What is Sermorelin + Ipamorelin? Components, Mechanism and Research Overview

Sermorelin + Ipamorelin is a 1:1 co-lyophilized blend pairing the unmodified native GHRH fragment with a selective ghrelin-receptor pentapeptide. Its distinguishing feature is what the GHRH side does not have: sermorelin is human GHRH (1-29) amide with no substitutions, no acyl cap and no albumin-binding linker. It is the reference molecule the modified analogues were built from, and its short reported persistence — roughly ten to twenty minutes in published pharmacokinetic work — is a property rather than a defect. Where a study is about pulse structure and somatotroph responsiveness rather than sustained exposure, the native fragment is the more faithful tool.

MyPeptide supplies Sermorelin + Ipamorelin as a 1:1 co-lyophilized powder in 10 mg (5 mg/5 mg) and 20 mg (10 mg/10 mg) vials within the growth hormone blends range. Research use only; not for human or veterinary use.

What is in the vial

Origin and structure of the two components

Sermorelin is GRF (1-29) amide: the first 29 residues of the 44-residue human growth hormone releasing hormone, terminating in an amide. Truncation studies in the early 1980s established that this fragment retains the full receptor-activating capacity of the intact hormone, which made it the natural starting point for every subsequent GHRH analogue. Because the sequence is unmodified, the Tyr1-Ala2 bond remains a substrate for dipeptidyl peptidase-4, and clearance is correspondingly rapid.

Sermorelin also has an unusual regulatory history for a research peptide: it was previously an approved prescription product in the United States, used in paediatric growth hormone deficiency and as a diagnostic agent for pituitary function, and was withdrawn from the market in 2008 for commercial rather than safety reasons. Detail is in our sermorelin explainer, and the contrast with the substituted 29-residue analogue is worked through in CJC-1295 vs sermorelin.

Ipamorelin is a synthetic pentapeptide from Novo Nordisk's 1990s programme, built around aminoisobutyric acid and D-2-naphthylalanine. Published preclinical and human pharmacology reported growth hormone release without the concurrent cortisol, ACTH and prolactin elevations seen with GHRP-2, GHRP-6 and hexarelin — the selectivity that keeps it in current blends. Our ipamorelin explainer covers the structure.

How the combination is thought to work

Both peptides act on the same pituitary somatotroph through different receptors and different second messengers. The GHRH receptor is Gs-coupled: agonism raises cAMP and activates protein kinase A. The ghrelin receptor is Gq-coupled: agonism drives phospholipase C, inositol trisphosphate generation and a rise in intracellular calcium. Studies combining a GHRH-class compound with a GHRP-class secretagogue have consistently reported a larger secretory response than either alone, and secretagogue action at GHS-R1a has additionally been described as blunting somatostatin tone, permitting a fuller GHRH-driven response.

The blend's practical character comes from sermorelin's short persistence. Both components clear quickly, so the exposure profile is a sharp pulse rather than a sustained elevation — closer to the endogenous secretory pattern than a long-acting analogue produces, and correspondingly better suited to questions about pulse amplitude, receptor responsiveness and desensitisation kinetics. Where sustained exposure is what a study needs, an albumin-binding or acyl-capped GHRH analogue is the better-matched tool.

One arithmetic point: a 1:1 mass ratio is not a 1:1 molar ratio. At 3,357.93 against 711.85 g/mol, five milligrams of sermorelin is about 1.49 µmol while five milligrams of ipamorelin is about 7.02 µmol — roughly 4.7 moles of ipamorelin per mole of sermorelin. A co-lyophilized vial also fixes that proportion; varying it requires separate Sermorelin and Ipamorelin vials, a trade-off covered in peptide blends versus single vials.

What the research has examined

Pituitary function and diagnostic pharmacology

Sermorelin's largest human literature is diagnostic: it was used to probe pituitary somatotroph responsiveness and to distinguish hypothalamic from pituitary causes of growth hormone deficiency. Those studies characterise the GHRH receptor response in people in considerable detail.

Paediatric growth hormone deficiency

Clinical work supporting the former approved product examined growth velocity in children with GHRH-responsive deficiency. This describes the prescription medicine, administered under medical supervision, not research-grade material.

Combined GHRH and secretagogue pharmacology

A separate literature from the 1990s onward administered GHRH or sermorelin together with a GHRP-class secretagogue and reported synergy at the pituitary. Much of this work used sermorelin specifically, which makes it more directly relevant to this blend than to blends using engineered analogues.

Sleep and ageing models

Because growth hormone secretion is tied to slow-wave sleep, several studies have examined GHRH-class compounds in sleep-architecture models, including in older adults with reduced secretory amplitude. Findings are exploratory.

What has not been established

No controlled studies exist of this co-formulated product, and no data establish that a 1:1 mass ratio is optimal for any research question. Blend composition is a formulation convention rather than an evidence-based specification.

Forms and sizes we supply

Both sizes are co-lyophilized into a single vial, so one reconstitution produces a solution containing both peptides at the stated ratio. The 10 mg (5 mg/5 mg) vial suits shorter series; the 20 mg (10 mg/10 mg) vial is the more economical unit where a longer study should run on one lot. Each lot carries a certificate reporting purity per component at ≥99% by HPLC.

Reconstitution and storage in a lab context

The blend reconstitutes as a single material. Bacteriostatic water is used where the vial will be drawn from repeatedly; sterile water where a preservative would interfere with the assay. Solvent is directed down the vial wall and the vial swirled rather than shaken.

Because the ratio is 1:1, the arithmetic is symmetrical. A 10 mg (5/5) vial made up with 2 mL of diluent gives 5 mg/mL total, which is 2.5 mg/mL of each peptide; 0.1 mL — the 10-unit mark on a U-100 syringe — contains 250 mcg of sermorelin and 250 mcg of ipamorelin. The 20 mg (10/10) vial made up with 4 mL gives the same per-volume figures. Method detail is in our reconstitution guide.

One handling note specific to sermorelin: the sequence contains a methionine at position 27, an oxidation-prone residue that the CJC-1295 family removes by substituting leucine. Native sermorelin keeps it, so protection from light, air and warm storage matters more here than for the engineered analogues. Lyophilized vials are held at −20 °C; reconstituted solution at 2–8 °C for the study window, with aliquoting and freezing for longer work. General practice is in how to store peptides.

Purity, COA and how to read a blend certificate

Three things distinguish a good two-component certificate. Purity should be reported for each peptide separately, not as a single combined number. Mass spectrometry should confirm both expected masses, 3,357.93 g/mol and 711.85 g/mol; for sermorelin specifically, an observed mass 16 Da above the expected value indicates methionine oxidation and is worth querying. And the HPLC trace should resolve two peaks whose relative areas are consistent with the labelled 1:1 mass ratio.

Regulatory status

Sermorelin was formerly an approved prescription product in the United States and was withdrawn from the market in 2008; there is no current approved product, and research-grade material has never been that product and carries none of its approvals. Ipamorelin has no marketing authorisation anywhere. Material supplied here is a research-use-only chemical for laboratory investigation by qualified personnel — not a supplement, not a medicine, and not for human or veterinary administration. GHRH analogues and growth hormone secretagogues are prohibited in sport under anti-doping rules.

Related blends and further reading

Keeping ipamorelin and changing the GHRH-side partner gives CJC-1295 (No DAC) + Ipamorelin, which substitutes four residues to resist degradation, and Tesamorelin + Ipamorelin, which uses the full 44-residue sequence with an N-terminal acyl cap.