Ipamorelin
Summary
Ipamorelin is a selective growth hormone secretagogue (a ghrelin-receptor agonist) characterized in 1998 preclinical work for releasing GH with minimal cortisol or prolactin elevation. Human data are thin: early pharmacology studies plus one phase 2 trial for postoperative ileus that did not meet its primary endpoint.
Mechanism
Ipamorelin is a five-amino-acid peptide that acts as an agonist at the ghrelin receptor (GHS-R1a) in the pituitary and hypothalamus. Receptor activation triggers a pulse of growth hormone release from somatotrophs. Its distinguishing feature in preclinical work is selectivity: it provokes strong GH release with minimal elevation of cortisol, prolactin, or ACTH, unlike older growth hormone-releasing peptides such as GHRP-6.
Reported effects
Ratings are relative to peers in the same category, not absolute claims.
Studied dosing — research context
Published human work used intravenous administration in early pharmacology studies and a phase 2 trial in bowel-resection patients. No published trial has studied subcutaneous dosing regimens for body-composition or performance outcomes in humans. This describes research protocols, not guidance.
Research context only. This is not a recommendation.
Safety
Human safety data are limited to early pharmacology studies and one phase 2 trial, in which the compound was generally tolerated with no major safety signal reported. There are no long-term safety studies, and no published data on repeated or chronic use in healthy adults. The selectivity profile was established with pharmaceutical-grade material; products of unknown provenance may differ.
Limitations
The only completed human RCT tested ipamorelin for postoperative bowel recovery, not body composition, performance, or aging — and it missed its primary endpoint. There are no published trials testing the outcomes the compound is commonly discussed for. Preclinical selectivity findings may not translate to gray-market products of unknown identity and purity.