GH secretagogues are not one peptide with several brand names. They fall into two receptor families.
GHRH analogs (sermorelin, tesamorelin, CJC-1295) act at the growth hormone-releasing hormone receptor. Ghrelin mimetics (GHRP-6, GHRP-2, hexarelin, ipamorelin) act at the ghrelin receptor (GHSR). Mixing the names, or treating "CJC + ipamorelin" as two strengths of one drug, is a category error.
This page is the class map. Pairwise chemistry, PK, and ACTH/cortisol detail live on the comparison pages linked below. It is not a protocol.
Research notice: Research-grade peptides discussed here are for laboratory research only. They are not approved for human consumption, medical treatment, or diagnosis. FDA-approved medicines (Egrifta) are separate from research-grade material.
| Family | Ligands in this guide | Receptor | Human evidence cited here |
|---|---|---|---|
| GHRH analogs | Sermorelin, tesamorelin, CJC-1295 | GHRH receptor | Geref-era sermorelin review; tesamorelin phase 3 HIV lipodystrophy; CJC-1295 healthy-adult GH/IGF-I and pulsatility |
| Ghrelin mimetics | GHRP-6, GHRP-2, hexarelin, ipamorelin | GHSR | GH release in men; hexarelin ACTH/cortisol/PRL; GHRP-2 food-intake RCTs; ipamorelin IV PK/PD |
There is no verified head-to-head RCT of "the GHRH analog class versus the GHRP class" in the sources below.
Guillemin, Brazeau, Bohlen et al. isolated a 44-residue amidated GH-releasing peptide from a human pancreatic tumor that caused acromegaly. Rivier, Spiess, Thorner, and Vale characterized a GH-releasing factor from a human pancreatic islet tumor the same year. Those papers are the GHRH sequence foundation.
Native GRH(1-44)-NH2 is short-lived. Frohman et al. reported an HPLC half-life of 6.8 minutes after IV injection, with cleavage to a weakly active GRH(3-44)-NH2 fragment. Later analogs add N-terminal protection (tesamorelin) or albumin tethering (CJC-1295) for that reason.
Howard et al. cloned a pituitary and hypothalamus receptor that functions in GH release. That is the receptor the GHRP class uses. Kojima et al. identified ghrelin as the endogenous acylated GH-releasing peptide from stomach.
The two receptors are the split this guide is built on. See Ipamorelin vs CJC-1295 for that pair in isolation.
Full analog-by-analog tables are on GHRH analogs compared. The DAC naming problem is on CJC-1295 with DAC vs without DAC.
Sermorelin is GHRH(1-29). Prakash and Goa described it as the shortest synthetic peptide with full biological activity of GHRH, used as an IV provocative test of GH secretion and, in limited data, as once-daily subcutaneous treatment in some prepubertal children with idiopathic GH deficiency. Height-velocity increases with sermorelin were less than with somatropin in the comparisons that review summarized. Transient facial flushing and injection-site pain were the most commonly reported adverse events. That is a 1999 review of Geref-era literature, not a research-vial schedule. There is no current FDA-approved sermorelin product in the sources cited on the GHRH analog page.
Tesamorelin is a GHRH(1-44) analog with a trans-3-hexenoyl group on the N terminus. Falutz et al. (NEJM 2007) randomized 412 HIV-infected patients with abdominal fat accumulation. Visceral adipose tissue decreased 15.2% with tesamorelin and increased 5.0% with placebo over 26 weeks. IGF-I increased 81.0% versus a 5.0% decrease. Glycemic measures did not differ significantly between groups in that report. The pooled phase 3 analysis (Falutz 2010, n=806) found a week-26 VAT treatment effect of -15.4%. Tesamorelin is an FDA-approved product (Egrifta) for that HIV-lipodystrophy indication. Research-grade tesamorelin listings are not Egrifta.
CJC-1295 in the literature is not unmodified sermorelin. Jette et al. identified it as tetrasubstituted hGRF(1-29) plus a C-terminal albumin-binding maleimide. Teichman et al. reported that after a single injection in healthy adults, mean GH rose 2- to 10-fold for 6 days or more, mean IGF-I rose 1.5- to 3-fold for 9-11 days, and estimated half-life was 5.8-8.1 days. Ionescu and Frohman found overnight pulses persisted one week later: trough GH 7.5-fold, mean GH 46%, IGF-I 45%. Marketplace names such as "CJC-1295 no DAC" are not that albumin-binding analog. CJC-1295 is not an FDA-approved therapeutic in the sources cited.
This site has a CJC-1295 peptide page. It does not currently have separate peptide pages for sermorelin or tesamorelin.
Class ACTH/cortisol/PRL detail is on Ghrelin mimetics compared. The GHRP-2 versus GHRP-6 cell and cAMP split is on GHRP-2 vs GHRP-6.
GHRP-6 is the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2. Bowers et al. gave it by IV bolus to 18 normal men, alone and with GHRH-(1-44)-NH2. Mean peak serum GH after placebo and three GHRP dose levels was 1.2, 7.6, 16.5, and 68.7 micrograms/L. Submaximal GHRP plus GHRH stimulated GH synergistically. At the highest GHRP dose, serum PRL and cortisol rose about 2-fold. Those IV amounts are trial methods, not a use protocol.
GHRP-2 is a later hexapeptide in the same chemical class. Cheng et al. concluded that, in rat primary pituitary cells, GHRP-2 and GHRP-6 share receptor and mechanism: no additive GH at maximal concentrations, cross-desensitization, GHRP antagonist block. Wu et al. showed species splits on cAMP: GHRP-2 increased cAMP in sheep somatotrophs; GHRP-6 did not, in that system. Laferrere, Abraham, Russell et al. (2005) reported that GHRP-2, like ghrelin, increased food intake in healthy men. Laferrere, Hart, and Bowers (2006) reported that obese subjects also increased food intake after GHRP-2. A comparable GHRP-6 human food-intake RCT is not among the sources cited here.
Hexarelin substitutes 2-methyl-Trp into the GHRP-6 backbone. Deghenghi et al. reported GH-releasing activity in infant and adult rats. Ghigo et al. (1994) gave hexarelin IV, subcutaneous, intranasal, and oral to healthy young volunteers. Arvat et al. found GHRP-2 and hexarelin produced similar GH responses and similar PRL, ACTH, and cortisol increases in young adults. This site does not currently have a hexarelin peptide page.
Ipamorelin was characterized by Raun et al. as the first selective GH secretagogue in its series. In rat pituitary cells it released GH with potency similar to GHRP-6, via a GHRP-like receptor, not by mimicking GHRH. In swine, GHRP-6 and GHRP-2 raised ACTH and cortisol; ipamorelin did not above GHRH-like levels. Gobburu et al. infused ipamorelin over 15 minutes in healthy men: terminal half-life 2 hours, GH peaking at 0.67 hours. Infusion rates are study methods, not a protocol.
Bowers 1990 is the human GHRP plus GHRH synergy paper. Cheng 1997 is the rat-cell result that two GHRPs at saturating concentrations do not add further GH. Those are reasons not to treat two GHRPs as independent GH channels, and not a reason this page would publish a combined protocol.
Different receptors (GHSR versus GHRH) are a mechanistic fact. They are not a use instruction.
Related comparisons: GHRH analogs, ghrelin mimetics, GHRP-2 vs GHRP-6, ipamorelin vs CJC-1295, CJC-1295 DAC vs no DAC. Category hub: growth hormone peptides.
Peptide calculator
Peptide reconstitution protocol
GH secretagogues & growth peptides (category guide)
Your brand here — Reach our audience of peptide researchers and boost your sales.