Ipamorelin

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"Ipamorelin" redirects here. For other uses, see Ipamorelin (disambiguation).
Medical disclaimer. This article is for informational purposes only and does not constitute medical advice. Consult a qualified clinician before considering any compound discussed below. See Retapedia : Medical disclaimer.

Ipamorelin (also known as Ipamorelin or NNC 26-0161) is a performance-enhancing peptide studied for its effects on growth hormone, sleep, GHS. Selective GHS-R1a agonist pentapeptide raising GH without cortisol or prolactin effects. Phase 2 trial failed; not FDA-approved; limited human data.

Ipamorelin is a synthetic pentapeptide (Aib-His-D-2-Nal-D-Phe-Lys-NH2) selective agonist of the ghrelin/growth hormone secretagogue receptor (GHS-R1a) derived from GHRP-1. Highly selective for GH release without affecting cortisol, prolactin, ACTH, or acetylcholine at any dose (even 200-fold above ED50), distinguishing it from GHRP-2/GHRP-6. Binds to GHSR on pituitary somatotroph cells, activating phospholipase C (PLC) to generate IP3 and DAG, mobilizing intracellular calcium and activating protein kinase C for GH vesicle exocytosis.

Natty status
Ipamorelin is classified as not natty. It is prohibited by WADA and most natural bodybuilding federations. Use places the athlete in the enhanced category. See § Natty status.
Contents [hide]
  1. 1 Overview
  2. 2 Mechanism of action
  3. 3 Reported effects
  4. 4 Dosage and administration
  5. 5 Natty status
  6. 6 Research
  7. 7 Related compounds
  8. 8 References
  9. 9 External links

Overview

Preclinical studies showed dose-dependent increases in GH levels, longitudinal bone growth, and body weight gain in rats, though IGF-1 levels and bone markers remained unchanged.

Phase 2 clinical trials for post-operative ileus failed to show efficacy (no reduction in time to first meal vs placebo).

Limited clinical data on body composition effects in humans despite theoretical benefits.

Typical dosing: 100-300mcg subcutaneously 1-3x daily, preferably on empty stomach.

Best timing: pre-bed (aligns with natural GH surge, improves sleep quality), split dosing (AM fasted + pre-bed) for enhanced pulsatility.

Users report improved sleep quality within 2-4 weeks, with body composition changes over 3-6 months.

Cycling protocol: 8-12 weeks on, with 5-days-on/2-days-off weekly pattern to prevent receptor desensitization.

Minimal side effects: injection site reactions, mild headache, nausea (typically resolve in 1-2 weeks).

Does not suppress endogenous hormone production.

Not FDA-approved; removed from FDA Category 2 compounding list September 2024 due to nominator withdrawal.

FDA recommended against inclusion in 503A Bulks Regulation October 2024 due to insufficient safety data.

No longer available for compounding.

Banned by WADA for competitive sports.

Mechanism of action

Selectively triggers growth hormone release without raising cortisol or prolactin. Human efficacy unproven: a Phase 2 trial failed and body-composition benefits remain preclinical. Subcutaneous injection.

Reported effects

Effects reported in the literature and from preclinical models include:

  • Selectively stimulates growth hormone release via a GHRP-like receptor with potency and efficacy comparable to GHRP-6, without elevating ACTH or cortisol even at doses more than 200-fold above the ED50 for GH release. [1] Preclinical
  • Dose-dependently increases longitudinal bone growth rate and body weight gain in adult female rats after 15 days of subcutaneous administration, without affecting IGF-1 levels or serum bone markers. [2] Preclinical
  • Inhibits cisplatin-induced body weight loss by approximately 24% during the delayed phase (48-72 h) in a ferret model of chemotherapy-associated emesis. [3] Preclinical
  • Suppresses electrically-stimulated ileum contractions in vitro with an IC50 of 11.7 µM, indicating direct gut motility modulation. [3] Preclinical
  • Stimulates spermatogenesis and elevates luteinizing hormone and androgen levels in a fish model, suggesting effects on the hypothalamic-pituitary-gonadal axis. [4] Preclinical
  • Remains an investigational growth hormone axis secretagogue with uncertain efficacy and safety, product quality concerns, and widespread antidoping restrictions, with no reproducible human efficacy evidence for performance or body-composition benefits. [5][6][7] Preclinical

Evidence grades: FDA approved Phase III Phase II Phase I Preclinical Anecdotal

Dosage and administration

⚠
Dosage information is included for encyclopedic purposes only. Retapedia does not provide medical advice. See Retapedia : Medical disclaimer.

Standard dose

  • 100-300mcg per injection, 1-3x daily (subcutaneous)

General

  • Beginners/anti-aging: 200mcg once daily at bedtime
  • Fat loss/general support: 200-300mcg twice daily (AM + pre-bed)
  • Performance/recovery: 300mcg three times daily (AM + post-workout + pre-bed)

Timing

  • On empty stomach, 30-60 min before/after meals

Best time

  • 2 hours before bedtime for sleep and natural GH alignment

Split dosing

  • Space 6-8 hours apart to mimic natural GH pulses

Cycle

  • 8-12 weeks on, with 5-days-on/2-days-off weekly pattern

Results timeline

  • Sleep improvements 2-4 weeks, body composition 3-6 months

Natty status

See also: Peptide § Natty status

Ipamorelin is classified as not natty. It appears on the WADA prohibited list and is banned by major natural bodybuilding federations.[8] Use of this compound places the athlete in the enhanced category rather than the natural category in competitive contexts.

Research

The peptide has been the subject of 9 studies and reference works collected on this site. The full bibliography is in § External links below.

Other peptides in this catalogue with overlapping mechanisms or status:

Epithalon Not natty
Marketed as an anti-aging peptide. In preclinical studies it boosts telomerase activity, supports the body's own melatonin production, and shows antioxidant effects. Human evidence is minimal.
MK-677 Not natty
Oral ghrelin receptor agonist that raises growth hormone and IGF-1. Increases lean mass, bone density, and deep sleep. Causes insulin resistance and elevated blood sugar.
Sermorelin Not natty
Stimulates the pituitary to release growth hormone and IGF-1 under normal feedback control. FDA-approved for GH deficiency; used off-label for anti-aging via nightly injection.
CJC-1295 Not natty
Increases growth hormone and IGF-1 for 6+ days per injection. Improves body composition, muscle recovery, and fat metabolism. Weekly dosing.

References

  1. ^ First selective GHS characterization study
  2. ^ Bone growth in rats research
  3. a b Cisplatin-induced weight loss study
  4. ^ Hypothalamic-pituitary-testicular axis effects
  5. ^ Injectable Peptides in Sports Medicine: A Structured Narrative Review of Evidence, Safety, and Antidoping Implications. Recent review
  6. ^ Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives. Recent review
  7. ^ The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration. Recent review
  8. a b World Anti-Doping Agency. (2026). Prohibited List 2026.

External links

Categories: Peptides | Performance-enhancing substances | Growth hormone | Sleep | GHS | Selective agonist

This page was last updated on July 17, 2026, at 16:22 (UTC).

Research last reviewed on July 17, 2026.

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