IGF-1 LR3 vs Ipamorelin
A neutral, side-by-side comparison of two performance & growth hormone peptides — their mechanisms, dosing ranges, administration routes, side effects, and research evidence. For research and educational purposes only.
IGF-1 LR3
IGF-1 LR3 (Long Arg3 IGF-1) is a synthetic analogue of Insulin-like Growth Factor 1 with an amino acid substitution at position 3 and a 13-amino acid N-terminal extension. These modifications prevent binding to IGF-binding proteins (IGFBPs), dramatically extending its half-life from ~12 minutes (native IGF-1) to approximately 20–30 hours. IGF-1 LR3 is widely used in research for its ability to promote cellular growth, protein synthesis, hyperplasia, and nutrient uptake into muscle tissue.
Full profileIpamorelin
Ipamorelin is a selective growth hormone secretagogue (GHS) and ghrelin receptor agonist. It stimulates GH release with high selectivity — minimal cortisol or prolactin elevation compared to older GHRPs. Widely used in research protocols for body composition, sleep quality, and recovery.
Full profile| IGF-1 LR3 | Ipamorelin | |
|---|---|---|
| Category | Performance & Growth Hormone | Performance & Growth Hormone |
| Also known as | Insulin-like Growth Factor-1 Long R3, Long R3 IGF-1, Increlex (human equivalent) | NNC 26-0161, Ipamorelin acetate |
| Evidence | Research-stage | Investigational (in trials) |
| Dosing range | 20mcg–100mcg mcg, Once daily post-workout, on training days only (common protocol) | 100mcg–300mcg mcg, 1–3x daily (typically pre-sleep and/or pre-workout) |
| Administration | Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols) | Subcutaneous injection, Intramuscular injection |
| Key side effects | Hypoglycemia (clinically significant — monitor blood sugar carefully), Jaw and organ growth with chronic high-dose use (theoretical at research doses), Fatigue and headaches, Joint pain | Water retention (mild), Tingling / numbness in extremities, Increased appetite, Headache (transient) |
| Cited sources | 3 references | 3 references |
Key differences
- Evidence level differs: IGF-1 LR3 is research-stage, while Ipamorelin is investigational (in trials).
- Administration: IGF-1 LR3 — Subcutaneous injection, Intramuscular injection (into the trained muscle — site-specific protocols); Ipamorelin — Subcutaneous injection, Intramuscular injection.
- Frequency: IGF-1 LR3 is typically Once daily post-workout, on training days only (common protocol); Ipamorelin is 1–3x daily (typically pre-sleep and/or pre-workout).
How each works
IGF-1 LR3
In vitro and animal research establishes IGF-1 LR3 as a potent anabolic and growth-promoting agent. It activates the IGF-1 receptor (IGF-1R) and downstream PI3K/Akt and MAPK/Erk pathways, promoting skeletal muscle hypertrophy and satellite cell activation. Its extended half-life makes it far more active systemically than native IGF-1. Research also documents its role in connective tissue repair, nerve regeneration, and fat oxidation. Human research is limited — most data comes from cancer cell biology and athletic performance settings.
Ipamorelin
Ipamorelin selectively stimulates GH release via the ghrelin receptor (GHS-R1a) without significantly elevating ACTH or cortisol — the feature that distinguishes it from GHRP-6 and GHRP-2 (Raun et al., 1998, in swine/rodent models). Human data are limited: a PK study in 40 volunteers established a ~2-hour half-life (Gobburu et al., 1999), and a Phase 2 trial for postoperative ileus (Beck et al., 2014) failed its primary endpoint. It is not FDA-approved, and claims about body composition or recovery are extrapolated from GH physiology, not human outcome trials.
This comparison aggregates public research and structured profile data for informational purposes only. It is not medical advice and does not recommend either compound for human use. Consult a qualified healthcare provider before considering any peptide.