IGF-1 LR3 vs Ipamorelin
Growth Hormone
IGF-1 LR3
83-amino-acid IGF-1 analog engineered for markedly reduced binding to IGF binding proteins.
Growth Hormone
Ipamorelin
Highly selective pentapeptide ghrelin receptor agonist, notable for minimal cross-activation of other pituitary axes.
Side by side
| Dimension | IGF-1 LR3 | Ipamorelin |
|---|---|---|
| Molecular weight A 12.8× difference in mass — these are not comparable on a milligram-for-milligram basis. | 9117.6 g/mol | 711.85 g/mol |
| Size class | protein-scale | short peptide |
| CAS number | 946870-92-4 | 170851-70-4 |
| Research area | growth hormone | growth hormone |
| Sequence | Not published as a linear sequence | Aib-His-D-2-Nal-D-Phe-Lys-NH2 |
| Available sizes | 1mg | 5mg, 10mg |
| Entry price | $69 | $39 |
| Cost per mg Cost per milligram differs by more than 3×. Compare against the concentrations your protocol actually requires, not the headline vial price. | $69.00 | $4.90 |
Mechanism
IGF-1 LR3
IGF-1 LR3 is a recombinant analog of human IGF-1 carrying two modifications: an arginine substitution at position 3, and a 13-amino-acid N-terminal extension. The Arg3 substitution sharply reduces affinity for IGF binding proteins, which normally sequester the great majority of circulating IGF-1. The practical research consequence is a much larger free fraction and correspondingly extended activity — which also means potency comparisons against native IGF-1 are not straightforward.
Ipamorelin
Ipamorelin is a synthetic pentapeptide agonist at the growth hormone secretagogue receptor (GHS-R1a). Its defining research characteristic is selectivity: unlike earlier secretagogues such as GHRP-6 and GHRP-2, it shows minimal effect on ACTH, cortisol, and prolactin at comparable doses in animal models. That clean profile is precisely why it remains a useful tool compound for isolating GH-axis effects.
Evidence quality
Mechanism is not the same as evidence. Where we have assessed the literature, the verdict is stated plainly.
IGF-1 LR3
Evidence base: very thin, sixteen indexed results, dominated by fetal sheep models. The most recent primary result in that model is negative, and a 2025 mouse study shows biomarker change without functional benefit.
Full research reference →Ipamorelin
Evidence base: small but well-defined. The selectivity result is clearly established and the receptor pharmacology is characterised. Primary evidence is concentrated in four papers from 1998 and 1999, with little added since.
Full research reference →Research applications
IGF-1 LR3
- IGF-1 receptor binding and autophosphorylation assays
- IGFBP interaction and displacement studies
- Cell proliferation and differentiation in culture
- Akt/mTOR pathway signaling research
Ipamorelin
- GHS-R1a receptor selectivity and binding studies
- Pituitary somatotroph response assays
- Comparative secretagogue selectivity profiling
- Pulsatile secretion pattern research
Common questions
What is the difference between IGF-1 LR3 and Ipamorelin?
IGF-1 LR3 is 83-amino-acid IGF-1 analog engineered for markedly reduced binding to IGF binding proteins. Ipamorelin is highly selective pentapeptide ghrelin receptor agonist, notable for minimal cross-activation of other pituitary axes. They differ in molecular weight (9117.6 vs 711.85 g/mol) and in the pathways they are studied against.
Which is more cost-effective per milligram, IGF-1 LR3 or Ipamorelin?
Ipamorelin is lower at approximately $4.90 per milligram at its best tier, against $69.00 for the other. Cost per milligram is only meaningful relative to the concentrations a given protocol requires, since these compounds are not used at comparable masses.
Can IGF-1 LR3 and Ipamorelin be studied together?
Combination designs appear in the published literature for a number of these compounds. Whether it is appropriate for a given protocol depends entirely on the model and endpoint. We supply research compounds and do not provide protocol guidance — consult the primary literature for your specific model.
How should IGF-1 LR3 and Ipamorelin be stored?
Store lyophilized at -20°C protected from light. This is a larger protein than most of the catalog and is more sensitive to freeze-thaw; aliquot on first reconstitution. For Ipamorelin: Store lyophilized powder at -20°C protected from light. Reconstituted solution stable at 2-8°C for up to 30 days.
Which has the stronger evidence base?
IGF-1 LR3 — Evidence base: very thin, sixteen indexed results, dominated by fetal sheep models. The most recent primary result in that model is negative, and a 2025 mouse study shows biomarker change without functional benefit. Ipamorelin — Evidence base: small but well-defined. The selectivity result is clearly established and the receptor pharmacology is characterised. Primary evidence is concentrated in four papers from 1998 and 1999, with little added since.
All products sold on this website are intended for research and identification purposes only. These products are not intended for human dosing, injection, or ingestion.
Comparison generated from Lyra Vital catalog data. Every specification is reconciled against the certificate of analysis for the shipped batch.