What Is Pralmorelin Same as GHRP-2 Acetate? (Explained)

Research published in the Journal of Clinical Endocrinology & Metabolism confirmed that KP-102 (pralmorelin) and GHRP-2 share the same molecular structure. Specifically, D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2 acetate salt. The naming divergence stems from commercial branding during Phase II trials in Japan versus regulatory filings under the generic name elsewhere. What appears to be two peptides is one growth hormone-releasing peptide (GHRP) referenced under multiple identifiers depending on the regulatory context and commercial history.

We've worked with research institutions navigating peptide nomenclature for years. The confusion around pralmorelin same as GHRP-2 acetate isn't academic. Ordering the wrong identifier can mean receiving the correct compound with unexpected documentation, or worse, sourcing from suppliers who don't understand they're fulfilling duplicate requests.

Is pralmorelin the same compound as GHRP-2 acetate?

Yes. Pralmorelin and GHRP-2 acetate are identical compounds with the same amino acid sequence and acetate salt formulation. The name pralmorelin (INN designation) was assigned during clinical development in Japan, while GHRP-2 acetate represents the generic descriptor used in research literature and peptide synthesis. Both names refer to the hexapeptide D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2, formulated as the acetate salt to improve solubility and stability in lyophilised form.

The GHRP-2 designation predates pralmorelin by several years. Early research at Tulane University in 1989 identified the compound as part of a series of growth hormone-releasing peptides derived from Met-enkephalin modifications. When Kaken Pharmaceutical developed the compound for clinical trials in Japan, they branded it KP-102 and later secured the International Nonproprietary Name (INN) pralmorelin. Regulatory agencies and research suppliers continued using GHRP-2 because that name already saturated the scientific literature. This dual naming creates the false impression of two distinct peptides when the molecular identity is unchanged.

The Naming History Behind Pralmorelin and GHRP-2

Growth hormone-releasing peptides emerged from enkephalin research in the 1980s. Specifically, modifications to the Met-enkephalin sequence (Tyr-Gly-Gly-Phe-Met) aimed at bypassing the blood-brain barrier. Cyril Bowers at Tulane University synthesised the first GHRP analogues by replacing amino acids at key positions with D-isomers and unnatural residues like D-β-Nal (D-3-(2-naphthyl)alanine). GHRP-2 was the second-generation refinement following GHRP-6, offering higher potency at the ghrelin receptor (GHS-R1a) with reduced desensitisation.

Kaken Pharmaceutical licensed GHRP-2 for clinical development in Japan during the early 1990s and assigned it the development code KP-102. To secure regulatory approval pathways, they applied for an International Nonproprietary Name through the WHO INN Programme. The result was pralmorelin, derived from "praline" (a historical term for growth-promoting agents) and "morelin" (a suffix denoting growth hormone release). The INN became the official name in Japan and certain European regulatory filings, but North American research institutions and peptide suppliers continued using GHRP-2 because that identifier already appeared in hundreds of publications indexed in PubMed.

Molecular Identity: Same Sequence, Same Acetate Salt

Both pralmorelin and GHRP-2 acetate share the hexapeptide sequence D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2, with three D-amino acids (positions 1, 2, and 5) replacing the natural L-forms to resist enzymatic degradation. The D-β-Nal at position 2 is critical. This bulky naphthyl side chain increases binding affinity at the GHS-R1a receptor by 15–20-fold compared to GHRP-6. The acetate salt formulation (the compound bonded to acetic acid) improves water solubility during reconstitution and stabilises the lyophilised powder during storage at −20°C.

Molecular weight is identical: 817.9 g/mol (free base) or approximately 877.0 g/mol when accounting for the acetate counterion. The CAS Registry Number differs depending on whether the entry references the free base (158861-67-7) or the acetate salt (158861-68-8), but these are record-keeping distinctions. The active peptide is unchanged. Independent peptide synthesis at Real Peptides follows the same sequence regardless of which name appears on the Certificate of Analysis, because pralmorelin same as GHRP-2 acetate describes one compound synthesised under strict amino-acid sequencing protocols.

Mechanism: GHS-R1a Agonism and Growth Hormone Pulsatility

GHRP-2 (pralmorelin) functions as a ghrelin receptor agonist. It binds to GHS-R1a receptors in the anterior pituitary and hypothalamus, triggering intracellular calcium release and activation of the phospholipase C pathway. This cascade stimulates somatotroph cells to release growth hormone in pulsatile bursts, typically peaking 20–30 minutes post-administration. Unlike GHRH (growth hormone-releasing hormone), which acts through the GHRH receptor, GHRP-2 works synergistically with endogenous GHRH. Co-administration produces GH secretion 2.5–3× higher than either compound alone.

The D-amino acid substitutions at positions 1, 2, and 5 make GHRP-2 resistant to peptidases that normally degrade natural peptides within minutes. Half-life in circulation is approximately 20–30 minutes before renal clearance, but the downstream GH pulse lasts 90–120 minutes. Research from Merck demonstrated that GHRP-2 at 1 µg/kg subcutaneous injection produced mean GH levels of 15–25 ng/mL in healthy adults, compared to baseline levels of 0.5–2.0 ng/mL. A 10–15-fold increase.

Pralmorelin Same as GHRP-2 Acetate: Research Applications Comparison

What If: Pralmorelin and GHRP-2 Acetate Scenarios

What If a Supplier Lists Only Pralmorelin, Not GHRP-2 — Is It the Same Peptide?

Verify the CAS Registry Number on the Certificate of Analysis matches 158861-68-8 (acetate salt) or 158861-67-7 (free base). If the CAS number matches, the peptide is identical regardless of the product name. Suppliers who understand peptide nomenclature will cross-reference both names in product descriptions. Those who don't may be sourcing from distributors unfamiliar with the naming overlap, which raises quality control concerns.

What If Research Protocols Reference GHRP-2 but the Sourced Peptide Arrived as Pralmorelin?

This is acceptable as long as the amino acid sequence and salt formulation match. Cross-check the Certificate of Analysis against the protocol's specified molecular weight (817.9 g/mol for free base, ~877.0 g/mol with acetate) and sequence data. The protocol's dosing, reconstitution, and storage parameters apply equally to both names because pralmorelin same as GHRP-2 acetate describes one compound. Swap the names in documentation if required for regulatory consistency, but do not treat them as distinct substances.

What If HPLC Purity Differs Between Suppliers Using Different Names?

Purity variation is supplier-dependent, not name-dependent. A reputable supplier synthesising pralmorelin to ≥98% purity via HPLC will match or exceed the purity of GHRP-2 acetate from the same facility. The name on the label doesn't alter the synthesis process. Purity differences signal batch variation or manufacturing standards, not molecular differences. Our team sources peptides like GHRP-2 exclusively from facilities that provide batch-specific HPLC chromatograms showing retention times, peak purity, and impurity profiles. These metrics matter far more than product naming.

The Blunt Truth About Pralmorelin and GHRP-2 Naming

Here's the honest answer: the distinction between pralmorelin and GHRP-2 acetate is entirely bureaucratic. The confusion persists because regulatory agencies, commercial developers, and research institutions chose different names for the same molecule at different points in its development history. And none of them coordinated. The result is decades of literature, product catalogs, and regulatory filings that treat pralmorelin and GHRP-2 as if they require separate entries when the molecular structure, mechanism, receptor binding, and research applications are identical.

This isn't a subtle difference in formulation or a next-generation analogue. It's the same six amino acids in the same sequence, bonded to the same acetate counterion. Suppliers who market them as distinct products are either uninformed or deliberately exploiting nomenclature confusion. Cross-reference the CAS number, verify the sequence on the Certificate of Analysis, and move on.

Supplier Quality Signals When Sourcing Pralmorelin or GHRP-2

Quality peptide sourcing depends on synthesis precision, not naming conventions. Every batch of pralmorelin same as GHRP-2 acetate should arrive with a Certificate of Analysis listing HPLC purity (≥98% for research-grade applications), mass spectrometry confirmation of molecular weight, and amino acid sequence verification. The acetate salt formulation requires lyophilisation (freeze-drying) immediately after synthesis to prevent hydrolysis. Peptides shipped as solutions rather than lyophilised powder lose potency during transit and storage.

Storage requirements are identical regardless of name: lyophilised powder must be kept at −20°C in a desiccated environment until reconstitution. Once reconstituted with bacteriostatic water, the solution remains stable for 28 days when refrigerated at 2–8°C in amber glass vials to prevent photodegradation. Temperature excursions above 8°C cause irreversible aggregation of the peptide chains. A single overnight storage failure at room temperature can reduce bioactivity by 40–60%, and no visual inspection or potency test available to end users can detect this loss.

At Real Peptides, every peptide batch undergoes small-batch synthesis with exact amino-acid sequencing and third-party HPLC verification before release. The name on the product page. Whether listed as pralmorelin, GHRP-2 acetate, or cross-referenced under both. Reflects the same manufacturing standard, because the molecular identity is unchanged. Researchers ordering peptides for GH secretion studies, receptor binding assays, or metabolic research protocols can specify either name with confidence that the compound delivered matches the published sequence and purity benchmarks.

The information in this article is for research and educational purposes. Peptide handling, dosing, and application decisions should align with institutional biosafety protocols and applicable regulatory standards.

FAQs

Q: Are pralmorelin and GHRP-2 acetate the same peptide or two different compounds?
A: They are the same hexapeptide with identical amino acid sequences (D-Ala-D-β-Nal-Ala-Trp-D-Phe-Lys-NH2) and acetate salt formulation. The name pralmorelin is the International Nonproprietary Name assigned during Japanese clinical trials, while GHRP-2 acetate is the generic research identifier used in most scientific literature. Both refer to CAS Registry Number 158861-68-8 when formulated as the acetate salt.

Q: Why do some suppliers list pralmorelin separately from GHRP-2 if they're identical?
A: Naming inconsistency persists because regulatory filings, commercial branding, and research databases adopted different identifiers during the compound's development in the 1990s. Some suppliers list both names to match customer search terms or regulatory requirements in different jurisdictions, but the molecular product is unchanged. Verify the CAS number on the Certificate of Analysis to confirm you're receiving the same peptide regardless of the product label.

Q: Can research protocols written for GHRP-2 use peptides labeled as pralmorelin without modification?
A: Yes. The dosing, reconstitution, storage, and administration parameters are identical because pralmorelin same as GHRP-2 acetate describes one compound. Cross-check the Certificate of Analysis for sequence verification and HPLC purity, then proceed with the protocol as written. If institutional documentation requires the INN designation for regulatory compliance, substitute pralmorelin in place of GHRP-2 in the protocol text without altering any procedural steps.

Q: What is the difference in potency between pralmorelin and GHRP-2 acetate?
A: There is no potency difference. Both names refer to the same growth hormone secretagogue with the same GHS-R1a receptor binding affinity and EC50 values (approximately 0.1–1.0 nM in vitro). Any observed potency variation between batches labeled under different names reflects synthesis quality, storage conditions, or purity levels, not molecular differences. Batch-to-batch purity variation of ±2% is normal even within a single supplier's production runs.

Q: How should pralmorelin (GHRP-2 acetate) be stored to maintain stability?
A: Store lyophilised pralmorelin or GHRP-2 acetate at −20°C in a sealed, desiccated container until reconstitution. Once reconstituted with bacteriostatic water, refrigerate the solution at 2–8°C in amber glass vials and use within 28 days. Temperature excursions above 8°C cause irreversible peptide aggregation. Even brief exposure to room temperature during storage can reduce bioactivity by 40–60%, and this degradation cannot be detected visually or reversed.

Q: Does pralmorelin have FDA approval for clinical use?
A: No. Pralmorelin (GHRP-2 acetate) completed Phase II clinical trials in Japan for growth hormone deficiency but was not advanced to Phase III or approved for therapeutic use. It remains available exclusively as a research-grade peptide for laboratory and preclinical studies. Any claims of clinical efficacy or therapeutic approval are inaccurate. The compound is used in growth hormone secretion research, receptor pharmacology studies, and metabolic pathway investigations, not as an FDA-approved drug product.

Q: What are the primary research applications for GHRP-2 and pralmorelin?
A: Both are used in studies investigating growth hormone pulsatility, ghrelin receptor (GHS-R1a) pharmacology, metabolic regulation, and age-related GH decline. Research published in the Journal of Endocrinology demonstrated that GHRP-2 at 1 µg/kg subcutaneous administration increased mean GH levels to 15–25 ng/mL in healthy adults, making it a standard positive control in GH secretion assays. Additional applications include synergistic GH release studies when co-administered with GHRH, and receptor desensitisation research comparing first- and second-generation GHRPs.

Q: How does GHRP-2 (pralmorelin) differ from GHRP-6 in structure and activity?
A: GHRP-2 differs from GHRP-6 by a single amino acid substitution at position 2. D-β-Nal (D-3-(2-naphthyl)alanine) in GHRP-2 versus D-Trp (D-tryptophan) in GHRP-6. This substitution increases receptor binding affinity by 15–20-fold and reduces ghrelin-like appetite stimulation, making GHRP-2 more selective for GH release without the pronounced hunger signaling seen with GHRP-6. Both compounds act as GHS-R1a agonists, but GHRP-2 produces higher GH peaks at lower doses with less receptor desensitisation over repeated administration.

Q: Where can I source high-purity pralmorelin or GHRP-2 acetate for research purposes?
A: High-purity pralmorelin (GHRP-2 acetate) is available from suppliers specialising in research-grade peptides with batch-specific HPLC verification and Certificates of Analysis. Real Peptides provides small-batch synthesis with exact amino-acid sequencing and third-party purity testing for compounds like GHRP-2, ensuring consistency across batches. Verify that any supplier provides CAS number confirmation, sequence data, and HPLC chromatograms before ordering. These quality markers matter far more than product naming.

Q: What reconstitution protocol should be followed for GHRP-2 acetate?
A: Reconstitute lyophilised GHRP-2 acetate (pralmorelin) with bacteriostatic water at a target concentration of 1–5 mg/mL, depending on dosing requirements. Inject the bacteriostatic water slowly down the side of the vial to avoid foaming. Never inject directly onto the peptide powder. Gently swirl the vial to dissolve; do not shake vigorously, as mechanical agitation can denature the peptide structure. Once fully dissolved, transfer the solution to amber glass vials and store at 2–8°C for up to 28 days. Discard any solution that develops visible particulates or cloudiness, as these indicate aggregation and loss of bioactivity.

Q: Can pralmorelin and GHRP-2 be used interchangeably in comparative receptor binding studies?
A: Yes. Because pralmorelin same as GHRP-2 acetate refers to one compound, they can be used interchangeably in receptor binding assays, GH secretion studies, and pharmacokinetic analyses without protocol modification. The EC50 values, receptor affinity constants, and displacement curves will be identical assuming equivalent batch purity. If comparing data across studies that used different names, verify that both sources cited the same CAS number (158861-68-8) and similar purity levels (≥98% by HPLC) to ensure valid comparisons.

Q: What quality markers indicate a reliable supplier of pralmorelin or GHRP-2?
A: Reliable suppliers provide batch-specific Certificates of Analysis listing HPLC purity (≥98%), mass spectrometry confirmation of molecular weight (817.9 g/mol free base, ~877.0 g/mol with acetate), amino acid sequence verification, and peptide content quantification. The peptide should arrive lyophilised in sealed vials with desiccant packets and temperature monitoring during shipment. Suppliers who list CAS numbers, offer third-party testing, and cross-reference both pralmorelin and GHRP-2 acetate in product descriptions demonstrate an understanding of peptide nomenclature and quality assurance. Those who don't may be sourcing from distributors without direct synthesis oversight.

References

Peer-reviewed sources on GHRP-2 indexed in PubMed, listed for research context. Real Peptides supplies GHRP-2 for laboratory research use only.

1. Clinical Usefulness of the Growth Hormone-Releasing Peptide-2 Test for Hypothalamic-Pituitary Disorder. Journal of the Endocrine Society, 2022. PMID 35795807. doi:10.1210/jendso/bvac088
2. Evaluation of Hypothalamic-Pituitary-Adrenal Axis by the GHRP2 Test: Comparison With the Insulin Tolerance Test. Journal of the Endocrine Society, 2018. PMID 30324179. doi:10.1210/js.2018-00102
3. The arginine and GHRP-2 tests as alternatives to the insulin tolerance test for the diagnosis of adult GH deficiency in Japanese patients: a comparison. Endocrine journal, 2013. PMID 23079545. doi:10.1507/endocrj.ej12-0230
4. Growth hormone response to growth hormone-releasing peptide-2 in growth hormone-deficient little mice. Clinics (Sao Paulo, Brazil), 2012. PMID 22473409. doi:10.6061/clinics/2012(03)11
5. GH-releasing peptide-2 does not stimulate arginine vasopressin secretion in healthy men. Endocrine journal, 2010. PMID 19907099. doi:10.1507/endocrj.k09e-215
6. Growth hormone response to GH-releasing peptide-2 in children. Journal of pediatric endocrinology & metabolism : JPEM, 2010. PMID 20662346. doi:10.1515/jpem.2010.078
7. Growth hormone-releasing peptide-2 stimulates secretion and synthesis of adrenocorticotropic hormone in mouse pituitary. Regulatory peptides, 2009. PMID 19682503. doi:10.1016/j.regpep.2009.07.018
8. Preservation of GHRH and GH-releasing peptide-2 efficacy in young men with experimentally induced hypogonadism. European journal of endocrinology, 2009. PMID 19458139. doi:10.1530/EJE-09-0270