GHRP-2 Nasal Spray

Description

This GHRP-2 nasal spray supplies GHRP-2, also known as growth hormone releasing peptide-2 or pralmorelin, a synthetic hexapeptide with the sequence H-D-Ala-D-2Nal-Ala-Trp-D-Phe-Lys-NH2, molecular formula: c45h55n9o6, molecular weight approximately 817.97 Da, CAS 158861-67-7. It came out of Cyril Bowers’ structure-activity programme on GH-releasing peptides acting via the anterior pituitary gland and hypothalamus, and it holds a distinction none of its relatives, such as hexarelin, sermorelin or tesamorelin, can claim. Supplied for laboratory research use only.

The only growth hormone secretagogue any regulator has approved

Dozens of compounds in this class have been synthesized and studied since the 1980s. Exactly one has been approved by a national regulatory authority, and it is this one.

In October 2004 Japan’s Pharmaceuticals and Medical Devices Agency approved pralmorelin as a diagnostic agent for assessing growth hormone deficiency and short stature in adults and children, marketed by Kaken Pharmaceutical. The detail worth holding onto is what it was approved for. Not treatment. Not body composition, bone density, fat metabolism, metabolic processes and lipolysis, tissue repair, muscle gain, or muscle growth. Not ageing. A diagnostic test, where the peptide is given to provoke a GH response—often compared to the action of endogenous GHRH, L-DOPA, arginine, and the inhibition of somatostatin—so that the response itself can be measured and the pituitary assessed.

That is a meaningful regulatory precedent, and it is also a narrow one. It establishes that the compound reliably and reproducibly provokes GH release in humans, which is exactly what a provocative GH secretagogue diagnostic requires. It establishes nothing about therapeutic benefit, such as increased protein synthesis, muscle repair, changes in insulin-like growth factor 1, energy levels, or appetite regulation and appetite stimulation, from repeated use, because that was never the question the approval answered. Pages that cite the Japanese approval as evidence of efficacy are stretching it well past what it says.

What the position 1 and 2 substitutions do

Compared with the prototype hexapeptide of this family, GHRP-6, GHRP-2 carries two changes at the front of the molecule. Position 1 holds D-alanine in place of histidine, and position 2 holds D-2-naphthylalanine in place of D-tryptophan. Positions 3 through 6 are shared across the family: alanine, tryptophan, D-phenylalanine, and a C-terminal lysine amide.

Both substitutions pull in the same direction. The naphthylalanine at position 2 is a larger, more rigid aromatic system than tryptophan, and it is reported to give stronger binding affinity at the ghrelin receptor, also known as the GHS-R or growth hormone secretagogue receptor. The D-alanine at position 1 replaces a residue that aminopeptidases can attack with one they handle poorly, improving stability. Together these produce a compound with greater potency than the unmodified prototype, which is the practical reason it, rather than the original, became the compound that reached a regulator.

For assay design this is a reminder that potency and stability are entangled in peptide pharmacology. A compound that survives longer in your medium will look more potent in a long incubation than one that does not, even if their receptor affinities are similar. If you are comparing members of this family, matching exposure time and accounting for differential degradation is what makes the comparison mean anything.

Endocrine cross-reactivity is the experimental confound

This is the part that changes how you design an experiment with GHRP-2, and it is the reverse of the property that defines ipamorelin.

GHRP-2 is reported to raise cortisol and prolactin alongside growth hormone, particularly at higher concentrations. In a whole-animal or whole-pituitary preparation, that means a GH signal arrives accompanied by a stress-axis signal, and any downstream readout or signaling cascade you measure, such as changes in pain perception, could be responding to either.

The practical consequence: if your endpoint is anything that cortisol also influences, such as insulin sensitivity or the regulation of TNF-alpha, and cortisol influences a great deal, you cannot attribute the result to GH signalling on the basis of GHRP-2 exposure alone. Two controls resolve it. Measure ACTH, cortisol and prolactin alongside GH so you know what your system actually released and how it affects energy balance. And run a selective GHS-R1a agonist in parallel: if the selective ghrelin receptor agonist reproduces your effect, GH signalling is a sufficient explanation, and if it does not, something else in the hormonal response is contributing. This is the single most useful thing to build into intranasal GHRP-2 research, where mucosal bioavailability is a factor common to peptide sprays, or any cell-based work with this compound.

The constitutive activity baseline

One property applies to every compound acting at this receptor and it is easy to overlook. GHS-R1a has the highest known constitutive activity of any G protein-coupled receptor, signalling at roughly 50 percent of maximum with no agonist present, as reviewed in work on GHS-R1a constitutive activity. Your unstimulated baseline is not zero, and the window available for an agonist to show an effect is compressed accordingly. An inverse agonist control gives you a real floor to measure against; vehicle alone does not. Cryo-EM structures of the active receptor, including PDB 7W2Z, are reported in Nature Communications.

GHRP-2 nasal spray specifications

Core identity data for this GHRP-2 nasal spray. Quote the sequence and CAS number in your methods section rather than the product name.

GHRP-2 nasal spray storage and handling

GHRP-2 sits in the middle of this family for stability. The D-alanine at position 1 and the C-terminal amide close both exopeptidase routes, and three of the six residues are D-configured, so it resists enzymatic breakdown better than an unmodified sequence.

Light is the specific vulnerability. The molecule carries a tryptophan at position 4 and a naphthylalanine at position 2, both large aromatic systems, and aromatic residues are the ones that suffer from light exposure and oxidation, leading to potential oxidative stress on the peptide’s integrity. Amber containers or foil covering, short bench time, and discarding discoloured solution are justified precautions rather than excessive ones.

Sound GHRP-2 nasal spray storage is otherwise routine: cold, sealed, single-use aliquots (often reconstituted from a lyophilized peptide or GHRP-2 peptide vial in bacteriostatic water for stability or found in a GHRP-2 pre-mixed pen) rather than repeated freeze-thaw on one container, and low-binding plasticware at the low concentrations used in receptor work.

How research grade GHRP-2 spray is characterized

The verification issue specific to this molecule is stereochemistry, and it is more pointed here than for most. Three of the six residues are D-configured, at positions 1, 2 and 5. D and L amino acids are isobaric, so mass spectrometry confirms the composition but cannot confirm the configuration, and a peptide with an L residue where a D belongs would pass a mass check while behaving differently at the receptor. Chiral analysis or a validated synthetic route is the relevant assurance, and it is a fair question to put to any supplier.

Alongside that, a research grade GHRP-2 spray is characterized by reversed-phase HPLC for purity and mass spectrometry for identity near 817.97 Da. This material is supplied under the same verification PrymaLab applies across its research peptides, HPLC and MS confirmation plus independent third-party testing. No specific lot figures are asserted here; request the certificate of analysis for the lot you receive.

For the receptor pharmacology of this compound class or other research agents like nootropics such as Semax, BPC-157, MOTS-c, and GHK-Cu, see the growth hormone-releasing peptides overview in the PrymaLab Research Library.

Frequently asked questions

What is GHRP-2?

GHRP-2, also called pralmorelin, is a synthetic peptide and hexapeptide, D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2, about 817.97 Da, CAS 158861-67-7, acting at GHS-R1a. Material supplied here is a research chemical for in-vitro laboratory use only.

Is GHRP-2 an approved drug?

It was approved in Japan in October 2004 as a diagnostic agent for assessing growth hormone deficiency, marketed by Kaken Pharmaceutical. That is a diagnostic clearance, not a treatment approval, and it carries no FDA approval. It is the only growth hormone secretagogue any national regulator has approved.

What do the position 1 and 2 substitutions do?

D-alanine at position 1 resists aminopeptidase attack, improving stability. D-2-naphthylalanine at position 2 is a larger, more rigid aromatic system reported to increase binding affinity at the ghrelin receptor. Together they give greater potency than the unmodified prototype hexapeptide.

Why does cortisol matter when designing a GHRP-2 experiment?

Because GHRP-2 is reported to raise cortisol and prolactin alongside growth hormone, particularly at higher concentrations. Any downstream endpoint that cortisol also affects cannot be attributed to GH signalling without measuring those hormones or running a selective GHS-R1a agonist in parallel.

Is GHRP-2 nasal spray approved for human use?

No. This material is a research chemical for in-vitro laboratory use only and is not intended for human or veterinary use. Its diagnostic approval in Japan has no bearing on research-chemical material sold elsewhere. Nothing here is medical advice.

Ordering and compliance

Every PrymaLab research compound ships from the United States and is sold research-use-only. This GHRP-2 peptide nasal spray is supplied for in-vitro laboratory research, is not intended for human or veterinary use, is not a drug, supplement or sports product, and has not been evaluated by the FDA for the research-chemical context. Verify the legal status of any research compound in your jurisdiction before ordering. Certificates of analysis are available on request for the lot you receive.