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Ipamorelin
It's marketed as the "gentle" growth hormone secretagogue because it doesn't raise cortisol the way older compounds do — a real, documented property. Its one real clinical-outcome trial found no benefit over placebo, and FDA's advisory committee has voted against it for compounding eligibility.
In brief
Should you care? Yes — its one real clinical trial is a negative result, which is a meaningfully different and more specific finding than "never been tested."The short version
- Selective GH release without a cortisol spike — a real, documented pharmacological property, mostly established in animal work.
- Its one human clinical-outcome trial found no benefit over placebo for postoperative bowel recovery.
- FDA's advisory committee voted against it for compounding eligibility in late 2024.
What it is
Ipamorelin is a pentapeptide, a selective agonist of the ghrelin receptor (GHS-R1a), characterized as the first growth hormone secretagogue that doesn't cross-react with ACTH/cortisol release — a selectivity property first established in pig studies, not human ones.
What the evidence shows
A Phase 1 dose-escalation study in 40 healthy male volunteers confirmed dose-proportional GH release with a roughly 2-hour half-life (Gobburu et al., Pharm Res 1999;16:1412-1416, PMID 10496658) — a real human pharmacokinetic finding. The one clinical-outcome trial that exists is a multicenter, double-blind, placebo-controlled Phase 2 study testing IV ipamorelin for postoperative ileus after bowel resection (Beck et al., Int J Colorectal Dis 2014;29(12):1527-1534): it found no significant difference from placebo on either the primary or secondary efficacy endpoints, despite good tolerability.
Regulatory status
Ipamorelin has never been approved anywhere. FDA's Pharmacy Compounding Advisory Committee reviewed ipamorelin acetate at its 29 October 2024 meeting and voted against its inclusion on the 503A bulks list, closing the path to Category 1 compounding eligibility.
What isn't supported
No trial of any kind supports ipamorelin for muscle gain, fat loss, sleep or longevity — the uses it's actually sold for. The one real clinical-outcome trial that was run, for a completely different purpose, found it didn't work.
References
- Gobburu et al., "Pharmacokinetic-Pharmacodynamic Modeling of Ipamorelin, a Growth Hormone Releasing Peptide, in Human Volunteers," Pharm Res 1999;16(9):1412-1416, PMID 10496658.
- Beck et al., "Randomized clinical trial of IV ipamorelin for postoperative ileus after colorectal resection," Int J Colorectal Dis 2014;29(12):1527-1534.
- FDA, Pharmacy Compounding Advisory Committee meeting, 29 October 2024; committee voted against ipamorelin's inclusion on the 503A bulks list.