Discontinued Growth Hormone Axis

Ipamorelin

also known as: NNC 26-0161, Ipamorelin acetate

A selective ghrelin receptor agonist that stimulates GH release without the cortisol, prolactin, or ACTH spike seen with older GHRPs like GHRP-6.

A pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) identified in the 1990s at Novo Nordisk as a selective GH secretagogue with the cleanest hormonal specificity of the first-generation GHRP family.

Mechanism of action

Selective agonist at GHS-R1a (the ghrelin receptor) in the hypothalamus and pituitary, triggering pulsatile GH release through a pathway parallel to and synergistic with GHRH. Unlike GHRP-6 and GHRP-2, ipamorelin does not meaningfully elevate cortisol, ACTH, or prolactin at effective doses, which made it the preferred GHRP for clinical-style research protocols and is the primary reason it dominates community GH-axis stacks.

Primary uses

  • GH-axis research
  • Community protocols for body composition and recovery
  • Combination with CJC-1295 or mod GRF 1-29 in "GHRH + GHRP" stacks

Typical dosing

100–300 mcg 1–3 times daily (subcutaneous)

Community dosing only. Often injected pre-bed to align with endogenous GH pulse, and/or post-workout.

Regulatory status

Not approved. Novo Nordisk advanced it to Phase 2 for post-operative ileus but discontinued development. Widely sold in research-chemical and compounded channels.

References

  1. [pubmed] Raun K, et al. "Ipamorelin, the first selective growth hormone secretagogue." Eur J Endocrinol, 1998;139:552-561.
  2. [clinical-trial] Beck DE, et al. "Ipamorelin for the management of postoperative ileus in patients undergoing partial bowel resection: a multicenter, randomized, placebo-controlled phase 3 trial." J Gastrointest Surg, 2014.

Related peptides

CJC-1295

A long-acting GHRH analog engineered with a DAC linker that binds serum albumin, extending half-life from minutes to approximately 8 days.

Mod GRF 1-29

A short-acting GHRH analog — chemically identical to CJC-1295 but without the DAC albumin-binding linker — producing discrete GH pulses rather than sustained elevation.

GHRP-2

A second-generation GHRP approved as a diagnostic agent in Japan, with more pronounced GH-releasing potency than GHRP-6 but a meaningful prolactin and cortisol rise at higher doses.

GHRP-6

The prototype GHRP — a hexapeptide ghrelin receptor agonist notable for pronounced hunger stimulation and less favorable cortisol/prolactin profile than newer GHRPs.

Sermorelin

The N-terminal 29 amino acids of native GHRH — a former FDA-approved diagnostic and pediatric GH-deficiency therapy, now widely compounded for adult anti-aging protocols.
Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.