Sermorelin + GHRP-6

What Is the Sermorelin + GHRP-6 Blend?

The sermorelin + GHRP-6 blend is a supplier-defined formulation that combines sermorelin, a GHRH analogue, with GHRP-6, a synthetic growth hormone-releasing hexapeptide. It is listed as a 10 mg vial by total peptide content, and the listings tracked here do not state a standard split between the two components.

Sermorelin corresponds to GRF(1-29), the first 29 residues of human growth hormone-releasing hormone^[1]. GHRP-6 has the sequence His-D-Trp-Ala-Trp-D-Phe-Lys-NH2^[2] and was the first hexapeptide of its class to be studied extensively in humans^[3].

The premixed blend is not an approved or standardized product. Unlike most GHRH-plus-secretagogue blends, however, the underlying pairing of GHRH with GHRP-6 has been tested in human endocrine studies.

Components at a Glance

The blend pairs a 29-residue GHRH analogue with a six-residue secretagogue that acts on a separate receptor.

Molecular weights are PubChem values (CID 16132413 for sermorelin and CID 4345065 for GHRP-6).

Why These Compounds Are Studied Together

GHRH and GHRP-6 release GH through different mechanisms, and human studies that gave them together recorded larger GH responses than either produced alone. Those studies used GHRH in acute endocrine testing, not sermorelin in a premixed blend.

Separate mechanisms

GHRPs have no structural homology with GHRH and act through specific receptors; proposed mechanisms include counteracting somatostatin and acting partly through GHRH^[3]. A 1998 review describes a dual and complementary action of GHRPs on the hypothalamus and pituitary^[6], and a 1993 review of animal and human work reported that GHRP-6 releases GH independently of GHRH and somatostatin^[2]. GRF(1-29)-NH2, meanwhile, activates adenylate cyclase through the GRF receptor^[4].

Combined administration in humans

• Hypothyroidism (randomized study): in healthy controls, mean peak GH was 24.9 µg/L after GHRH, 22.1 µg/L after GHRP-6 and 77.4 µg/L after both together. In patients with primary hypothyroidism, the blunted GHRH response (4.1 µg/L) rose to 52.8 µg/L with the combination^[5].
• Type 2 diabetes: in 12 men, hyperglycemia lowered the peak GH response to combined GHRH + GHRP-6 compared with a euglycemic clamp^[7].
• Diagnostic testing: GH responses to GHRP-6 alone or to GHRH plus GHRP-6 were almost completely blocked in patients with pituitary stalk transection, and the combined test was proposed for adult-onset GH deficiency^[8].

These studies support the receptor-level rationale for pairing the two classes. They do not test sermorelin specifically, a fixed-ratio blend, or repeated exposure.

Because each supplier sets the blend ratio, researchers typically verify both peptides and their stated amounts with HPLC and mass spectrometry certificates of analysis.

Research Status

The sermorelin + GHRP-6 blend has no regulatory approval and is supplied for laboratory research use only. Sermorelin acetate was previously FDA approved as a single agent but was discontinued in the United States in 2008. GHRP-6 has not been approved.

GHRH and its analogues are prohibited in sport by WADA, and laboratories have developed mass spectrometry methods to detect sermorelin^[9]. A 2026 review notes that most published peptide studies examine controlled therapeutic regimens rather than combined protocols, and that products in unregulated supply chains are often mislabeled or contaminated^[10].

Evidence quality is mixed: small human endocrine studies of GHRH given with GHRP-6, animal studies of GHRP-6 alone in injury models^[11], and no study of the premixed formulation. A review covering sermorelin, GHRP-6 and other secretagogues notes that a paucity of clinical data limits understanding of these compounds^[12].