MK-677

Ipamorelin is a synthetic pentapeptide growth hormone secretagogue developed by Novo Nordisk and derived from GHRP-1. It is researched mainly for stimulating the body's own growth hormone (GH) release, and was studied in humans primarily for postoperative ileus and gut motility rather than anti-aging. It is not an approved drug anywhere: it reached Phase II trials, was discontinued for insufficient efficacy, and is now sold only as a research chemical.

CJC-1295 is a synthetic analog of growth hormone-releasing hormone (GHRH), specifically a modified GHRH(1-29), engineered for a long duration of action. The form most people mean by CJC-1295 includes a Drug Affinity Complex (DAC) that binds blood albumin to extend its half-life to roughly 6 to 8 days, raising GH and IGF-I for days from a single injection. It was developed by ConjuChem, reached Phase II trials and was abandoned; it is not an approved drug and is sold only as a research chemical. A version without DAC (Modified GRF 1-29) acts for only about 30 minutes.

GHRP-6 is a synthetic six-amino-acid peptide (His-D-Trp-Ala-Trp-D-Phe-Lys-NH2) that tricks the body into releasing its own growth hormone. It was one of the first growth hormone secretagogues ever made, and the hunt to find out why it worked led scientists straight to the discovery of ghrelin. It has no approval as a drug anywhere and is used only as a research compound.

GHRP-2 (generic name pralmorelin) is a synthetic hexapeptide growth hormone secretagogue and a second-generation cousin of GHRP-6. It prompts the pituitary to release growth hormone and is the one peptide in this family with an actual regulatory approval: it is licensed in Japan as a diagnostic agent for growth hormone deficiency. Outside that narrow diagnostic use it has no approval and is sold elsewhere only as a research compound.

Tesamorelin is a stabilized analog of growth-hormone-releasing hormone (GHRH 1-44) with a chemical modification that protects it from rapid breakdown. It is FDA-approved (brand name Egrifta) to reduce excess visceral abdominal fat in people with HIV-associated lipodystrophy, which makes it one of the few growth-hormone-axis peptides with a real approval behind it. Its evidence base is solid for that specific population and thinner for the general anti-aging and fat-loss uses it gets promoted for online.

Sermorelin is a 29-amino-acid fragment of human growth hormone-releasing hormone (GHRH), and it is the shortest piece of GHRH that still works fully. It asks the pituitary to make and release its own growth hormone rather than injecting GH itself. It was once an FDA-approved drug for diagnosing and treating growth hormone deficiency in children, but the manufacturer pulled it from the market in 2008, so today it is available mainly through compounding pharmacies for off-label use.