What It Is
Ipamorelin is a synthetic five-amino-acid growth hormone secretagogue and ghrelin-receptor agonist. FDA treats ipamorelin free base and ipamorelin acetate as distinct bulk substances and found that the nominations did not consistently identify which one was intended.[1] The National Cancer Institute describes its receptor-level pharmacology but does not identify an approved treatment use.[2]
Pharmacology
Early animal work described ipamorelin as relatively selective for growth-hormone release compared with older secretagogues at the tested exposures.[3] A small intravenous study in healthy men modeled drug exposure and the acute growth-hormone response.[4] Selectivity in an early experiment and a short-lived hormone response do not demonstrate improved body composition, sleep, recovery, longevity, or clinical safety.
What Human Studies Show
The largest cited clinical study tested intravenous ipamorelin for postoperative ileus in 117 bowel-resection patients. The difference in time to first tolerated meal was not statistically significant.[5] FDA concluded that effectiveness evidence for growth hormone deficiency or postoperative ileus was limited by any route and that no effectiveness data supported the proposed subcutaneous route.[1]
Online claims about fat loss, muscle gain, anti-aging, sleep, and recovery were not established in ipamorelin-specific controlled human outcome trials reviewed by FDA.
Safety and Unknowns
In the intravenous postoperative study, reported events included hypokalemia, insomnia, hyperglycemia, nausea, vomiting, abdominal distention, and two deaths; FDA stated that whether the deaths were related to ipamorelin was unclear.[1][5] That monitored hospital experience does not establish safety for subcutaneous use.
FDA found no safety data for the proposed subcutaneous route and identified unresolved concerns involving glucose intolerance, diabetes risk, unnatural amino acids, aggregation, peptide impurities, endotoxins, and immunogenicity.[1][6] There is no FDA-approved label or established human regimen.
Regulatory and Sport Status
Neither ipamorelin free base nor acetate is a component of an FDA-approved drug. In 2024 FDA proposed not adding either substance to the 503A Bulks List because of characterization gaps, lack of effectiveness evidence, and safety concerns.[1] Growth hormone secretagogues, including ipamorelin, are prohibited by WADA.[7]