Growth Hormone Peptides

MK-677 (Ibutamoren) is an orally-active growth hormone secretagogue that mimics the action of ghrelin. Unlike peptide injections, it is taken orally and has a long half-life allowing once-daily dosing. Clinical trials have demonstrated increases in GH and IGF-1 levels, improved bone density, and enhanced lean body mass. Despite reaching Phase 2 trials, it was never approved by the FDA.

CJC-1295 is a synthetic analog of growth hormone releasing hormone (GHRH) that stimulates the pituitary gland to release growth hormone. It exists in two forms: with DAC (Drug Affinity Complex) for extended half-life, or without DAC for shorter duration. The peptide is popular in anti-aging and bodybuilding communities for its ability to increase GH levels, potentially improving body composition, recovery, and sleep quality.

Ipamorelin is a pentapeptide that selectively stimulates growth hormone release by mimicking ghrelin, the hunger hormone. Unlike many other GH secretagogues, ipamorelin does not significantly increase cortisol or prolactin levels, making it a "cleaner" option with fewer side effects. It is commonly stacked with CJC-1295 for synergistic effects on GH production.

GHRP-6 is a synthetic hexapeptide and one of the first growth hormone releasing peptides developed. It stimulates GH secretion by activating the ghrelin receptor. Unlike later-generation peptides like ipamorelin, GHRP-6 significantly increases appetite and also stimulates cortisol and prolactin release. It has been studied for treating GH deficiency, cachexia, and age-related muscle loss.

Sermorelin is a bioidentical synthetic version of growth hormone releasing hormone (GHRH) consisting of the first 29 amino acids of the full 44-amino acid GHRH molecule. It is FDA-approved for diagnostic testing of GH secretion but is widely used off-label for anti-aging and growth hormone optimization. Unlike direct HGH replacement, sermorelin stimulates the body's own production of growth hormone.

Tesamorelin is an FDA-approved synthetic growth hormone releasing hormone analog specifically indicated for reducing excess abdominal fat in HIV-infected patients with lipodystrophy. Clinical trials demonstrated significant reductions in visceral adipose tissue without affecting subcutaneous fat. While approved only for HIV-related lipodystrophy, it has gained interest for targeting stubborn abdominal fat.

Hexarelin is a synthetic hexapeptide GH secretagogue that is significantly more potent than GHRP-6. Beyond stimulating growth hormone release, research has revealed unique cardioprotective effects independent of GH. However, chronic use leads to desensitization, reducing its effectiveness over time.