Ipamorelin

Overview

Ipamorelin was developed in the late 1990s by Novo Nordisk as one of the cleanest GHRP compounds. Its primary advantage over older GHRPs (GHRP-2, GHRP-6) is high selectivity — it does not significantly raise cortisol or prolactin at research doses.

Selectivity Profile — Its Defining Feature

The foundational study (Raun et al., 1998) tested ipamorelin against the older GHRPs and found a striking difference: while GHRP-6 and GHRP-2 both raised ACTH and cortisol, ipamorelin did not raise ACTH or cortisol above the levels seen with GHRH alone — even at doses more than 200× the ED50 for GH release. None of the secretagogues affected FSH, LH, prolactin, or TSH in that model.

| Hormone | GHRP-6 | GHRP-2 | Ipamorelin | |---------|--------|--------|------------| | GH | ↑↑↑ | ↑↑↑ | ↑↑↑ | | ACTH / Cortisol | ↑↑ | ↑↑ | ↔ (not significant) | | Appetite | ↑↑↑ | ↑↑ | ↑ (milder) |

This clean ACTH/cortisol profile is why ipamorelin is often preferred over older GHRPs. (Note: this selectivity was characterized in animal models; it is the basis of the compound's reputation, not a claim from a large human trial.)

The CJC-1295 + Ipamorelin Stack

Combining ipamorelin with a GHRH analog like CJC-1295 (Mod-GRF 1-29) is one of the most popular community protocols. The mechanistic rationale is complementary:

• CJC-1295 (GHRH analog): raises the amplitude of the GH pulse
• Ipamorelin (GHRP / ghrelin-receptor agonist): initiates a GH pulse and suppresses somatostatin

In theory the two produce a larger, synergistic GH release than either alone. Important caveat: this synergy is a mechanistic and community-driven expectation — there is no controlled human trial of the specific ipamorelin + CJC-1295 combination. Typical community dosing is 100 mcg CJC-1295 + 100–200 mcg ipamorelin, subcutaneously, ~30 minutes before sleep.

Honest Evidence Framing

The human evidence base for ipamorelin is thin. It rests on essentially two solid human datasets — the Gobburu 1999 PK study (40 volunteers, ~2-hour half-life, single GH-release episode) and the Beck 2014 Phase 2 trial for postoperative ileus, which failed its primary endpoint — plus the preclinical Raun 1998 pharmacology. There are no successful pivotal efficacy trials and no long-term human safety data.

Regulatory Status

Ipamorelin is not FDA-approved for any human indication. Notably, at an October 2024 FDA advisory committee meeting, the committee voted against adding ipamorelin to the 503A compounding bulks list, and FDA had placed it in Category 2 (significant safety concerns). It is sold only as a research chemical and is prohibited in sport.