable can confuse how a study is recorded.
• The name does not mean it contains growth hormone. GHRP-2 (pralmorelin) is a six amino acid peptide that acts on the ghrelin receptor (GHSR). It is a signaling molecule studied in that role, not a form of growth hormone itself, so calling a vial of GHRP-2 a growth hormone vial is simply wrong.
• Japan approval does not mean broad approval. Pralmorelin is cleared in Japan only as a diagnostic test agent for growth hormone deficiency. That is a narrow research and testing use, not a general treatment approval, and it is not FDA approved in the United States. Reading the Japan clearance as a green light for other uses misstates the record.
• A bigger reconstitution volume does not add material. The milligrams in the vial stay the same no matter how much bacteriostatic water you add. More water just makes the concentration (mg per mL) lower and easier to read on a graduated syringe. Picture the volume as changing the strength of the label number, not the amount of peptide present.
• The dry powder and the mixed solution are not equally stable. Lyophilized GHRP-2 is stable on the shelf, but once it is in liquid it is far more fragile. Leaving a reconstituted vial at room temperature, or shaking it hard enough to foam, is a common handling mistake that can damage the peptide.

From our bench: If you reconstitute GHRP-2 at your bench, tell us what you actually observed. About how long did the lyophilized powder take to fully dissolve when you aimed the bacteriostatic water down the glass wall and swirled gently, and did the finished solution read as clear and colorless? We are collecting real, dated observations (vial size, water volume used, and time to a clear solution) so other researchers can compare notes. Share your numbers and we will add them here with credit.

Sources

1. Bacteriostatic Water for Injection, USP , FDA/DailyMed label (0.9% benzyl alcohol)
2. Duerkop et al., Biotechnol J 2018 , Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation
3. Sigma-Aldrich (Merck) , Handling and Storage Guidelines for Peptides and Proteins
4. PubChem: Pralmorelin (GHRP-2), CID 6918245 , chemical identity and structure
5. Okano et al., Rapid Commun Mass Spectrom 2010 , LC/ESI-MS/MS determination of pralmorelin (GHRP-2) and its metabolite in human urine (PubMed 20552695)
6. Nishi et al., Int J Mol Sci 2016 , GHRP-2 and PKC-induced inflammation in human ovarian granulosa cells (PMC5000754)