Ipamorelin

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.

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:

• Released growth hormone from rat pituitary cells and in anaesthetised rats and conscious swine through a GHRP-like receptor, with potency and efficacy similar to GHRP-6. ^[1] Preclinical
• Released growth hormone in swine without raising ACTH or cortisol, even at doses more than 200-fold above the ED50 for growth hormone release. ^[1] Preclinical
• Dose-dependently increased longitudinal bone growth rate and body weight gain in adult female rats over 15 days of subcutaneous dosing, without changing total IGF-I or serum bone turnover markers. ^[2] Preclinical
• Inhibited cisplatin-induced body weight loss by approximately 24 percent during the delayed phase in ferrets, but did not reduce acute or delayed emesis. ^[3] Preclinical
• Inhibited electrically stimulated contractions of isolated ferret ileum by 54.4 percent, with an IC50 of 11.7 micromolar. ^[3] Preclinical
• Increased food intake, spermatocyte and spermatid numbers, serum luteinizing hormone and 11-ketotestosterone in tilapia after 21 days of dosing. ^[4] Preclinical

Evidence grades: FDA approvedApproved (non-US)Phase IIIPhase IIPhase IPreclinicalAnecdotal

Dosage and administration

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

Ipamorelin is classified as not natty. It appears on the WADA prohibited list and is banned by major natural bodybuilding federations.^[5] 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. Additional bibliography is in § External links below.

Related compounds

Other peptides in this catalogue with overlapping mechanisms or status:

References

1. ^ a b 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. ^ a b World Anti-Doping Agency. (2026). Prohibited List 2026.

External links

• Wikipedia article
• Comprehensive GHS review
• Injectable Peptides in Sports Medicine: A Structured Narrative Review of Evidence, Safety, and Antidoping Implications.
• Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives.
• The emerging landscape of performance-enhancing peptides modulating GH-IGF1 axis: bridging the gap between clinical evidence and patient self-administration.
• CJC1295/Ipamorelin — commercial
• 10mg Ipamorelin — commercial
• Bacteriostatic Water Reconstitution Solution 10ml — commercial