Comparison
IGF-1 LR3 vs. Tesamorelin
Two peptides side-by-side — identity, evidence base, legal status and known adverse events.
Identity
Category
Growth
Growth
CAS no.
143045-27-6
901758-09-6
Molecular weight
9117.6 g/mol
5135.83 g/mol
Half-life
21 h
0.4 h
Sequence
MFPAMPLSSLFVNGPRTLCGAELVDALQFVCGDRGFYFNKPTGYGSSSRRAPQTGIVDECCFRSCDLRRLEMYCAPLKPAKSAtrans-3-hexenoyl-Tyr-Ala-Asp-Ala-Ile-Phe-Thr-Asn-Ser-Tyr-Arg-Lys-Val-Leu-Gly-Gln-Leu-Ser-Ala-Arg-Lys-Leu-Leu-Gln-Asp-Ile-Met-Ser-Arg-Gln-Gln-Gly-Glu-Ser-Asn-Gln-Glu-Arg-Gly-Ala-Arg-Ala-Arg-Leu-NH2Mechanism of action
IGF-1 LR3
IGF-1 LR3 is a recombinantly produced variant of human IGF-1. Two changes define its properties: (1) at position 3, glutamic acid is replaced by arginine; (2) a 13-amino-acid sequence is added at the N-terminus ('Long'). Both modifications drastically reduce affinity for the six IGF-binding proteins (IGFBP-1 to -6) that normally bind native IGF-1 in the blood and regulate its availability at the receptor. As a result, a larger fraction of the molecule is freely available to bind the type-1 IGF receptor (IGF-1R) — the same receptor as native IGF-1. In preclinical models and cell culture, LR3 IGF-1 therefore acts as a more potent agonist than unmodified IGF-1. The downstream signalling pathway (PI3K/Akt and MAPK) is identical to that of IGF-1; the modification changes bioavailability, not the receptor target.
Tesamorelin
Tesamorelin is an N-terminally modified 44-amino-acid version of human GHRH(1-44). A 3-hexenoyl modification protects against rapid dipeptidyl-peptidase-IV cleavage. Binding to the pituitary GHRH receptor stimulates endogenous pulsatile growth-hormone secretion and consequently hepatic IGF-1 production.
Evidence base
Highest evidence
Animal model
Human RCT
Studies
4
4
of which in humans
0
4
Effects recorded
4
3
Open conflicts
1
1
Documented adverse events
1
2
Legal status
Full entries
Frequently asked questions
- What is the difference between IGF-1 LR3 and Tesamorelin?
- IGF-1 LR3 is classified as "Growth", while Tesamorelin is classified as "Growth". IGF-1 LR3: Synthetic analogue of insulin-like growth factor 1 (IGF-1) carrying an arginine substitution at position 3 and a 13-amino-acid N-terminal extension. These modifications lower binding to IGF-binding proteins and extend its duration of action relative to native IGF-1. LR3 IGF-1 is primarily an established cell-culture reagent (serum-free media, bioprocessing); it is NOT an approved human medicine. Use in the bodybuilding grey market is described; as an IGF-1 analogue, LR3 IGF-1 falls under the WADA anti-doping prohibition. Tesamorelin: Stabilised GHRH analog (growth-hormone-releasing hormone). FDA-approved in 2010 as Egrifta for reduction of abdominal lipohypertrophy in HIV-associated lipodystrophy. Not approved for the general population. This page contrasts both neutrally and source-based — with no usage or dosing recommendation.
- Which peptide is better supported by science, IGF-1 LR3 or Tesamorelin?
- The highest available evidence level is "Animal model" for IGF-1 LR3 and "Human RCT" for Tesamorelin. A higher evidence level means more robust data, but says nothing about suitability for an individual. The full body of evidence is on each peptide's own page.
- What is the legal status of IGF-1 LR3 and Tesamorelin in Germany and the United States?
- Germany: IGF-1 LR3 — Unapproved, Tesamorelin — Unapproved. United States: IGF-1 LR3 — Unapproved, Tesamorelin — Prescription. These are factual summaries with source and review date on the individual pages.