Research Comparison
GHRP-6 vs IGF-1 LR3 (Long R3 IGF-1)
A side-by-side research comparison of GHRP-6 and IGF-1 LR3 (Long R3 IGF-1) drawn from Cobalt Peptides' peptide database records.
GHRP-6
GHRP-6 (Growth Hormone Releasing Peptide-6) is a synthetic hexapeptide belonging to the growth hormone secretagogue (GHS) class. It stimulates endogenous growth hormone (GH) release via activation of the ghrelin receptor (GHS-R1a) in the hypothalamus and anterior pituitary. As one of the earliest developed GHRPs, GHRP-6 is well-characterised and widely used in research investigating GH pulsatility, appetite signalling, and metabolic regulation. It is known for its strong orexigenic (appetite-stimulating) effects in addition to GH release.
IGF-1 LR3 (Long R3 IGF-1)
IGF-1 LR3 is a synthetic 83-amino acid analog of insulin-like growth factor-1 (IGF-1), modified with an arginine substitution at position 3 and an extended N-terminal sequence. These modifications significantly reduce binding to IGF-binding proteins (IGFBPs), resulting in prolonged circulation and increased bioavailability. Unlike native IGF-1, which has a short half-life, IGF-1 LR3 exhibits a substantially extended half-life (~20–30 hours), allowing sustained activation of IGF-1 receptors. Despite its potency and widespread research use, it has never been approved for human use and lacks clinical trial data, remaining strictly a research compound.