Ipamorelin

From Retapedia, the free peptide encyclopedia
"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 therapeutically researched peptide studied for its effects on growth hormone, sleep, GHS. Selective GHS-R1a agonist pentapeptide. No cortisol/prolactin effects. Phase 2 trial failed. Not FDA-approved, removed from compounding list 2024. 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 generally regarded as compatible with natural bodybuilding, though competitive federations may differ. 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

Stimulates growth hormone release without cortisol/prolactin effects. Improves sleep quality, recovery, and body composition. Minimal side effects.

Reported effects

Effects reported in the literature and from preclinical models include:

  • Selectively stimulates GH release via the GHRP-receptor (GHS-R1a) with potency 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 [2] Preclinical
  • Inhibits cisplatin-associated body weight loss by approximately 24% during the delayed phase (48–72 h) in a ferret model of chemotherapy-induced emesis [3] Preclinical
  • Suppresses electrically-stimulated ileum contractions in vitro with an IC50 of 11.7 µM, indicating direct gut motility modulation independent of emesis suppression [3] Preclinical
  • Classified as investigational with uncertain safety profile, product quality concerns, and widespread antidoping restrictions by a 2026 structured narrative review of injectable peptides in sports medicine [4][5] 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 generally regarded as compatible with the natty designation, particularly when used for therapeutic healing purposes. Opinions vary across natural bodybuilding federations, and athletes who compete should consult the rulebook of their respective sanctioning body.[6]

Research

The peptide has been the subject of 8 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:

CJC-1295/Ipamorelin Stack Natty
Boosts growth hormone 3-5x higher than individual peptides. Improves sleep quality, muscle mass, fat loss, and recovery. Minimal side effects.
MK-677 Natty
Increases lean muscle mass, bone density, and deep sleep quality. Enhances recovery and tissue healing. Risk of blood sugar issues.
CJC-1295 Natty
Increases growth hormone and IGF-1 for 6+ days per injection. Improves body composition, muscle recovery, and fat metabolism. Weekly dosing.
IGF-1 LR3 Natty
Powerfully increases muscle growth, protein synthesis, and fat burning. Accelerates tissue repair and recovery. Risk of hypoglycemia.

References

  1. ^ First selective GHS characterization study
  2. ^ Bone growth in rats research
  3. a b Cisplatin-induced weight loss study
  4. ^ Injectable Peptides in Sports Medicine: A Structured Narrative Review of Evidence, Safety, and Antidoping Implications. Recent review
  5. ^ Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives. Recent review
  6. a b World Anti-Doping Agency. (2026). Prohibited List 2026.

External links

Categories: Peptides | Therapeutic peptides | Growth hormone | Sleep | GHS | Selective agonist

This page was last edited on May 25, 2026, at 01:15 (UTC).

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