Ipamorelin

Overview

Torsena supplies research-grade Ipamorelin to qualified laboratories across the European Union. Furthermore, we hold stock in Europe, so orders ship without intra-EU customs delay. Batch documentation is available on request.

Lot & Supply Format

• Purity. Typically ≥99%, and a batch-specific CoA is available on request.
• Formulation. Mannitol-free, so no bulking agents or buffer salts dilute the material.
• Presentation. Lyophilized peptide, sealed in glass research vials.
• Quantities. Single vials as standard, though we also quote bulk on request.
• Shipping. Dispatched from Europe, and always with temperature-appropriate packaging.

What is Ipamorelin?

Ipamorelin is a synthetic pentapeptide and a selective agonist at the growth hormone secretagogue receptor, GHS-R1a, which is also the ghrelin receptor. Novo Nordisk developed it under the code NNC 26-0161, and Raun and colleagues published the characterising work in 1998 under the title “Ipamorelin, the first selective growth hormone secretagogue”.

That word “selective” is the whole point of the compound. Earlier secretagogues such as GHRP-6 and hexarelin activate GHS-R1a but also stimulate ACTH, cortisol and prolactin pathways, so any observed effect carries confounding endocrine activity alongside it. Ipamorelin was optimised specifically to strip that out. Consequently it became the standard tool where a protocol needs GHS-R1a engagement without the rest.

Researchers frequently pair it with a GHRH receptor agonist such as Modified GRF (1-29), because the two receptors feed pituitary somatotroph function through separate second messenger systems.

Supplied exclusively for in-vitro and ex-vivo research by qualified laboratories. Not intended for human or animal administration.

Why a Five-Residue Peptide Survives

Short peptides are usually fragile, so Ipamorelin’s stability deserves explanation. Three of its five residues are non-standard.

Position	Residue	Type
1	Aib	α-aminoisobutyric acid, non-proteinogenic
2	His	Standard L-amino acid
3	D-2-Nal	D-2-naphthylalanine, non-proteinogenic
4	D-Phe	D-enantiomer
5	Lys-NH2	Standard L-amino acid, C-terminally amidated

Proteases recognise L-amino acid backbones. Therefore a sequence built largely from D-enantiomers and non-proteinogenic residues presents very little that they can cleave, and the C-terminal amidation removes the free carboxyl that carboxypeptidases would otherwise attack. This is engineered resistance rather than incidental stability.

Mechanistic Overview

GHS-R1a activation. Ipamorelin binds the growth hormone secretagogue receptor type 1a, a G-protein coupled receptor expressed on pituitary somatotrophs and in hypothalamic nuclei. Activation stimulates GH release through intracellular calcium mobilisation and protein kinase C signaling. Notably this is a different second messenger route from the GHRH receptor, which uses cAMP and PKA.

Selectivity. Binding studies characterise cross-reactivity at other pituitary hormone pathways as negligible. Specifically, and in contrast to GHRP-6 and hexarelin, Ipamorelin does not meaningfully stimulate ACTH or cortisol release in experimental models, nor does it activate prolactin secretion at research-relevant concentrations. Therefore effects observed with Ipamorelin can be attributed to GHS-R1a engagement with more confidence than with the earlier compounds.

Complementarity with GHRH agonists. Because GHS-R1a and the GHRH receptor use separate second messenger systems, concurrent application produces a combined response that published work describes as exceeding the sum of either alone. Consequently pairing Ipamorelin with Modified GRF (1-29) is among the most common designs in somatotroph signaling research.

The GHS Pharmacophore

Ipamorelin belongs to a structural family, and the relationship is visible in the sequences.

Compound	Sequence	Shared C-terminus
Ipamorelin	Aib-His-D-2-Nal-D-Phe-Lys-NH2	D-Phe-Lys-NH2
GHRP-2	D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2	D-Phe-Lys-NH2
GHRP-6	His-D-Trp-Ala-Trp-D-Phe-Lys-NH2	D-Phe-Lys-NH2

All three terminate identically, and that shared D-Phe-Lys-NH2 motif is the conserved GHS-R1a binding element. Therefore the differences that produce Ipamorelin’s selectivity sit at the N-terminal end rather than at the receptor-binding end, which is why structure-activity work on this family concentrated there.

Ipamorelin vs GHRP-6

Characteristic	Ipamorelin	GHRP-6
Length	5 amino acids	6 amino acids
Molecular weight	711.85 Da	872.44 Da
Receptor	GHS-R1a, selective	GHS-R1a, non-selective
ACTH and cortisol	Minimal in studies	Elevated in studies
Prolactin	Minimal in studies	Elevated in studies
Research focus	Selective GH axis signaling	Broad GHS receptor pharmacology
CAS number	170851-70-4	87616-84-0

Research Applications

• Somatotroph signaling. Cultured anterior pituitary assays, and likewise GH secretion endpoints.
• Receptor selectivity profiling. Comparative work against non-selective secretagogues, namely GHRP-6 and hexarelin.
• Dual agonist protocols. Combination with GHRH analogs, particularly where pathway convergence is the question.
• Calcium and PKC signaling. Second messenger studies, since GHS-R1a uses a distinct route from the GHRH receptor.
• Ghrelin receptor pharmacology. GHS-R1a is the ghrelin receptor, so the compound appears in appetite and energy balance research too.

Published Research Data

Key reference:
Raun K, Hansen BS, Johansen NL, et al. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998;139(5):552-561.

Ipamorelin research peptide specifications

Chemical name	Ipamorelin
Synonyms	NNC 26-0161
CAS number	170851-70-4
Molecular formula	C38H49N9O5
Molecular weight	711.85 g/mol
Sequence	Aib-His-D-2-Nal-D-Phe-Lys-NH2
Peptide length	5 amino acids
Non-standard residues	Aib, D-2-Nal, D-Phe
C-terminus	Amidated
Type	Linear, modified
Typical purity	≥99% (HPLC / MS)
Physical form	White lyophilized powder
Additives	None, mannitol-free
Storage	-20°C, sealed, protected from light
Intended use	In-vitro / ex-vivo laboratory research only

Because the sequence carries no cysteine and no methionine, the formula contains no sulfur, and the theoretical mass is unambiguous. Therefore mass spectrometry confirms identity cleanly against a CoA.

Reconstitution & Storage

• Solvent. Sterile water or a suitable aqueous buffer.
• Stability. The non-standard residues confer good resistance to standard handling, though this is not a reason to be careless.
• Short-term storage. 2-8°C for reconstituted aliquots.
• Long-term storage. Aliquot, then freeze at -20°C.
• Freeze-thaw. Minimise cycles regardless.

Keep lyophilized material at -20°C and protect it from light. Furthermore, let vials warm to room temperature before opening, because condensation otherwise pulls moisture into the powder. Note that no methionine or cysteine is present, so inert-atmosphere handling is unnecessary here. Otherwise follow your institutional SOPs.

Analytical Documentation

We provide batch-specific Certificates of Analysis on request. Typically the documentation covers three areas.

• Purity. Determined by reverse-phase HPLC.
• Identity. Confirmed by mass spectrometry.
• Physical checks. Namely appearance and solubility verification.

Why Choose Torsena for Ipamorelin

• Documentation. We send batch CoAs on request, and they cover both HPLC purity and MS identity.
• No fillers. Mannitol-free, so nothing dilutes the material you paid for.
• EU distribution. We ship from European stock, and therefore intra-EU orders clear no customs.
• Direct contact. You reach the team directly, rather than a ticket queue.

Frequently Asked Questions

What is the molecular weight of Ipamorelin?
Ipamorelin weighs 711.85 g/mol with the formula C38H49N9O5. The sequence is Aib-His-D-2-Nal-D-Phe-Lys-NH2, and since it contains no cysteine or methionine the formula carries no sulfur, so mass spectrometry verifies identity cleanly.

What makes Ipamorelin selective?
It activates GHS-R1a with negligible cross-reactivity at other pituitary hormone pathways. Unlike GHRP-6 and hexarelin, it does not meaningfully stimulate ACTH or cortisol release, nor prolactin secretion at research-relevant concentrations. Raun and colleagues characterised this in 1998, and their paper title, “Ipamorelin, the first selective growth hormone secretagogue”, states the claim directly.

Why is such a short peptide stable?
Because three of its five residues are non-standard. Aib is non-proteinogenic, and both 2-Nal and Phe are D-enantiomers, so proteases that recognise L-amino acid backbones have little to cleave. The C-terminal amidation also removes the free carboxyl that carboxypeptidases would target. This is engineered resistance rather than incidental stability.

How does Ipamorelin relate to GHRP-2 and GHRP-6?
All three share the same C-terminal D-Phe-Lys-NH2 motif, which is the conserved GHS-R1a binding element across the family. Their differences sit at the N-terminal end, and that is where the structure-activity work producing Ipamorelin’s selectivity was concentrated.

Why pair Ipamorelin with a GHRH agonist?
Because the two receptors use different second messenger systems. GHS-R1a signals through calcium and PKC, while the GHRH receptor signals through cAMP and PKA. Published work describes the combined response as exceeding the sum of either alone, since the pathways converge on somatotroph output without competing.

Related Research Compounds

Researchers working on growth hormone axis signaling usually look at these as well.

• Tesamorelin. A GHRH analog, and therefore the complementary receptor arm, since GHRH-R and GHS-R1a converge on somatotroph function by separate routes.
• CJC-1295 + Ipamorelin. The co-lyophilised preparation, namely where a protocol uses both agonists together.

Otherwise, browse the full catalog at the Torsena shop.